Procedure

NOTE: Some 4L30-E automatic transmission complaints vehicles will require a test drive as a part of the diagnostic procedure. Some codes will not set unless the vehicle is moving. The purpose of the test drive is to duplicate the customer's complaint condition and set a current Powertrain Control Module ([1][2]PCM)trouble code. Perform this procedure before each 4L30-E automatic transmission repair, and again after repairs are made.

IMPORTANT:
^ Duplicate the condition under which the customer's complaint was observed.
^ Depending on the complaint, line pressure gauge and the TECH1 scan tool may be required during the test drive.
^ During the test drive, it is important to record all necessary data from the areas being monitored, for use in diagnosis. Also listen for and note any unusual noises.

The following procedure should be used to test drive 4L30-E automatic transmission complaint vehicles:
1. Turn the ignition ON without starting the engine. Check that the "CHECK TRANS" lamp comes on for approximately 2 to 3 seconds and then goes out and remains out.
- If the lamp is flashing, Go to CHECK TRANS INDICATOR.
- If no serial data is present, Go to OBD System Check. Computers and Control Systems
- If the lamp stays ON or stays OFF, Go to "CHECK TRANS" CHECK.
2. Drive the vehicle. During the test drive be sure that the transmission achieves normal operating temperature (approx. 20 minutes). Allow the transmission to go through all of its gear ranges, checking shift timing and firmness. Duplicate the owner's complaint condition as closely as possible during the test drive.
3. If, during the test drive, the "CHECK TRANS" lamp comes on, use the TECH1 to check for trouble codes.
4. If, during the test drive, a problem is felt, but the "CHECK TRANS" lamp does not come on and no trouble codes are present, drive the vehicle with the [1][2]PCM disconnected (manually shifting the vehicle).
- In manual L, the vehicle operates in first gear.
- In manual 2, the vehicle operates in third gear.
- In manual 3 or HO", the vehicle operates in fourth gear.
If the problem still exists with the [1][2]PCM disconnected, refer to the HYDRAULIC DIAGNOSIS. [1][2]- Mechanical/Hydraulic Diagnosis Symptom Charts
5. If no problem has been found at this point, check all underhood connections that supply power to the PCM and ignition fuses. Physically and visually inspect all the PCM harness connectors for loose or corroded terminals. Inspect the PCM ground points.