With Powertrain Control Module

Wiring Diagram:

CIRCUIT DESCRIPTION

The Pressure Control Solenoid Valve (PC Sol. Valve) is a Powertrain Control Module (PCM) controlled device that regulates the transmission line pressure. The PCM compares the Accelerator Pedal Position (APP) Sensor voltage, engine RPM, and other inputs in order to determine the appropriate line pressure for a given load. The PCM regulates the pressure by applying a varying amperage to the PC Sol. Valve. The applied amperage varies from 0.1 amps for maximum line pressure to 1.1 amps for minimum line pressure. The PCM monitors the circuit amperage.

If the PCM detects a PC duty cycle that exceeds 95% or is less than 1.9%, then DTC P0748 sets. DTC P0748 is a type D DTC.


CONDITIONS FOR SETTING THE DTC

^ The system voltage is 9.0-16.0 volts.

^ The engine must be running greater than 475 RPM for at least 7 seconds.

^ The PC duty cycle exceeds 95% or is less than 1.9%.

^ All conditions met for 200 milliseconds (0.2 seconds).

ACTION TAKEN WHEN THE DTC SETS

^ The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

^ The PCM disables the PC Sol. Valve, defaulting the transmission to maximum line pressure.

^ The PCM freezes shift adapts.

^ DTC P0748 is stored in PCM history.


CONDTIONS FOR CLEARING THE DTC

^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS

^ Inspect the wiring at the PCM, the transmission connector and all other circuit connecting points for the following conditions:

- A bent terminal

- A backed out terminal

- A damaged terminal

- Poor terminal tension

- A chafed wire

- A broken wire inside the insulation

- Moisture intrusion

- Corrosion

^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.

^ Inspect for any transmission DTCs that may have reset.

TEST DESCRIPTION

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

2. This step tests the ability of the PCM to command the PC Sol. Valve.

3. This step tests the PC Sol. Valve and the Automatic Transmission Wiring Harness Assembly for incorrect resistance.

6. This step tests the PC sol. valve and the internal wiring harness for a short to ground.

8. When performing this step refer to Product Service Bulletin #9474L80E-07 for PC Sol. Valve Application.

9. This step tests the entire PC sol. valve circuit for proper resistance.

10. This step tests for a short to ground in circuits 1228 and 1229 of the engine harness.