For 1990-2009 cars

### Circuit Description

The line pressure control (PC) solenoid valve (SLT) regulates solenoid modulator fluid passing through the solenoid into throttle signal pressure. The transmission control module (TCM) uses a pulse width modulated signal in order to control the signal pressure. The TCM compares various inputs in order to determine the appropriate pressure for a given load. The TCM varies the current to the line PC solenoid valve from 0.1 amps, for maximum line pressure to 1.1 amps, for minimum line pressure. An internal current monitor within the TCM provides feedback in order to determine actual line PC solenoid valve current draw.

If the TCM detects a continuous short to voltage in the line PC solenoid valve circuit, then DTC P0963 sets. DTC P0963 is a type A DTC.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0963 Line Pressure Control (PC) Solenoid Control Circuit High Voltage

### Conditions for Running the DTC

• | The engine speed is 400 RPM or greater.

• | The ignition voltage is 10.2-15.5 volts.

• | Trans. protection mode is OFF.

### Conditions for Setting the DTC

The PC solenoid valve feedback circuit indicates a continuous short to voltage for 2 seconds or greater.

### Action Taken When the DTC Sets

• | The TCM requests the powertrain control module (PCM) to illuminate the malfunction indicator lamp (MIL).

• | The TCM requests the PCM to limit engine torque to 150 N·m (111 lb ft).

• | The TCM turns the Trans. Protection Mode ON.

• | The transmission will operate in 5th gear when the transmission is shifted into D range and 2nd gear when shifted into L range.

• | The line pressure is at maximum.

• | The torque converter clutch (TCC) is disabled.

• | The TCM freezes the transmission adaptive functions.

• | The PCM records the operating conditions when the Condition for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.

• | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record.

• | The TCM stores DTC P0963 in TCM history.

### Conditions for Clearing the MIL/DTC

• | The PCM turns off the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.

• | A scan tool can clear the MIL/DTC.

• | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an 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.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step verifies the ability of the TCM to command the line PC solenoid valve.

2. This step verifies that the automatic transmission wiring harness and the line PC solenoid valve have correct resistance.

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 the ignition ON, with the engine OFF.

Important:

• | Before clearing the DTC, use the scan tool in order to record the PCM and the TCM Failure Records. Using the Clear Eng./Trans. DTC Info function erases the Failure Records from the powertrain control module (PCM) and the transmission control module (TCM).

• | Using the Clear Eng./Trans. DTC Info function erases stored DTCs in both the PCM and TCM.

3. Record the DTC Failure Records.
4. Clear the DTC.
5. With a scan tool, select Line PC Solenoid Output Controls.
6. With a scan tool, increase and decrease the line PC solenoid amperage.
7. Observe the scan tool display.

Does the Line pressure control (PC) Sol. Actual Current reading vary from the Line PC Sol. Ref. Current reading by more than the specified amount?

0.10 amp

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3 |

1. Turn OFF the ignition.
2. Disconnect the AT inline 14-way connector. Additional DTCs may set.
3. Using the digital multimeter (DMM) and the J 35616 GM-approved terminal test kit, measure the resistance between low control and high control circuits of the line PC solenoid valve at the transmission side of the AT inline 14-way connector.

Does the resistance measure less than the specified value?

3.8 ohms

Go to Step 4

Go to Step 5

4 | Test the high control circuit of the line PC solenoid valve and the low reference circuit of the line PC solenoid valve for being shorted together between the AT inline 14-way connector and the line PC solenoid valve. Refer to Circuit Testing .

Did you find the condition?

--

Go to Step 8

Go to Step 9

5 | Measure the resistance between the high control circuit of the line PC solenoid valve and all other circuits, except the low control circuit of the line PC solenoid valve at the transmission side of the AT inline 14-way connector. Refer to Testing for Continuity .

Does the resistance measure less than the specified value?

100 ohms

Go to Step 8

Go to Step 6

6 | Test the high control circuit and the low reference circuit of the line PC solenoid valve for a short to voltage or a short together between the AT inline 14-way connector and the TCM. Refer to Testing for Continuity . Did you find the condition? | -- | Go to Step 7 | Go to Step 10
7 | Repair or replace the wiring harness. Refer to Wiring Repairs . Did you complete the replacement? | -- | Go to Step 11 | --
8 | Replace the internal automatic transmission wiring harness assembly (33). Refer to Wiring Repairs . Did you complete the replacement? | -- | Go to Step 11 | --
9 | Replace the control valve body assembly (39). Refer to Control Valve Body Cover Replacement . Is the replacement complete? | -- | Go to Step 11 | --
10 | Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Is the replacement complete? | -- | Go to Step 11 | --
11 | Perform the following procedure in order to verify the repair:

1. Select DTC.
2. Select Clear Info.
3. Operate the vehicle for 12.5 seconds.
4. Select Specific DTC.
5. Enter DTC P0963.

Does the DTC reset?

--

Go to Step 2

Go to Step 12

12 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK