For 1990-2009 cars

Perform this test before a hoist or road test in order to make sure that electronic control inputs are connected and operating. If you do not check the inputs before operating the transmission, you could misdiagnose a simple electrical condition as a major transmission condition.

A scan tool provides valuable information. Use a scan tool for accurate diagnosis.

1. Move the gear selector to PARK and set the parking brake.
2. Connect the scan tool to the DLC terminal.
3. Start the engine.
4. Connect power to the scan tool.
5. Verify that the following signals are present on the scan tool:

• | ENGINE SPEED

• | TRANS ISS

• | TRANS OSS

• | VEHICLE SPEED

• | TFP Switch A/B/C

• | PC ACT. Current

• | PC REF. Current

• | PC DUTY CYCLE

• | BRAKE SWITCH

• | ECT

• | TRANS FLUID TEMP

• | TP ANGLE

• | IGNITION VOLTAGE

6. Monitor the BRAKE SWITCH signal while tapping the brake pedal with your foot:

• | BRAKE SWITCH should be Open when the pedal is depressed.

• | BRAKE SWITCH should be Closed when the pedal is released.

7. Monitor the PRNDL SELECT signal and move the gear selector through all of the ranges:

• | Verify that the PRNDL SELECT value matches the gear range indicated on the instrument panel or the console.

• | Gear selections should be immediate and not harsh.

8. Move the gear selector to NEUTRAL and monitor the TP ANGLE signal while increasing and decreasing the engine RPM with the accelerator pedal. TP ANGLE should increase with the engine RPM.