INSTRUMENTAL PANEL CLUSTER (TACHOMETER DIAGNOSTIC)
VEHICLES AFFECTED: 1988-90 OLDSMOBILE CUTLASS SUPREME
THIS BULLETIN CANCELS AND DELETES BULLETIN REF.#938137.
Tachometer diagnostic information given in Section 8A-81 of the 1988, 1989 and 1990 Oldsmobile Cutlass Supreme Chassis Service Manuals is incorrect. Please mark or reference to this bulletin the following pages in your copies of the 1988, 1989 and 1990 Oldsmobile Cutlass Supreme Chassis Service Manuals.
Model Year Old Page New Page ----------- --------- -------- 1988 8A-81-0 8A-81-0 1988 8A-81-1 8A-81-1 1988 8A-81-8 8A-81-8 1988 8A-81-9 8A-81-9 1988 8A-81-10 8A-81-10 1988 8A-81-10A 1988 8A-81-15 8A-81-15 1988 8A-81-16 8A-81-16
1989 8A-81-0 8A-81-0 1989 8A-81-1 8A-81-1 1989 8A-81-7 8A-81-7 1989 8A-81-8 8A-81-8 1989 8A-81-9 8A-81-9 1989 8A-81-9A 1989 8A-81-14 8A-81-14 1989 8A-81-15 8A-81-15
1990 8A-81-0 8A-81-0 1990 8A-81-1 8A-81-1 1990 8A-81-7 8A-81-7 1990 8A-81-8 8A-81-8 1990 8A-81-9 8A-81-9 1990 8A-81-9A 1990 8A-81-15 8A-81-15
ELECTRONIC INSTRUMENT CLUSTER: GAGES (UB3)
With the Ignition Switch in RUN, Blue-Green PRND21 appears, Check Mechanical and Lights on, move the Gear and Gear selected will shift linkage Selector into each position appear highlighted in from "P" through "1" bright orange
Turn on the Park Lights The Vacuum Fluorescent See Interior Displays and Cluster Lights Dimming illumination are dimmed (Section 8A-117) to the present Dimmer Control Setting
Adjust the Dimmer Control in The Cluster brightness See Interior both directions varies with the dimmer Lights Dimming setting (Section 8A-117)
Turn on the headlights to Hi The Hi Beam Indicator Do Test A: Beam, then to off lights when the hi beams Connector Pin- are on OutTest
With Ignition in RUN, operate The Turn Indicators flash See Exterior the turn signals in both with the Turn Signal lights (Section directions lights 8A-110)(Also see Test A terminals C2 and C3)
Turn on the Hazard Switch Both Turn Indicators flash See Exterior simultaneously. lights (Section 8A-110)
With Ignition in RUN, engage The Brake Indicator See Brake Warn- the Parking Brake lights ing System (Section 8A-41) (Also see Test A terminal C4)
Start the engine Tachometer displays See System engine RPM Oil Pressure Diagnosis Gage displays the oil pressure Voltmeter displays charging system voltage
NOTE: If speed signal is detected during the start up sequence, the start up sequence is stopped and the gages will immediately indicate the correct values.
If all results are normal, the system is OK.
SYSTEM DIAGNOSIS
For Instrument Cluster removal and replacement procedures, see Section 8C of the Service Manual.
If a bidirectional Scan tool is available, refer to the Trouble Code Section on page 8A-81-17 for Scan tool diagnosis.
Do the tools listed for your symptom in the Symptom Table below, or when directed by the System Check.
Tests follow the Symptom Table.
ELECTRONIC INSTRUMENT CLUSTER: GAGES (UB3)
SYMPTOM TABLE
Symptom For Diagnosis ------- ------------- Panel -----
Illumination lights do not light Do Test A (check Terminals C11 and D1)
Display elements do not light at all See Test A (check Terminal C12, C14, C16 and D14 and D16)
Display segments are not all lit or the Replace the Instrument Cluster digits displayed are incomplete (see Section 8C)
Cluster
Illumination brightness does not vary Do Test A(Check Terminal C11) with Dimmer Switch
Digital display brightness does not vary Do Test A(check Terminal C10 and with the Dimmer Switch, or when lights are D10) turned on
Digital displays do not change between Replace the Instrument Cluster English and Metric (see Section 8C)
Display Elements light up constantly or Replace the Instrument Cluster when they should be off (see Section 8C)
Speedometer/Odometer --------------------
Speedometer does not operate. Odometers Replace the Instrument Cluster are OK (see Section 8C)
One or both Odometers do not operate. Do Test N Speedometers are OK
Speedometer and Odometer(s) do not Replace the Instrument Cluster operate. (see Section 8C)
Trip Odometer resets when the Ignition See Test A (Check Terminal D16) is switched off
Speedometer and Odometers are not Do Test O accurate
The Digital Speedometer and Graph Replace the Instrument Cluster Speedometer values differ (see Section 8C)
Tachometer
Tachometer does not operate at all Check for IPC codes using a bi- directional scan tool. Check for poor Instrument Cluster terminal contact and for an open or short to ground on the ORN (461) wire. If OK, replace the Instrument Cluster (See Section 8C).
