Without Scan Tool

Diagnostic Connector Identification:

Voltmeter Output Waveform:

Diagnostic Connector:

1. Connect an analog voltmeter to the ground and the transmission self diagnosis output pin of the diagnostic connector.
2. Set the ignition switch to "ON".
3. Note the pattern of pulses displayed on the voltmeter. If the voltmeter indicates a steady voltage (either 0 volts or 12 volts) the TCM has failed.
4. Refer to the diagnostic codes chart to determine which device is causing the malfunction code.
5. Test and repair the offending components as necessary.
6. Clear the malfunction codes by disconnecting the vehicle battery negative terminal for ten seconds or longer.
7. Road test the vehicle and recheck for newly stored diagnostic codes.
8. After the cause of a failure code has been detected and corrected the diagnostic code memory of the TCM should be cleared by disconnecting the vehicle battery for 10 seconds or more.


The voltmeter needle will deflect for a particular duration and a certain number of times.
FOR EXAMPLE:
Code 13
The needle will deflect one time for approximately 1.5 seconds. This will represent one module of ten. There will be approximately a two second delay and then the needle will deflect three times for approximately 0.5 seconds with 0.5 second delay between deflections. This will represent three modules of one.
Code 24
The needle will deflect two times for approximately 1.5 seconds each with approximately 0.5 second delay between deflections. This will represent two modules of ten. There will be approximately a two second delay and then the needle will deflect four times for approximately 0.5 seconds with 0.5 second delay between deflections. This will represent four modules of one.