94-95 Models

Shift Speed Chart - Normal Mode:

Shift Speed Charts - Power And Winter Modes; Lock-up Speed Chart:

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 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.

IMPORTANT:
- Duplicate the condition under which the 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 2 to 3 seconds and then goes out and remains out.
- If the lamp stays ON, connect the TECH 1 and check for trouble codes.
Displaying and Reading Trouble Codes
- If none are present, see "Chart 1 - Diagnosis Connector and Voltage Supply Test".
Chart 1 - Diagnosis Connector and Voltage Supply Test

NOTE: Remember that, when TECH 1 is connected, line pressure will be at maximum during shifts.

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. (Refer to the shift and lock-up timing charts at top of page.) 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 TECH 1 to check for trouble codes.
Displaying and Reading 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 persists with the TCM disconnected, refer to "Hydraulic/Mechanical System Tests".
Hydraulic/Mechanical System Tests

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.