The Tachometer readings are incorrect Replace the Instrument Cluster (see Section 8C)
FUEL
Fuel Gage always indicates a Full Tank Do Test B (also see Test A, terminal D13) Fuel Gage always indicates an Empty Tank Do Test C (also see Test A, terminal D13) Fuel Gage reading is incoffect Do Test D (also see Test A, terminal D13) Fuel Low Indicator does not flash when Replace the Instrument Cluster only one fuel segment is lit (see Section 8C)
Fuel Low Indicator does not light when Replace the Instrument Cluster only three fuel segments are lit (see Section 8C)
Fuel Low Indicator lights when more than Replace the Instrument Cluster three fuel segments are lit (see Section 8C)
VOLTS
Display does not light at all, other Replace the Instrument Cluster displays are OK (see Section 8C)
Display reading is incorrect Replace the Instniment Cluster (see Section 8C) OIL
Display reads low pressure at all times Do Test E (Also see Test A terminal D11) Display reads maximum pressure constantly Do Test F (Also see Test A terminal D11) Display reading is incorrect Do Test G (Also see Test A terminal D11) TEMP
Display never shows any temperature with Do Test H (Also see Test A engine running terminal D12)
Bar Graph shows maximum temperature with Do Test I (Also see Test A engine cold terminal D12)
Display reading is incorrect Do Test J (Also see Test A terminal D12) HOT Indicator does not flash when 13 or Replace the Instrument more bars are lit Cluster (see Section 8C)
HOT Indicator flashes when Gage reads Replace the Instrument normally Cluster (see Section 8C)
INDICATORS
BRAKE Indicator does not operate properly Refer to Brake Warning System (Section 8A-41) SERVICE ENG. SOON Indicator does not Refer to Section 6E of the operate properly Service Manual
FASTEN BELTS Indicator does not light Refer to Wamings and Alarms (Section 8A-76) CHARGE Indicator does not operate properly Refer to Starter and Charging System (Section 8A-30)
Right or Left Turn Indicators do not light Refer to Exterior Lights (Section 8A-110) Hi Beam Indicator does not light Refer to Headlights (Section 8A-100) SHIFT Indicator does not operate properly Do Test K
LOW COOLANT Indicator does not light with Do Test L coolant level low (V6 only)
LOW COOLANT Indicator is lit with coolant Do Test M level OK (V6 only)
N: SPEEDOMETER/ODOMETER TEST
1. Check to see if Cruise Control is working.
If the Cruise Control is working, check to DK GRN wire from S217 to the Instrument Cluster connector terminal D15 for an open or short. Replace the cluster if the wire is OK.
If the Cruise is not working, go to Step 2.
2. Raise the Vehicle so that the drive wheels may be turned by hand. While measuring voltage at the Instrument Cluster Connector Terminal D15 using ground as reference, put the Ignition Switch in RUN, the gear selector in Neutral and turn the drive wheels.
If the voltage varies between 4 and less than 1 volt replace the Instrument Cluster (see Section 8C).
If the voltage is not varying, check the DK GRN (389), PPL (401), and YEL (400) wires for an open or short to ground. Check the Vehicle Speed Sensor (refer to 8A-33). If all are OK, replace the ECM.
O: SPEEDOMETER ACCURACY TEST
(J-33431-10 connector lead available)
Disconnect Connector C100 and connect the J-33431-10 cable to I/P tester J-33431 and to terminal H4 and ground. With the tester set to "ON", "54 mph" and "60 Hz" and the Ignition Switch in RUN, the Speedometer should read 54 mph +/- 2 mph.
If the Speedometer reads correctly, replace the Electronic Control Module (ECM).
If the Speedometer does not read correctly, replace the Instrument Cluster (see Section 8C).
CIRCUIT OPERATION
The operation of an individual indicator is described along with its circuit. Refer to the schematic and text for the circuit that is referenced below each indicator.
