GM Service Manual Online
For 1990-2009 cars only

DTC P1864 Non-Europe or N. American Emissions

Circuit Description

The pressure control valves 3, 4, 5, and 6 are precision electronic pressure regulators that control the operation of the clutches, brakes and lock-up clutch.

The valve reduces the system pressure with which the downstream solenoid valves and electrical pressure regulating valves are supplied. It is possible to use smaller solenoid valves as a result. The pressure control valves require a constant input pressure.

Conditions for Setting the DTC

    • Output voltage of the solenoid valve 5 is less than 2 volts.
    • No DTC P1865, P1866.
    • Immediately after the above condition occurs.

Action Taken When the DTC Sets

    • The hold lamp will blink.
    • The transmission control module (TCM) will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.
    • Adopt Emergency/Substitute mode and constant 4th gear by hydraulic control.
    • After ignition OFF/ON: 3rd gear by hydraulic control. P, R and N also possible.
    • Power supply cut off to the pressure control solenoid valve.

Conditions for Clearing the Hold Lamp/DTC

    • The hold lamp will turn OFF when the malfunction has not occurred after 3 ignition cycles.
    • A history DTC will clear after 40 consecutive warm-up cycles without a fault.
    • Using a scan tool can clear history DTCs.

Diagnostic Aids

When DTC P1864 sets, the possible cause of fault could be the pressure control valve 5.

DTC P1864

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Select "Actuating" on the scan tool.
  4. Actuate pressure control valve 5 ON/OFF.

Does the valve change ON/OFF?

--

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn the ignition OFF.
  2. Disconnect the transaxle wiring connector.
  3. Measure the resistance between terminals 5 and 10 of the transaxle wiring connector.

Is the resistance within the specified value?

TFT 25°C (77°F)

6 ohms

Go to Step 7

Go to Step 4

4

  1. Remove the oil pan.
  2. Disconnect the wiring connector of pressure control solenoid valve 5.
  3. Measure the resistance between terminal 2 of the solenoid valve 5 and ground.
  4. Measure the resistance between terminal 1 of the solenoid valve 5 and ground.

Is the resistance within the specified value?

Go to Step 6

Go to Step 5

5

Repair the internal line for valve 5 for a short to ground.

Is the repair complete?

--

System OK

--

6

Replace solenoid valve 5.

Is the replacement complete?

--

System OK

--

7

  1. Disconnect the transaxle wiring connector and TCM connector.
  2. Measure the resistance between terminal 5 of the transaxle wiring connector and ground.
  3. Measure the resistance between terminal 10 of the transaxle wiring connector and ground.

Is the resistance within the specified value?

Go to Step 9

Go to Step 8

8

Repair the transaxle wiring harness for a short to ground.

Is the repair complete?

--

System OK

--

9

Replace the TCM. Refer to Transmission Control Module Replacement .

Is the replacement complete?

--

Go to Step 10

--

10

  1. After the repair, use a scan tool "clear info" function and road tests the vehicle.
  2. Review the "DTC info".

Has the last test failed or is the current DTC displayed?

--

Go to Step 2

System OK

DTC P1864 European and N. Amercan Emissions

Circuit Description

The pressure control valves 3, 4, 5, and 6 are precision electronic pressure regulators that control the operation of the clutches, brakes, and lock-up clutch.

The valve reduces the system pressure with which the downstream solenoid valves and electrical pressure regulating valves are supplied. It is possible to use smaller solenoid valves as a result. The pressure control valves require a constant input pressure.

Conditions for Setting the DTC

    • Output voltage of the solenoid valve 5 is less than 2 volts.
    • No DTC P1865, P1866.
    • Immediately after the above condition occurs

Action Taken When the DTC Sets

    • The malfunction indicator lamp (MIL) will illuminate.
    • The transmission control module (TCM) will record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records buffer.
    • Adopt Emergency/Substitute mode and constant 4th gear by hydraulic control.
    • After ignition OFF/ON: 3rd gear by hydraulic control. P, R, and N also possible.
    • Power supply cut off to the pressure control solenoid valve.

Conditions for Clearing the MIL/DTC

    • The MIL will turn OFF when the malfunction has not occurred after 3 ignition cycles.
    • A history DTC will clear after 40 consecutive warm-up cycles without a fault.
    • Using a scan tool can clear history DTCs.

Diagnostic Aids

When DTC P1864 sets, the possible cause of fault could be the pressure control valve 5.

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Select Actuating on the scan tool.
  4. Actuate pressure control valve 5 ON/OFF.

Does the valve change ON/OFF?

--

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn the ignition OFF.
  2. Disconnect the transaxle wiring connector.
  3. Measure the resistance between terminals 5 and 10 of the transaxle wiring connector.

Is the resistance within the specified value?

TFT 25°C (77°F)

6 ohms

Go to Step 7

Go to Step 4

4

  1. Remove the oil pan.
  2. Disconnect the wiring connector of pressure control solenoid valve 5.
  3. Measure the resistance between terminal 2 of the solenoid valve 5 and ground.
  4. Measure the resistance between terminal 1 of the solenoid valve 5 and ground.

Is the resistance within the specified value?

Go to Step 6

Go to Step 5

5

Repair the internal line for valve 5 for a short to ground.

Is the repair complete?

--

System OK

--

6

Replace solenoid valve 5.

Is the replacement complete?

--

System OK

--

7

  1. Disconnect the transaxle wiring connector and transmission control module (TCM) connector.
  2. Measure the resistance between terminal 5 of the transaxle wiring connector and ground.
  3. Measure the resistance between terminal 10 of the transaxle wiring connector and ground.

Is the resistance within the specified value?

Go to Step 9

Go to Step 8

8

Repair the transaxle wiring harness for a short to ground.

Is the repair complete?

--

System OK

--

9

Replace the TCM. Refer to Transmission Control Module Replacement .

Is the replacement complete?

--

Go to Step 10

--

10

  1. After the repair, use a scan tool Clear Info function and road tests the vehicle.
  2. Review the DTC Info.

Has the last test failed or is the current DTC displayed?

--

Go to Step 2

System OK