General Diagnosis Procedure
IntroductionThe systematic troubleshooting information covered by this Article offers a practical and systematic approach to diagnosing 4L30-E transmission, using information that can be obtained from road tests, electrical diagnosis, oil pressure checks or noise evaluation.
The key to correcting a complaint is to make use of all of the available symptoms and logically letting them direct you to the cause.
When dealing with automatic transmission complaints, it is best to gather as many symptoms as possible before making the decision to remove the transmission from the vehicle.
Frequently, the correction of the complaint does not require removal of the transmission from the vehicle.
Driver Information
To analyze the problem fill out a complete description of the owner's complaint.
Form
Please draw a circle around the right information and complete the following form. (The next image is an example of a completed form). You can draw a circle around many numbers if you are not sure.
Example of form completed
General Diagnosis Procedure
Preliminary Inspection Chart
Checking Transmission Fluid Level and Condition
Checking fluid level and condition (color and odor) at regular intervals will provide early diagnosis information about the transmission. This information may be used to correct a condition that, if not detected early, could result in major transmission repairs.
IMPORTANT: When new, automatic transmission fluid is red in color. As the vehicle is driven, the transmission fluid will begin to look darker in color. The color may eventually appear light brown.
A dark brown color with burnt odor may indicate excessive fluid deterioration and signal a need for fluid change.
Fluid Level
When adding or changing fluid, use only DEXRON(R) III.
CAUTION! DO NOT OVERFILL.
Overfilling will cause foaming, loss of fluid, abnormal shifting and possible damage to the transmission.
1. Park the vehicle on level ground and apply the parking brake firmly.
2. Check fluid level with engine running at idle.
Notice: Be sure that transmission fluid temperature is below 30°C (86°F).
3. Move the selector lever through all gear ranges.
4. Move the selector lever to "Park".
5. Let engine idle for 3 minutes and open the overfill screw (1).
6. Add released transmission fluid until it flows out over the overfill screw opening.
7. Let engine idle until a fluid temperature between 32°C (9O°F) and 57°C (135°F) is reached, then close the overfill screw (1).
Torque: 38 Nm (28 ft. lbs.)
Notice: To prevent fluid leaks, the overfill screw and oil drain screws gasket must be replaced each time these screws are removed.
Notice: Check transmission fluid temperature with scan tool.
Minimum fluid level: 57°C (135°F)
Maximum fluid level: 32°C (90°F)
CAUTION! Do not open overfill screw with engine stopped.
CAUTION! DO NOT CHECK FLUID LEVEL UNDER THESE CONDITIONS:
^ Immediately after driving at sustained highway speeds.
^ In heavy city traffic during hot weather.
^ If vehicle is towing a trailer.
If the vehicle has been operated under these conditions, shut the engine off and allow the vehicle to "cool" for thirty (30) minutes. After the cool down period, restart the vehicle and continue from step 2 above.
Fluid Condition
^ Fluid should be changed according to maintenance schedule.
Test Driving
Some 4L30-E automatic transmission complaint 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 (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, the line pressure gauge and the 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 seconds and then goes out and remains out.
^ If the lamp is flashing, GO TO Check Trans Indicator in Transmission Control System.
^ If no serial data is present, GO TO OBD System Check. Refer to Powertrain Management.
^ If the lamp stays ON or stays OFF, GO TO "Check Trans" Check in Transmission Control System.
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 scan tool 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 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 "D", the vehicle operates in fourth gear.
If the problem still exists with the PCM disconnected, refer to Mechanical/Hydraulic Diagnosis. Refer to "Diagnosis-Preliminary".
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.