FUEL DISPLAY
The Fuel Gage Sender provides a signal to the Instrument Cluster that is related to the fuel level. With a full tank the Fuel Gage Sender resistance is 88 ohms, and with an empty; tank the resistance is less than 1 ohm. The Instrument Cluster electronics converts the analog signal from the Fuel Gage Sender to a digital signal which controls the vacuum fluorescent Fuel Gage Display. When 3 or fewer bars are lit the word LOW is illuminated. With only 1 bar lit, the word LOW flashes on and off.
TEMPERATURE DISPLAY
The Coolant Temperature Sender provides a signal to the Instrument Cluster that is related to the engine's temperature. With the engine at 100 DEG F the sender resistance is 1320 ohms and only one bar is lit. When the engine reaches a temperature of 280 DEG F all 16 bars will light. Beginning with the illumination of the thirteenth bar the word HOT will begin flashing. The Tem- perature Gage Display receives its signals through the Instrument Cluster, which is connected to the Coolant Temperature Sender.
OIL PRESSURE DISPLAY
The Oil Pressure Sender provides a signal to the Cluster that is related to the Oil Pressure. At 81 PSI all 16 bars are lit and the sender has a resistance of 84 ohms. At 7 PSI the first or second bars are illuminated and the word LOW is flashing. Above 16 PSI the word LOW turns off. The Oil Pressure Display receives its signals through the Instrument Cluster which is directly connected to the Oil Pressure Sender.
VOLTS DISPLAY
The Instrument Cluster receives battery voltage from the incoming power leads. The Instrument Cluster's internal circuitry converts the analog voltage to digital voltage where it is displayed by the Volts Gage. At 10 volts the first bar is illuminated. For every half volt above 10 volts one additional bar is illuminated until the sixteenth bar is illuminated at 17.5 volts.
TACHOMETER DISPLAY
The Tachometer is an analog display with a range from 0 to 7000 rpm. The redline is engine dependent. The display consists of 71 bars. Bars 2 thru 6 are activated simultaneously for speeds from 0 to 500 rpm. From the 7th to the 31st bar (3000 rpm), each bar is independently controlled and represents 100 rpm increments. Beyond the 31st bar the bars are tied together in pairs. Each pair represents 200 rpm.
The Tachometer data is supplied to the cluster on the Serial Data Line.
PRNDL DISPLAY
The PRNDL Display consists of indicators, Park R, N, D, 2, 1. Gear selection is shown by the illumination of a rectangular box around the appropriate letter. The PRND21 select is mechanical.
SPEEDOMETER and ODOMETER DISPLAYS
The Odometer and Trip Odometer are digital displays. The Trip Odometer memory is maintained with the ignition "OFF". Its maximum display is 999.9 miles (1609.3 Km/h) and will automatically reset when this limit is reached. The Trip Odometer can be manually reset only with the Odometer in the "trip" mode. The Odometer maximum display is 621,503 miles (999,999 Km). The Odometer retains its memory even when the battery is disconnected.
The Speedometer consists of both an analog and a digital display. The analog display consists of 91 bars. The bars light in pairs. Each pair of bars represents 2 MPH (4Km/h). The segments above 85 MPH (138 Km/h) will not light except during the initialization sequence. The digital display shows the vehicle speed in increments of 1 MPH (1 Km/h). The digital display will show actual vehicle speed.
The Odometers and the Speedometer receive vehicle speed information from the Vehicle Speed Sensor through the ECM and the 389 circuit.
SERVICE ENGINE SOON INDICATOR
The SERVICE ENG. SOON Indicator serves as a warning light to tell the driver that a problem has occurred ane the car should be serviced.
It is also used by the technician to help read out diagnostic codes to help diagnose system problems.
The Indicator receives battery voltage in RUN, BULB TEST and START. The ECM provides a switched path to ground.
LOW COOLANT INDICATOR
The LOW COOLANT Indicator comes on to warn the driver when a low level of coolant exists in the radiator. Battery voltage is applied in RUN, BULB TEST and START. The ECM provides a switched path to ground.
TRIP/SEASON SWITCH ------------------ The Trip/Season Switch is used to change between the Trip Odometer and Season Odometer display.
Depressing the Trip/Season Switch (with Season Odometer displayed) will display the Trip Odometer. Depressing the Resets Switch (after the Trip Odometer is displayed) resets the Trip Odometer to zero. Depressing the Trip/Season Switch again (with the Trip Odometer displayed) returns the Display to the Season Odometer.
ENGLISH/METRIC SWITCH --------------------- The Speedometer, Odometer, Oil Pressure Display and Temperature Display can be either English or Metric. When the English/Metric Switch is depressed the English/Metric input to the cluster is grounded. This ground input to the cluster will enable the cluster to change to the Metric code.
