TG91 - Check For Intermittent Fault In Harness and Connectors

Diagnostic Trouble Codes (DTC) 99/624 and 651 indicate an Electronic Pressure Control (EPC) circuit failure.

DTCs 67/634 indicate the Manual Lever Position (MLP) sensor voltage is higher or lower than expected.

Possible causes:
- Damaged harness connector.
- Damaged EPC solenoid.
- Damaged MLP sensor.
- Intermittent harness continuity.
- Damaged Powertrain Control Module (PCM) connector pins.

- Key "OFF".

- Disconnect PCM. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.

- Install breakout box, connect PCM.

- Connect Digital Volt/Ohm Meter (DVOM) to test pins as indicated:

- For EPC solenoid: Connect one test lead to EPC signal pin and the other to EPC VPWR pin. Refer to schematics for correct EPC test pin. TG - Testing Schematic

- For MLP sensor: Connect one test lead to MLP signal pin and the other test lead to test pin 46. Refer to schematics for correct MLP test pin. TG - Testing Schematic

- Key "ON", engine "OFF".

- Observe DVOM display for indication of a fault while performing the following:

NOTE: In either case the voltage should remain steady (less than 10.0 volts for the EPC and less than 5.0 volts for the MLP with vehicle in PARK). A changing voltage or one greater than expected is an indication of a fault.

- Shake, wiggle and bend the component harness. Lightly tap on the component connector to simulate a road shock.

- Is a fault indicated?

Yes -- Isolate fault and service as necessary. Clear continuous memory. Clearing Diagnostic Trouble Codes

Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)

If the concern still exists, refer to Transmission and Drivetrain for possible internal transmission damage.

No -- Go to Transmission and Drivetrain. Clear continuous memory. Clearing Diagnostic Trouble Codes