GM Service Manual Online
For 1990-2009 cars only

DTC P1810, P1815, or P1816 V6

DTC Descriptor

The diagnostic procedure supports the following DTCs:

    • DTC P1810 Transmission Fluid Pressure (TFP) Position Switch Circuit
    • DTC P1815 Transmission Fluid Pressure (TFP) Valve Position Switch - Start in Wrong Range
    • DTC P1816 Transmission Fluid Pressure (TFP) Valve Position Switch Indicates Park/Neutral (P/N) with Drive Ratio

Circuit Description

The automatic transmission fluid pressure (TFP) manual valve position switch consists of five pressure switches (two normally-closed and three normally-open) and a transmission fluid temperature (TFT) sensor combined into one unit. The combined unit mounts on the valve body. The transmission control module (TCM) supplies ignition voltage for each range signal. By grounding one or more of these circuits through various combinations of the pressure switches, the TCM detects which manual valve position you select. The TCM compares the actual voltage combination of the switches to a TFP manual valve position switch combination chart stored in memory.

The TFP manual valve position switch cannot distinguish between park and neutral because the monitored valve body pressures are identical. With the engine off and the ignition switch on, the TFP manual valve position switch indicates park/neutral. Disconnecting connector X121 - X1 from the transmission removes the ground potential for the three range signals to the TCM. In this case, with the engine off, and the ignition switch on, D2 will be indicated.

When the TCM detects an invalid state of the TFP manual valve position switch circuit by deciphering the TFP manual valve position switch inputs, then either DTC P1810, P1815 or P1816 sets. All these DTCs are a type B DTC.

Refer to Automatic Transmission Controls Schematics , Automatic Transmission Inline 20-Way Connector End View, Automatic Transmission Internal Connector End Views , Automatic Transmission Control Module Connector End Views , and Automatic Transmission Related Connector End Views to aid in diagnosis.

Conditions for Running the DTC

P1810

    • The system voltage is 8-18 V.
    • The engine speed is greater than 500 RPM for 5 seconds.

P1815

    • No DTCs P0722 or P0723
    • The system voltage is 8-18 V.
    • The engine speed is less than 50 RPM, then 50-650 RPM for 0.75 seconds, then greater than 650 RPM for 5 seconds.
    • Output shaft speed less than 250 RPM

P1816

    • No DTCs P0722 or P0723
    • The system voltage is 8-18 V.
    • The engine speed is less than 50 RPM, then 50-650RPM for 0.75 seconds, then greater than 650 RPM for 5 seconds.
    • Output shaft speed less than 250 RPM

Conditions for Setting the DTC

P1810

DTC 1810 sets when the TCM detects an invalid TFP manual valve position switch state for 60 seconds.

P1815

DTC 1815 sets when the TCM detects D2 only, TFP manual valve position switch state after engine start for 7 seconds.

P1816

DTC 1816 sets when the TCM detects one of the following conditions for 13 seconds.

    • Park/neutral indicated with a 1st gear ratio
    • Park/neutral indicated with a 2nd gear ratio
    • Park/neutral indicated with a 3rd gear ratio
    • Park/neutral indicated with a 4th gear ratio

Action Taken When the DTC Sets

    • The TCM requests the ECM to illuminate the check powertrain icon during the second consecutive trip in which the conditions for setting the DTC are met.
    • The TCM commands maximum line pressure.
    • The TCM freeze transmission adaptive functions.
    • The TCM inhibits TCC engagement.
    • The TCM commands 4th gear.
    • At the time of the first failure, the TCM records the opening conditions when the conditions for setting the DTC are met. The TCM stores this information as a Failure Record.
    • At the time of the second failure, the ECM records the operating conditions when the conditions for setting the DTC are met. The ECM stores this information as a Freeze Frame.
    • The TCM stores the DTC in TCM history during the second consecutive trip in which the conditions for setting the DTC are met.

Conditions for Clearing the DTC

    • The ECM turns off the check powertrain icon after the fourth consecutive drive trip in which the TCM does not send a check powertrain icon illumination request.
    • Tech 2 can clear the DTC.
    • The TCM clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
    • The TCM cancels the DTC default actions when the ignition is off long enough in order to power down the TCM.

Diagnostic Aids

    • Refer to Transmission Fluid Pressure Manual Valve Position Switch Logic for the normal range signals and the invalid combinations. On the table, LOW is 0 V, HI is ignition voltage.
    • Sediment in the valve body may cause improper operation of the TFP manual valve position switch. If the presence of sediment is suspected, clean the valve body and replace the TFP manual valve position switch.

Test Description

The following numbers refer to the step numbers in the diagnostic table:

3 Checks indicated range signal to the selected manual valve position.

4-5 Checks for correct voltage from the TCM to the transmission inline 20-way connector.

