P0753

Circuit Description

The 1-2 shift solenoid (1-2 SS) valve controls transmission fluid pressure acting on the 1-2 and 3-4 shift valves to position the valves for the appropriate gear. The 1-2 SS valve is a normally open exhaust valve located on the lower control valve body. Ignition voltage is supplied to the solenoid on circuit 839. The output driver module (ODM), within the PCM, commands the solenoid ON or OFF by providing a ground path through circuit 1222. When the 1-2 SS valve is commanded ON, the PCM senses low voltage. When the 1-2 SS valve is commanded OFF, the PCM senses high voltage.

If the PCM detects voltage limits that do not meet the calibration, then DTC P0753 sets. DTC P0753 is a Type A DTC.

Conditions for Running the DTC

^ No ODM DTC P1650.
^ The engine run time is greater than 5 seconds.

Conditions for Setting the DTC

The PCM detects an open, a short to ground, or a short to power on the 1-2 shift solenoid valve circuits within 5 seconds.

Action Taken When the DTC Sets

^ The PCM illuminates the malfunction indicator lamp (MIL).
^ SERVICE ENGINE SOON, SERVICE TRANSMISSION displays on the driver information center (DIC).
^ The PCM commands 2nd gear.
^ The PCM commands default line pressure.
^ The PCM inhibits TCC engagement.
^ The PCM freezes steady state adapts.
^ The PCM freezes garage shift adapts.
^ The PCM stores DTC P0753 in PCM history.

Conditions for Clearing the MIL/DTC

^ The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ A scan tool clears the DTC from PCM history.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

^ Inspect the wiring at the PCM, the transmission 20-way connector, the 1-2 shift solenoid valve 2-way connector, and all other circuit connecting points for the following conditions:
- A backed out terminal
- A damaged terminal
- Reduced terminal tension
- A chafed wire
- A broken wire inside the insulation
- Moisture intrusion
^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
^ Refer to Shift Solenoid Valve State and Gear Ratio table.

Test Description

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

6. This step verifies that the 1-2 SS valve is operating and that an intermittent condition may have set the DTC.
7. This step isolates the automatic transmission wiring harness so that you can diagnose the engine wiring harness.
9. This step isolates circuit 1222 for an open.
11. This step isolates circuit 1222 of the engine wiring harness for a short to power.
13. This step isolates the engine wiring harness so that you may diagnose the automatic transmission wiring harness.
16. This step measures for a short to ground in circuit 1222.