Diagnosis With TECH1

NOTE: Perform the preliminary inspection first!

This information is designed to aid troubleshooting electrical faults using the Tech-1 scan tool. If the "CHECK TRANS" indicator is illuminated, or if a transmission electrical fault is suspected, use the Tech-1 to check for trouble codes. The diagnostic procedures rely on correcting problems indicated by trouble codes, in numerical order, before attempting to diagnose problems not indicated by trouble codes.

Proper diagnosis of a fault requires that lower numbered trouble code repair procedures be performed before higher numbered trouble code repair procedures. For example, if both Code 23 and Code 41 are present, work on code 23 first.

When using the Tech-1 scan tool to check for trouble codes:

1. If no codes are set, refer to F0: DATA LIST QUICK CHECK to identify electrical faults not indicated by trouble codes.
2. If codes are set:
- Write down all codes displayed on Tech-1, note if the code is intermittent.
- Clear the codes.
- Test drive the vehicle in a manner which attempts to repeat the failure condition.
- Recheck for trouble codes using the Tech-1.
- If a code does not reappear after the test drive, the failure is intermittent.
- If a code is present, refer to CHART 2 for diagnosis.
- Repair codes in increasing numeric order, since failures which set lower numbered codes may also set higher numbered codes.
- CHART 2 is organized assuming the code which is being diagnosed is the LOWEST numbered code present.