P0748

DIAGNOSTIC TROUBLE CODE (DTC) P0748 PRESSURE CONTROL SOLENOID (PCS) CIRCUIT ELECTRICAL





Circuit Description
The Pressure Control Solenoid Valve (PC Sol. Valve) is used to regulate transmission line pressure. The PC Sol. Valve consists of an electrical connector, coil, armature, regulating spring and a poppet valve. The PC Sol. Valve is attached to the upper control body. The PCM compares TP voltage, engine rpm and other inputs to determine the line pressure appropriate for a given load.
The PCM will regulate pressure by applying a varying amperage to the PC Sol. Valve. The applied amperage can vary from 0.1 to 1.0 amps. The PCM then monitors the amperage at the return line.
When the PCM detects a continuous open or short to ground in PC Sol. Valve circuit or the PC Solenoid Valve, then DTC P0748 sets.

Conditions For Setting The DTC
- System voltage is 9-16 volts.

Action Taken When The DTC Is Set
- Freeze shift adapts from being updated.
- PCM commands maximum line pressure (0 Amps).
- DTC P0748 will be stored in PCM memory.
- PCM will NOT illuminate the Malfunction Indicator Lamp (MIL).

Conditions For Clearing The DTC
- System voltage is 10-17 volts.
- History DTCs can be cleared by using a Scan Tool.

Diagnostic Aids
- Inspect the wiring for poor electrical connections at the PCM and at the transmission 20-way connector.
- Look for possible bent, backed out, deformed or damaged terminals. Check for weak terminal tension as well. Also check for chafed wires that could short to bare metal or other wiring. Inspect for broken wire inside the insulation.
- If diagnosing for a possible intermittent short or open condition, move or massage the wiring harness while observing test equipment for a change.
- Extended engine cranking with a low battery could set DTC P0748.

Test Description
The numbers below refer to the step numbers on the diagnostic chart.
2. This test checks the ability of the PCM to command the PC Sol. Valve.
3. This test checks internal transmission wiring and the PC Sol. Valve for correct resistance.
8. This test checks circuit 505 of the transmission wiring for a short to ground.
9. This test checks circuit 505 from the engine 20-way connector for a short to ground.
10. This test checks circuit 505 from the engine 20-way connector to the PCM for an open.
11. This test checks circuit 504 from the engine 20-way connector to the PCM for a short to ground.
12. This test checks circuit 504 from the engine 20-way connector to the PCM for an open.





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DTC P0748 - Pressure Control Solenoid Circuit Electrical





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