ELECTRONIC INSTRUMENT CLUSTER: GAGES (UB3)
With the Ignition Switch in Blue-Green PRN D21 appears, Check RUN, and Lights on, move the and Gear selected Mechanical Gear Selector into each will appear shift linkage position from "P" through highlighted in bright orange "1" Turn on the Park Lights The Vacuum Fluorescent Dis- See Interior plays and Cluster illumina- Lights Dimming tion are dimmed to the present (Section 8A-117) Dimmer Control Setting (Also see Test A terminals D10 and C10)
Adjust the Dimmer Control in The Cluster brightness varies See Interior both directions with the dimmer setting Lights Dimming (Section 8A-117) (Also see Test A terminals D10)
Turn on the headlights to Hi The Hi Beam indicator lights Do Test A: Beam, then to off when the hi beams are on Connector Pin- Out Test(check terminal C7)
With Ignition in RUN, operate The Turn Indicators flash with See Exterior the turn signals in both the Turn Signal lights lights (Section directions 8A-110)(Also see Test A terminals C2 and C3) Turn on the Hazard Switch Both Turn Indicators flash See Exterior simultaneously lights (Section 8A-110)
With Ignition in RUN, engage The Brake Indicator lights See Brake Warn- the Parking Brake ing System (Section 8A-41) (Also see Test A terminal C4)
Start the engine Tachometer displays engine RPM See System Diagnosis Oil Pressure Gage displays the See System oil pressure Diagnosis Voltmeter displays charging Replace the system voltage Instrument Cluster (see Section 8C)
NOTE: If speed signal is detected during the start up sequence, the start up sequence is stopped and the gages will immediately indicate the correct values.
If all results are normal, the system is OK.
System Diagnosis
For instrument cluster removal and replacement procedures, see Section 8C of the Service Manual
If a bidirectional Scan tool is available, refer to the Trouble Code Section on Page 8A-81-21 for Scan tool diagnosis.
Do the tests listed for your symptom in the Symptom Table below, or when directed by the System Check.
Tests follow the Symptom Table.
SYMPTOM TABLE
SYMPTOM FOR DIAGNOSIS -------- -------------- Panel ----- Illumination lights do not light Do Test A (check Terminals C11 and D1) Display elements do not light at all See Test A (check Terminals C14, C16 and D16) Display gages or the digits are Replace the Instrument incomplete Cluster (see Section 8C)
CLUSTER
Illumination brightness does not vary with Park or Headlights on and Dimmer Switch adjusted.
Speedometer, Odometer and Driver Information Do Test N System speed and distance do not change between English and metric values when the Instrument Cluster English/metric switch is pressed
Driver Information System speed and distance Do Test N do not change between English and metric values when the Instrument Cluster English /metric switch is pressed
Heater and A/C Control Assembly (C68 only) Check the LT BLU (811) wire temperatures do not change between DEG F for an open. If OK, replace and DEG C when the Instrument Cluster the Heater and A/C Control English/metric switch is pressed Assembly
Speedometer and Odometer speed and distances Replace the Instrument do not change between English and metric values Cluster (see Section 8C) when the Instrument Cluster English/metric switch is pressed but the Driver Information System or Heater and A/C Control Assembly (C68 only) values do change
Display display brightness does not vary with Do Test A (check Terminals the Dimmer Switch, or when lights are turned on C10 and D10)
Display Elements light up constantly or when Replace the Instrument they should be off Cluster (see Section 8C)
SPEEDOMETER/ODOMETER
Speedometer does not operate. Odometers are OK Replace the Istrument Cluster (see Section 8C) One or both Odometers do not operate. Replace the Instrument Speedometers are OK Cluster (see Section 8C)
Speedometer and Odometer(s) do not operate Refer to Vehicle Speed Sensor (Section 8A-33) Trip Odometer resets when the Ignition is See Test A(check Terminal switched off D16)
Speedometer and Odometers are not accurate Refer to Vehicle Speed Sensor (Section 8A-33) The Digital Speedometer and Graph Speedometer Replace the Instrument values differ Cluster (see Section 8C)
TACHOMETER
