Circuit Description
The pressure control (PC) solenoid valve is an electronic device that regulates transmission line pressure based on the current flow through its coil winding. The magnetic field produced by the coil moves the internal valve of the solenoid, which varies pressure to the pressure regulator valve. The transmission control module (TCM) controls the PC solenoid valve by applying a varying amount of amperage to the solenoid. The applied amperage can vary from 0.1-1.1 amps. Low amperage, 0.1 amp, indicates high line pressure. High amperage, 1.1 amps, indicates low line pressure. The duty cycle of the PC solenoid valve is expressed as a percentage of energized ON time. 0 percent indicates 0 ON time, non-energized, or no current flow. Approximately 60 percent at idle indicates maximum ON time, energized, or high current flow. The TCM determines the appropriate line pressure for a given load by comparing the throttle position sensor voltage, the engine speed and other inputs.
When the TCM detects a continuous open or short to ground in the PC solenoid valve circuit, then DTC P0961 sets. DTC P0961 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0961 Line Pressure Control (PC) Solenoid System Performance
Conditions for Running the DTC
| • | The system voltage is 8-18 volts. |
| • | The engine is running for 5 seconds or greater. |
Conditions for Setting the DTC
DTC P0961 sets when the duty cycle is outside the range of 0.5-95 percent for 2 seconds or greater.
Action Taken When the DTC Sets
| • | The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL). |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM records this information as a Failure Record. |
| • | The TCM commands maximum line pressure. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM stores DTC P0961 in TCM history. |
Conditions for Clearing the DTC
| • | A scan tool can clear the DTC. |
| • | The TCM clears the DTC from 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 switch is OFF long enough in order to power down the TCM. |
Diagnostic Aids
DTC P0961 may set under low voltage conditions caused by high electrical system demands.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that the fault is present.
-
This step tests the transmission wiring harness and the PC solenoid valve for correct resistance.
-
This step begins diagnosis of the engine side of the circuit.
Step | Action | Value | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. Using the Clear Info function will erase the stored Failure Records from the TCM. Does the PC Sol. Actual Current reading vary from the PC Sol. Ref. Current reading by more than the specified amount? | 0.16 amp | Go to Step 3 | Go to Testing for Intermittent Conditions and Poor Connections | |
Refer to Automatic Transmission Inline 20-Way Connector End View . Does the resistance measure within the specified range? | 3-7 ohms | Go to Step 7 | Go to Step 4 | |
4 | Is the resistance greater than the specified value? | 7 ohms | Go to Step 5 | Go to Step 6 |
5 |
Did you find the condition? | -- | Go to Step 15 | Go to Step 14 |
6 | Test the high control circuit and the low control circuit of the PC solenoid valve for a short together between the AT inline 20-way connector and the PC solenoid valve. Refer to Circuit Testing . Did you find the condition? | -- | Go to Step 15 | Go to Step 14 |
7 |
Refer to Automatic Transmission Inline 20-Way Connector End View and Circuit Testing . Did you find the condition? | -- | Go to Step 15 | Go to Step 8 |
8 |
Refer to Automatic Transmission Inline 20-Way Connector End View and Circuit Testing . Did you find the condition? | -- | Go to Step 15 | Go to Step 9 |
Does the resistance measure within the specified range? | 3-7 ohms | Go to Step 13 | Go to Step 10 | |
10 | Does the resistance measure greater than the specified value? | 7 ohms | Go to Step 11 | Go to Step 12 |
11 |
Did you find and correct the condition? | -- | Go to Step 17 | -- |
12 | Test the high control circuit and the low control circuit of the PC solenoid valve for a short together between the TCM and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | -- |
13 |
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 |
14 | Replace the pressure control solenoid valve. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
15 | Replace the automatic transmission wiring harness assembly. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- |
16 | Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 17 | -- |
17 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 18 | Go to Step 2 |
18 | With a scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |
