Note: The Road Test Procedure should be performed only as part of the Symptom Diagnosis. Refer to
Symptoms - Automatic Transmission.
The following test provides a method of evaluating the condition of the automatic transmission. The test is structured so that most driving conditions would be achieved. The test is divided into the following parts:
| • | Visual Inspection of Transmission Fluid Leaks |
| • | Electrical Function Check |
| • | Confirm Customer Complaint by Driving |
| • | Check Oil Level and Oil Quality |
Note: Complete the test in the sequence given. Incomplete testing cannot guarantee an accurate evaluation.
Before the road test, ensure the following:
| • | The engine is performing properly. |
| • | Tire pressure is correct. |
| • | Vent hose is correctly mounted |
During the road test:
| • | Perform the test only when traffic conditions permit. |
| • | Operate the vehicle in a controlled, safe manner. |
| • | Observe all traffic regulations. |
| | Note: Take along qualified help in order to operate the vehicle safely.
|
| • | View the scan tool data while conducting this test. |
| • | Observe any unusual sounds or smells. |
After the road test, check the following:
| • | Inspect for any diagnostic trouble codes (DTCs) that may have set during the testing. Refer to the applicable DTC. |
| • | Monitor the scan tool data for any abnormal readings or data. |
Electrical Function Check
Perform this procedure first in order to ensure the electronic transmission components are functioning properly. If these components are not checked, a simple electrical condition could be misdiagnosed.
- Connect the scan tool.
- Ensure the gear selector is in PARK and set the parking brake.
- Start the engine.
- Verify that scan tool data can be obtained. Refer to
Control Module References for typical data values. Data that is questionable may indicate a concern.
- Monitor the TCC Brake Switch parameter while applying and releasing the brake pedal. The scan tool should display:
| • | Open when the brake pedal is applied. |
| • | Closed when the brake pedal is released. |
- Check the garage shifts.
| • | Apply the brake pedal and ensure the parking brake is set. |
| • | Move the gear selector through the following ranges: |
| • | Pause 2 to 3 seconds in each gear position. |
| | Note: Harsh engagement may be caused by any of the following conditions:
| • | Verify the gear engagements are immediate and not harsh. |
| • | High engine idle speed-Compare engine idle speed to desired idle speed. |
| • | High pressure will cause harsh shifts. |
| • | A default condition caused by certain DTCs that result in maximum line pressure to prevent clutch slippage. |
|
| | Note: Soft or delayed engagement may be caused by any of the following conditions:
| • | Low idle speed--Compare engine idle speed to desired idle speed. |
| • | Low pressure will cause soft or delayed shifts. |
| • | Cold transmission fluid temperature (TFT)--Use the scan tool to determine TFT. |
| • | Selector linkage--Inspect and adjust as necessary. |
|
| • | Verify the gear engagements are immediate and not harsh. |
- Monitor transmission range on the scan tool, engine data list.
| • | Apply the brake pedal and ensure the parking brake is set. |
| • | Move the gear selector through all ranges. |
| • | Pause 2 to 3 seconds in each range. |
| • | Return gear selector to PARK. |
| • | Verify that all selector positions match the scan tool display. |
- Check throttle position input.
| • | Apply the brake pedal and ensure the parking brake is set. |
| • | Ensure the gear selector is in PARK. |
| • | Monitor the scan tool Calc. Throttle Position while increasing and decreasing engine speed with the throttle pedal. The scan tool Calc. Throttle Position percentage should increase and decrease with engine speed. |
If any of the above checks do not perform properly, record the result for reference after completion of the road test.
Adaptive Learning
Start driving the car and make the adaptive learning. Refer to
Transmission Adaptive Functions.
Confirm Customer Complaint by Driving
Continue driving to verify the customer complaint. It might be useful to use manual shifting in order to verify the problem.
Check Oil Level and Oil Quality
After the driving is finalized and the complaint has been recorded:
| - | If the oil is milky there is a water leakage into the transmission. Check the vent hose. |
| - | If the oil smells burnt and its color is dark some disc may have been overloaded. |
| • | If the oil quality is too bad, change oil, make a new adaptive driving and the check if the problem is still there. |