Tachometer does not operate properly Check for IPC codes using a bi-directional scan tool. If IPC codes are set, clear codes and check Tachometer operation Check for poor Cluster Connector terminal contact and for an open or short to ground on the ORN(461) wire. If OK,replace the Instrument Cluster (see Section 8C). FUEL ---- Fuel Gage always indicates a Full Tank Do Test B (also see Test A, terminal D13) Fuel Gage always indicates an Empty Tank Do Test C (also see Test A, terminal D13) Fuel Gage reading is incorrect Do Test D (also see Test A, terminal D13) Fuel Low Indicator does not flash when Replace the Instrument all fuel segments are off Cluster (see Section 8C) Fuel Low Indicator does not turn on when Replace the Instrument only two fuel segments are lit Cluster (see Section 8C) Fuel Low Indicator lights when more than Replace the Instrument two fuel segments are lit Cluster (see Section 8C)
VOLTS
Display does not light at all, other Replace the Instrument displays are OK Cluster (see Section 8C)
Display reading is incorrect Replace the Instrument Cluster (see Section 8C) OIL --- Display reads low pressure at all times Do Test E (Also see Test A terminal D11) Display reads maximum pressure constantly Do Test F (Also see Test A terminal D11) Display reading is incorrect Do Test G (Also see Test A terminal D11) TEMP ---- Display never shows any temperature with Do Test H (Also see Test A engine running terminal D12)
Bar Graph shows maximum temperature with Do Test I (Also see Test A engine cold terminal D12)
Display reading is incorrect Do Test J (Also see Test A terminal D12)
HOT Indicator does not flash when 13 or Replace the Instrument more bars are lit Cluster (see Section 8C)
HOT Indicator flashes when Gage reads normally Replace the Instrument Cluster (see Section 8C)
INDICATORS
BRAKE Indicator does not operate properly Refer to Brake Warning System (Section 8A-41) SERVICE ENG. SOON Indicator does not Refer to Section 6E of operate properly the Service Manual
FASTEN BELTS Indicator does not light Refer to Warnings and Alarms (Section 8A-76) CHARGE indicator does not operate properly Refer to Starter and Charging System (Section 8A-30) Right or Left Turn Indicators do not light Refer to Exterior Lights (Section 8A-110) Hi Beam Indicator does not light Refer to Headlights (Section 8A-100) SHIFT Indicator does not operate properly Do Test K
LOW COOLANT Indicator does not light with Do Test L coolant level low (V6 only)
LOW COOLANT Indicator is lit with coolant Do Test M level OK (V6 only)
ELECTRONIC INSTRUMENT CLUSTER: GAGES
If the speed and distance values are in metric, check the LT BLU (811) wire, Driver Information System and Heater and A/C control head (C68 only) for a short to ground. Replace/repair as necessary.
2. With the Ignition switch in RUN, connect a fused jumper between the instrument cluster connector terminal C9 and ground. Observe the Driver Information System.
If the speed and distance values are displayed in metric, replace the Instrument Cluster.
If the fuse in the jumper blows, check the LT BLU (811) wire, Driver Information System and Heater and A/C Control Head (C68 only) for a short to battery. Replace/ repair as necessary.
If the speed and distance values are not displayed in metric check the LT BLU (811) wire for an open. Check the Driver Information System and Heater and A/C Control Head (C68 only) for a short to battery. Replace/repair as necessary.
CIRCUIT OPERATION
The operation of an individual indicator is described along with its circuit. Refer to the schematic and text for the circuit that is referenced below each indicator.
FUEL DISPLAY
The Fuel Gage Sender provides a signal to the Instrument Cluster that is related to the fuel level. With a full tank the Fuel Gage Sender resistance is 88 ohms, and with an empty tank the resistance is less than 18 ohms. The Instrument Cluster electronics converts the analog signal from the Fuel Gage Sender to a digital signal which controls the vacuum fluorescent Fuel Gage Display. When 3 or fewer bars are lit the word LOW is illuminated. With only 1 bar lit, the word LOW flashes on and off.
TEMPERATURE DISPLAY
The Coolant Temperature Sender provides a signal to the Instrument Cluster that is related to the engine's temperature. With the engine at 100 DEG F the sender resistance is 1320 ohms and only one bar is lit. When the engine reaches a temperature of 280 DEG F all 16 bars will light. Beginning with the illumination of the thirteenth bar the word HOT will begin flashing. The Tem- perature Gage Display receives its signals through the Instrument Cluster, which is connected to the Coolant Temperature Sender.
OIL PRESSURE DISPLAY
The Oil Pressure Sender provides a signal to the Cluster that is related to the Oil Pressure. At 81 PSI all 16 bars are lit and the sender has a resistance of 84 ohms. At 7 PSI the first or second bars are illuminated and the word LOW turns off. The Oil Pressure Display receives its signals through the Instrument Cluster which is directly connected to the Oil Pressure Sender.
