Road Testing and Pre-Inspections

Road testing is an essential step in the diagnostic process that must not be overlooked. Along with diagnostic information obtained from the DRB Scan Tool and the original customer concern, the Road Test helps to verify the problem and observe operation under actual vehicle driving conditions.

Just as important as the Road Test is, there are preliminary inspections that should be carried out prior to the Road Test. Always check the fluid level and condition before going on a Road Test or performing other tests. Also try to determine the type of fluid being used. Improper fluid can result in problems. Additionally, a variety of complaints can be caused by incorrect fluid level. Some of the conditions caused by incorrect fluid level are as follows:
- Delayed engagement
- Poor shifting or erratic shifts
- Excessive noise
- Overheating

The next step is to verify that the shift linkage is correctly adjusted. If the gearshift linkage is incorrectly adjusted because of wear or incorrect adjustment, a number of complaints can result.

The TCM monitors the Shift Lever Position (SLP) sensor at all times. If the linkage is incorrectly adjusted, the TCM may sense a shift lever position that is not correct for the gear range chosen by the driver. This may cause diagnostic trouble codes to be set and a possible limp-in situation.

The following complaints may also be the result of an incorrectly adjusted or worn linkage:
- Delayed clutch engagement or erratic shifts
- Vehicle able to drive in Neutral
- Engine not able to crank in Park or Neutral
- Gearshift linkage able to be shifted without the key in the ignition
- Not able to remove the ignition key in Park
- Parking pawl not engaging

The shift linkage should also be adjusted when replacing the transaxle, repairing the valve body or repairing any component between the shift lever and the transaxle.

Some questions to ask yourself when considering the Road Test are listed below:
- Is the complaint or concern what you think it is, based on the driver's description of the problem?
- