Road Test

Some 4L30-E automatic transmission complaints 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 Transmission Control Module (TCM) trouble code. Perform this procedure before each 4L30-E automatic transmission repair, and again after repairs are made.

PROCEDURE

- Duplicate the condition under which the customer's complaint was observed.
- Depending on the complaint, line pressure gauge and the Tech-1 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 4 seconds and then goes out and remains out. If the lamp stays on, connect the Tech-1 and check for trouble codes. If none are present, see Chart 1: DIAGNOSTIC CONNECTOR AND VOLTAGE SUPPLY TEST.
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.

NOTE: On 1991 vehicles, use the F-3 snapshot mode for best results. Some 1990 Troopers with later TCMs will allow snapshot mode use.

3. If, during the test drive, the "CHECK TRANS" lamp comes on, use the Tech-1 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 TCM 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 "D", the vehicle operates in fourth gear.

If the problem still exists with the TCM disconnected, check for mechanical/hydraulic problems.

5. If no problem has been found at this point, check all underhood connections that supply power to the TCM and ignition fuses. Physically and visually inspect all the TCM harness connectors for loose or corroded terminals. Inspect the TCM ground points.