VOLTS DISPLAY
The Instrument Cluster receives battery voltage from the incoming power leads. The Instrument Cluster's internal circuitry converts the analog voltage to digital voltage where it is displayed by the Volts Gage. At 10 volts the first bar is illuminated. For every half volt above 10 volts one additional bar is illuminated until the sixteenth bar is illuminated at 17.5 volts.
TACHOMETER DISPLAY
The Tachometer is an analog display with a range from 0 to 7000 rpm. The redline is engine dependent. The display consists of 71 bars. Bars 2 thru 6 are activated simultaneously for speeds from 0 to 500 rpm. From the 7th to the 31st bar (3000 rpm), each bar is independently controlled and represents 100 rpm increments. Beyond the 31st bar the bars are tied together in pairs. Each pair represents 200 rpm.
The Tachometer data is supplied to the cluster on the Serial Data Line.
PRNDL DISPLAY
The PRNDL Display consists of 7 indicators, Park, R, N, D, 2, 1. Gear selection is shown by the illumination of a rectangular box around the appropriate letter. The PRN DL21 select is mechanically operated.
SPEEDOMETER and ODOMETER DISPLAYS
The Odometer and Trip Odometer are digital displays. The Trip Odometer memory is maintained with the ignition "OFF". Its maximum display is 999.9 miles (1609.3 Km/h) and will automatically reset when this limit is reached. The Trip Odometer can be manually reset only with the Odometer in the "trip" mode. The Odometer maximum display is 621,503 miles (999,999 Km). The Odometer retains its memory even when the battery is disconnected.
The Speedometer consists of both an analog and a digital display. The analog display consists of 91 bars. The bars light in pairs. Each pair of bars represents 2 MPH (4Km/h). The segments above 85 MPH (138 Km/h) will not light except during the initialization sequence.
The digital display shows the vehicle speed in increments of 1 MPH (1 Km/h). The digital display will show actual vehicle speed.
The Odometers and the Speedometer receive vehicle speed information from the Vehicle Speed Sensor through the ECM and the 389 circuit.
SERVICE ENGINE SOON INDICATOR
The SERVICE ENG. SOON Indicator serves as a warning light to tell the driver that a problem has occurred and the car should be serviced. It is also used by the technician to help read out diagnostic codes to help diagnose system problems.
The Indicator receives battery voltage in RUN, BULB TEST and START. The ECM provides a switched path to ground.
LOW COOLANT INDICATOR
The LOW COOLANT Indicator comes on to warn the driver when a low level of coolant exists in the radiator. Battery voltage is applied in RUN, BULB TEST and START. The ECM provides a switched path to ground.
TRIP/SEASON SWITCH ------------------ The Trip/Season Switch is used to change between the Trip Odometer and Season Odometer display.
Depressing the Trip/Season Switch (with Season Odometer displayed) will display the Trip Odometer. Depressing the Reset Switch (after the Trip Odometer is displayed) resets the Trip Odometer to zero. Depressing the Trip/Season Switch again (with the Trip Odometer displayed) returns the Display to the Season Odometer.
ENGLISH/METRIC SWITCH --------------------- The English/metric switch located on the instrument Cluster allows the driver to have speed and distance information displayed English or Metric values. This English/metric switch also has an output to the Driver Information System (DIS) and Heater and A/C Control Assembly (C68 only). With the Instrument Cluster English/metric switch in metric, this output is grounded. With this switch in English the output is pulled up to 5 volts by the Instrument Cluster. The DIS also has an English/metric switch, but it has no effect on the Instrument Cluster or the Heater and A/C Control Assembly displays.
ELECTRONIC INSTRUMENT CLUSTER: GAGES (UB3)
With the Ignition Switch in Blue-Green PRN D21 appears, Check RUN, and Lights on, move the and Gear selected Mechanical Gear Selector into each will appear shift linkage position from "P" through highlighted in bright orange "1" Turn on the Park Lights The Vacuum Fluorescent Dis- See Interior plays and Cluster illumina- Lights Dimming tion are dimmed to the present (Section 8A-117) Dimmer Control Setting (Also see Test A terminals D10 and C10)
Adjust the Dimmer Control in The Cluster brightness varies See Interior both directions with the dimmer setting Lights Dimming (Section 8A-117) (Also see Test A terminals D10)
Turn on the headlights to Hi The Hi Beam indicator lights Do Test A: Beam, then to off when the hi beams are on Connector Pin- Out Test(check terminal C7)
With Ignition in RUN, operate The Turn Indicators flash with See Exterior the turn signals in both the Turn Signal lights lights (Section directions 8A-110)(Also see Test A terminals C2 and C3) Turn on the Hazard Switch Both Turn Indicators flash See Exterior simultaneously lights (Section 8A-110)
With Ignition in RUN, engage The Brake Indicator lights See Brake Warn- the Parking Brake ing System (Section 8A-41) (Also see Test A terminal C4)
Start the engine Tachometer displays engine RPM See System Diagnosis Oil Pressure Gage displays the See System oil pressure Diagnosis Voltmeter displays charging Replace the system voltage Instrument Cluster (see Section 8C)
NOTE: If speed signal is detected during the start up sequence, the start up sequence is stopped and the gages will immediately indicate the correct values.
