GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Vivant 🢒 Transmission/Transaxle 🢒 Automatic Transmission - ZF 4HP 16 🢒 DTC P1861

Circuit Description

The pressure control solenoid (PCS) valves 3, 4, 5, and 6, are precision electronic pressure regulators that control the operation of the clutches, the brakes, and the 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 PCS requires a constant input pressure.

Conditions for Setting the DTC
    • The output voltage of the PCS 4 is less than 2 volts.
    • No DTCs P1862 or P1863 are set.

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 the ignition is OFF/ON: 3rd gear by hydraulic control. Possible P, R, and N are also possible.
    • The power supply is cut off to the PCS 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 P1861 sets, the possible cause of the fault could be the PCS 4 valve.

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check - Automatic Transmission?

--

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2
  1. Install the scan tool.
  2. Turn the ignition ON, with the engine OFF.
  3. Select Actuating on the scan tool.
  4. Actuate pressure control solenoid (PCS) 4 ON/OFF.

Does the PCS 4 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 7 of the transaxle wiring connector.

Is the resistance within the specified values?

6 ohms

Go to Step 7

Go to Step 4

4
  1. Remove the oil pan.
  2. Disconnect the wiring connector of PCS 4.
  3. Measure the resistance between terminal 2 of PCS 4 and ground.
  4. Measure the resistance between terminal 1 of PCS 4 and ground.

Is the resistance within the specified value?

∞ ohms

Go to Step 6

Go to Step 5

5

Repair the internal line, PCS 4, for a short to ground.

Did you complete the repair?

--

System OK

--

6

Replace the PCS 4.

Did you complete the replacement?

--

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 7 of the transaxle wiring connector and ground.

Is the resistance within the specified value?

∞ ohms

Go to Step 9

Go to Step 8

8

Repair the transaxle wiring harness for a short to ground.

Did you complete the repair?

--

System OK

--

9

Replace the TCM. Refer to Transmission Control Module Replacement .

Did you complete the replacement?

--

Go to Step 10

--

10
  1. Clear the DTCs with a scan tool.
  2. Road test the vehicle.
  3. Observe the DTC information with a scan tool.

Are there any DTCs displayed that have not been diagnosed?

--

Go to Step 2

System OK