6 Checks if there is a short between any of the signal circuits.

Step

Action

Yes

No

1

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to Diagnostic System Check - Automatic Transmission

2

Inspect for correct transmission fluid level, refer to Transmission Fluid Check.

Did you perform the fluid checking procedure?

Go to Step 3

Refer to Transmission Fluid Check

3

  1. Connect Tech 2 to the DLC.
  2. Turn on the Ignition, with the engine off.
  3. Important: Before clearing the DTC, use the Tech 2 Freeze Frame/Failure Record in order to record the transmission parameters at the time the DTC set. Using Tech 2 to clear the DTCs erases the Freeze Frame/Failure Record records from the TCM.

  4. On Tech 2 select:
  5. Transmission / Automatic Transmission / Diagnostic Trouble Codes / Freeze Frame.

  6. Select the relevant DTC and note the parameters at the time of the DTC setting.
  7. On Tech 2 select:
  8. Diagnostic Trouble Codes / Clear Engine and Transmission DTCs.

  9. Follow the instructions on Tech 2 and clear the DTCs.
  10. Start the engine and idle at normal operating temperature.
  11. Apply the brake pedal.
  12. On Tech 2 select:
  13. Data Display / Transmission Data.

  14. Select each selected transmission range: P, R, N, D4, D3, D2 and D1.

Does each selected transmission range match the TFP Gear displayed on Tech 2?

Check for an intermittent fault in the circuit , refer to Testing for Intermittent Conditions and Poor Connections

Go to Step 4

4

  1. Turn off the ignition.
  2. Disconnect connector X121 - X1 from the transmission.
  3. Important: Additional DTCs may set

  4. To turn on the ignition, with the engine off.

Does Tech 2 display Open 12 V for any of the TFP Switch. A/B/C parameters?

Go to Step 5

Go to Step 7

5

  1. Turn off the ignition.
  2. Install Tool No. J 44152 Jumper Harness (20 pins) on the harness connector X121 - X1.
  3. Turn the ignition, with the engine off.
  4. Using a multimeter set to measure voltage, probe between the following pins and ground:
  5. • Connector X121 - X1 pin P
    • Connector X121 - X1 pin R
    • Connector X121 - X1 pin N

Did the multimeter display 10-12 V for all the tests?

Go to Step 6

Go to Step 8

6

  1. Disconnect connector A112 - X1 from the TCM.
  2. Using a multimeter set to measure resistance, probe across the following pins:
  3. • Connector X121 - X1 pins P and R
    • Connector X121 - X1 pins P and N
    • Connector X121 - X1 pins R and N

Does the multimeter display continuity in any of the tests?

Go to Step 9

Go to Step 10

7

Test the circuit (A/B/C) that displayed Closed on Tech 2, for a short to ground between connector X121 - X1 and A112 - X1.

Did you find and correct the condition?

Go to Step 12

Go to Step 11

8

Test the signal circuits of the TFP manual valve position switch that did not indicate battery voltage for an open circuit between connectors X121 - X1 and A112 - X1.

Did you find and correct the condition?

Go to Step 12

Go to Step 11

9

Test the affected signals circuits of the TFP manual valve position switch for a shorted together condition between connectors X121 - X1 and A112 - X1.

Did you find and correct the condition?

Go to Step 12

Go to Step 11

10

Test the TFP circuits for an open circuit or shorted condition between connector X121 - X1.

Did you find a condition?

Replace the control valve body wiring harness, refer to Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness

Go to Step 12

Replace the TFP manual valve position switch, refer to Transmission Fluid Pressure Manual Valve Position Switch Logic

Go to Step 12

11

Replace the TCM refer Transmission Control Module Replacement.

Did you complete the replacement.

Go to Step 12

--

12

Perform the following procedure in order to verify the repair:

  1. On Tech 2 select:
  2. Diagnostic Trouble Codes / Clear Engine and Transmission DTCs.

  3. Follow the instructions on Tech 2 and clear any DTCs.
  4. Operate the vehicle under the following conditions:
  5. • Turn on the ignition, with the engine off for at least 2 seconds.
    • Start the vehicle and idle for 5 seconds.
    • Drive in D4 until the TCC locks for 10 seconds.
    • Continue to run the engine for at least 60 seconds from startup.
  6. On Tech 2 select:
  7. Diagnostic Trouble Codes / Read DTC Information.

Has DTC P1810 set?

Go to Step 2

Go to Step 13

13

On Tech 2 select:

Diagnostic Trouble Codes / Read DTC Information.

Does Tech 2 display any DTCs you have not diagnosed?

Refer to Scan Tool Data List

System OK

When all diagnosis and repairs are completed, check the system for correct operation.