If all results are normal, the system is OK.
System Diagnosis
For instrument cluster removal and replacement procedures, see Section 8C of the Service Manual
If a bidirectional Scan tool is available, refer to the Trouble Code Section on Page 8A-81-21 for Scan tool diagnosis.
Do the tests listed for your symptom in the Symptom Table below, or when directed by the System Check.
Tests follow the Symptom Table.
SYMPTOM TABLE SYMPTOM FOR DIAGNOSIS ------- ------------- PANEL ----- Illumination lights do not light Do Test A (check Terminals C11 and D1) Display elements do not light at all See Test A (check Terminals C14, C16 and D16) Display gages or the digits are incomplete Replace the Instrument Cluster (see Section 8C) CLUSTER
Illumination brightness does not vary with Do Test A(check Terminal C11) Park or Headlights on and Dimmer Switch adjusted
Speedometer, Odometer and Driver Information Do Test N System speed and distance do not change between English and metric values when the Instrument Cluster English/metric switch is pressed
Driver Information System speed and distance Do Test N do not change between English and metric values when the Instrument Cluster English/metric switch is pressed
Heater and A/C Control Assembly (C68 only) Check the LT BLU (811) wire temperature does not change between DEG F for an open. If OK, replace and DEG C when the Instrument Cluster E/M the Heater and A/C Control switch is pressed Assembly
Speedometer and Odometer speed and distances Replace the Instrument do not change between English and metric Cluster (see Section 8C) values when the Instrument Cluster E/M switch is pressed, but the Driver Information System or Heater and A/C Control Assembly (C68 only) values do change
Display display brightness does not vary with Do Test A (check Terminals the Dimmer Switch, or when lights are turned C10 and D10) on
Display Elements light up constantly or when Replace the Instrument they should be off Cluster (see Section 8C)
SPEEDOMETER/ODOMETER
Speedometer does not operate. Odometers are OK Replace the Instrument Cluster (see Section 8C)
One or both Odometers do not operate. Replace the Instrument Speedometers are OK Cluster (see Section 8C)
Speedometer and Odometer(s) do not operate Refer to Vehicle Speed Sensor (Section 8A-33) Trip Odometer resets when the ignition is See Test A (check switched off Terminal D16)
Speedometer and Odometers are not accurate Refer to Vehicle Speed Sensor (Section 8A-33)
The Digital Speedometer and Graph Replace the Instrument Speedometer values differ Cluster (see Section 8C)
TACHOMETER ---------- Check for IPC codes using a bi-directional scan tool. Tachometer does not operate properly If IPC codes are set, clear codes and check Tachometer operation Check for poor Cluster Connector terminal contact and for an open or short to ground on the ORN (461) wire. If OK, replace the Instrument Cluster(see Section 8C).
