Circuit Description
The PCM turns on the bulb, LED, or driver info center indicator by supplying a path to ground through the PCM.
Conditions for Setting the DTC
| • | Ignition is on. |
| • | An improper voltage level has been detected on the alternator lamp driver circuit. |
| • | Above conditions for at least 20 seconds. |
Action Taken When the DTC Sets
| • | The PCM will not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data. |
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear Info function. |
Diagnostic Aids
A PCM controlled lamp on at all times most likely indicates that a condition is present which requires the attention of the vehicle operator. Conditions which will illuminate each lamp are as follows:
| • | When the engine speed is greater than 1200 RPM and system voltage falls below 10 volts for longer than 10 seconds. The PCM commands the generator ON when system voltage rises to above 12 volts. |
| • | When the generator control circuit remains low for longer than 10 seconds. |
| • | When the engine speed is below 2000 RPM and the generator PWM control circuit duty cycle remains low for longer than 20 seconds. |
| • | When the engine speed is above 4000 RPM and the generator PWM control circuit duty cycle remains high for longer than 20 seconds. |
For diagnosis of the instrument panel, perform the System Check in the Instrument Cluster section of Electrical Diagnosis.
Check for the following conditions:
| • | Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the PCM and turn the ignition on. Observe a voltmeter connected to the affected PCM output circuit while moving connectors and wiring harnesses related to the PCM output circuit. A change in voltage will indicate the location of the fault. |
| • | Engine Oil Level Sensor circuit: If the problem was with the Low Oil Level lamp and Chart did not isolate a problem, use Engine Oil Level Sensor Diagnosis. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart.
-
Normally, ignition feed voltage should be present on the output driver circuit with the PCM disconnected and the ignition turned on.
-
Checks for a shorted component or a short to battery positive voltage on the output driver circuit. Either condition would result in a measured current of over 1.5 amps. Also checks for a component that is going open while being operated, resulting in a measured current of 0.0 amps.
-
Checks for a faulty instrument cluster.
-
This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On Board Diagnostic (OBD) System Check performed? | -- | ||
2 | Was the instrument cluster system check in Electrical Diagnosis performed? | -- | Go to Electrical Diagnosis | |
Is voltage near the specified value? | B+ | |||
Does the current reading remain between the specified values? | 0.05 Amp 1.5 Amps | |||
Is voltage at the specified value? | 0.0 V | |||
6 | Locate and repair short to voltage in affected PCM output circuit. Refer to Repair Procedures in Electrical Diagnosis. Is the action complete? | -- | -- | |
7 | Check the ignition feed fuse for the instrument panel cluster indicator lamps. Is the fuse blown? | -- | ||
8 |
Is the action complete? | -- | -- | |
9 |
Is voltage near the specified value? | B+ | ||
10 |
Was a problem found? | -- | ||
11 |
Was a problem found? | -- | ||
12 |
Does the test light flash on and off? | -- | Refer to Diagnostic Aids | |
13 |
Was a problem found? | -- | ||
14 | Locate and repair open in ignition feed circuit to the instrument panel cluster indicator lamps. Refer to Repair Procedures in Electrical Diagnosis. Is the action complete? | -- | -- | |
15 | Replace the instrument panel cluster. Is the action complete? | -- | -- | |
Replace the PCM. Important: : Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming Is the action complete? | -- | -- | ||
17 |
Note test result, does scan tool indicate DTC P1663 failed this ignition? | -- | Repair complete |
