Circuit Description
The pressure control (PC) solenoid valve is located in the valve body. The PC solenoid valve controls transmission line pressure based on current flow through its windings. The transmission control module (TCM) determines desired line pressure based on throttle position and other inputs. The TCM then varies the duty cycle on the high side of the PC solenoid valve to control current flow to the solenoid. Current is controlled from about 0.02 amps for maximum line pressure to 1.1 amps for minimum line pressure. The TCM monitors the actual current to the solenoid.
If the TCM detects a commanded current draw that differs from the actual current draw by more than a calibrated value, 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 PC solenoid valve is enabled.
Conditions for Setting the DTC
DTC P0961 sets when the duty cycle is outside the range of 0.5-95 percent for 0.2 seconds.
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 commands maximum line pressure. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records. |
| • | The TCM stores DTC P0961 in TCM history. |
Conditions for Clearing the DTC
| • | The TCM clears the DIC message when the condition no longer exits. |
| • | A scan tool can clear the DIC/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 fault no longer exists and the DTC passes. |
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(s) | 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 |
Refer to Testing for Continuity . 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: Did you find the condition? | -- | Go to Step 15 | Go to Step 8 |
8 |
Refer to: 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 |
Refer to Testing for Continuity and Wiring Repairs . 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 |
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 |
14 | Replace the pressure control solenoid valve. Refer to Control Valve Upper Body Disassemble in the 4T80-E section of the Transmission Unit Repair Manual. Did you complete the replacement? | -- | Go to Step 17 | -- |
15 | Replace the automatic transmission wiring harness assembly. Refer to Input Speed Sensor and Wiring Harness Removal in the 4T80-E section of the Transmission Unit Repair Manual. Did you complete the replacement? | -- | Go to Step 17 | -- |
16 | Replace the TCM. Refer to Control Module References . 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 |
