Diagnostic System Check - Transmission Codes

PCM ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK


Circuit Description:

The "PCM OBD System Check" is an organized approach to identifying a problem created by an electronic control system malfunction. It must be the starting point for any automatic transaxle diagnosis because it directs the service technician to the next logical step in diagnosing the complaint. Understanding the chart and using it correctly, will reduce diagnostic time and prevent the replacement of good components.

Note: that the PCM self-diagnostic mode can only be initiated if the "OVERDRIVE"switch button is depressed.


Test Description:

Numbers(s) below refer to the circled number(s) on the Diagnostic Chart.

1. This checks to see if the "O/D OFF" Indicator will light.

2. This checks to see if the "O/D OFF" Indicator goes out.

3. This checks the PCM's self-diagnostic system for a possible failure.

4. This checks to see if there are any DTC's present.

5. This checks for faulty self-diagnostic system wiring and for a faulty PCM.

6. This checks the throttle position output circuit for the Throttle Position (TP) sensor.

7. This checks to see if the DTC's are intermittent or hard faults.

8. This checks the Stoplamp switch circuit for the [1][2]Torque Converter Clutch (TCC) lockup interruption.

9. This checks the transaxle shift pattern and the Park Neutral Position (PNP) switch circuit.


Diagnostic Aids:

Check GAUGE Fuse for an open, and grounds for clean tight connections.

Check for poor connections at component and inline harness connector terminal connections before replacing components.

After repairs have been made, repeat the PCM OBD System Check to ensure the system is functioning normally.