FUEL
Fuel Gage always indicates a Full Tank Do Test B (also see Test A, terminal D13) Fuel Gage always indicates an Empty Tank Do Test C (also see Test A, terminal D13) Fuel Gage reading is incorrect Do Test D (also see Test A, terminal D13) Fuel Low Indicator does not flash when Replace the Instrument all fuel segments are off Cluster (see Section 8C)
Fuel Low Indicator does not turn on when Replace the Instrument only two fuel segments are lit Cluster (see Section 8C)
Fuel Low Indicator lights when more Replace the Instrument than two fuel segments are lit Cluster (see Section 8C)
VOLTS
Display does not light at all, other Replace the Instrument displays are OK Cluster (see Section 8C) Display reading is incorrect Replace the Instrument Cluster (see Section 8C)
Display reads low pressure at all times Do Test E (Also see Test A terminal D11) Display reads maximum pressure constantly Do Test F (Also see Test A terminal D11) Display reading is incorrect Do Test G (Also see Test A terminal D11) TEMP
Display never shows any temperature with Do Test H (Also see Test A engine running terminal D12)
Bar Graph shows maximum temperature with Do Test I (Also see Test A engine cold terminal D12)
Display reading is incorrect Do Test J (Also see Test A terminal D12) HOT Indicator does not flash when 13 or more Replace the Insturment bars are lit Cluster (see Section 8C)
HOT Indicator nashes when Gage reads normally Replace the Instrument Cluster (see Section 8 INDICATORS ---------- BRAKE Indicator does not operate properly Refer to Brake Waming System (Section 8A-41) SERVICE ENG. SOON Indicator does not operate Do Test 0 properly
FASTEN BELTS Indicator does not light Refer to Wamings and Alarms (Section 8A-76) CHARGE Indicator does not operate properly Refer to Starter and Charging System (Section 8A-30) Right or Left Tum Indicators do not light Refer to Exterior Lights (Section 8A-110) Hi Beam Indicator does not light Refer to Headlights (Section 8A-100) SHIFT Indicator does not operate properly Do Test K
LOW COOLANT Indicator does not light with Do Test L coolant level low
LOW COOLANT Indicator is lit with coolant Do Test M level OK
VOLTS DISPLAY
The Instrument Cluster receives battery voltage from the incoming power leads. The Instrument Cluster's internal circuitry converts the analog voltage to digital voltage where it is displayed by the Volts Gage. At 10 volts the first bar is illuminated. For every half volt above 10 volts one additional bar is illuminated until the sixteenth bar is illuminated at 17.5 volts.
TACHOMETER DISPLAY
The Tachometer is an analog display with a range from 0 to 7000 rpm. The redline is engine dependent. The display consists of 71 bars. Bars 2 thru 6 are activated simultaneously for speeds from 0 to 5 00 rpm. From the 7th to the 31st bar (3000 rpm), each bar is independently controlled and represents 100 rpm increments. Beyond the 31st bar the bars are tied together in pairs. Each pair represents 200 rpm.
The Tachometer data is supplied to the cluster on the Serial Data Line.
PRNDL DISPLAY
The PRNDL Display consists of 7 indicators, Park, R, N, D, 2, 1. Gear selection is shown by the illumination of a rectangular box around the appropriate letter. The PRN(D)DL21 select is mechanically operated.
SPEEDOMETER and ODOMETER DISPLAYS
The Odometer and Trip Odometer are digital displays. The Trip Odometer memory is maintained with the ignition "OFF". Its maximum display is 999.9 miles (1609.3 Km/h) and will automatically reset when this limit is reached. The Trip Odometer can be manually reset only with the Odometer in the "trip" mode. The Odometer maximum display is 621,503 miles (999,999 Km). The Odometer retains its memory even when the battery is disconnected.
The Speedometer consists of both an analog and a digital display. The analog display consists of 91 bars. The bars light in pairs. Each pair of bars represents 2 MPH (4Km/h). The segments above 85 MPH (138 Km/h) will not light except during the initialization sequence. The digital display shows the vehicle speed in increments of 1 MPH (I Km/h). The digital display will show actual vehicle speed.
The Odometers and the Speedometer receive vehicle speed information from the Vehicle Speed Sensor through the ECM and the 389 circuit.
SERVICE ENGINE SOON INDICATOR
The SERVICE ENG. SOON Indicator serves as a warning light to tell the driver that a problem has occurred and the car should be serviced. It is also used by the technician to help read out diagnostic codes to help diagnose system problems.
The Indicator receives battery voltage in RUN, BULB TEST and START. The ECM provides a switched path to ground.
LOW COOLANT INDICATOR
The LOW COOLANT Indicator comes on to warn the driver when a low level of coolant exists in the radiator. Battery voltage is applied in RUN, BULB TEST and START. The ECM provides a switched path to ground.
TRIP/SEASON SWITCH ------------------ The Trip/Season Switch is used to change between the Trip Odometer and Season Odometer display.
Depressing the Trip/Season Switch (with Season Odometer displayed) will display the Trip Odometer. Depressing the Reset Switch (after the Trip Odometer is displayed) resets the Trip Odometer to zero. Depressing the Trip/ Season Switch again (with the Trip Odometer displayed) returns the Display to the Season Odometer.
ENGLISH/METRIC SWITCH --------------------- The English/metric switch located on the Instrument Cluster allows the driver to have speed and distance information displayed English or Metric values. This English/metric switch also has an output to the Driver Information System (DIS) and Heater and A/C Control Assembly (C68 only). With the Instrument Cluster English/metric switch in metric, this output is grounded. With this switch in English the output is pulled up to 5 volts by the Instrument Cluster. The DIS also has an English/metric switch, but it has no effect on the Instrument Cluster or the Heater and A/C Control Assembly displays.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
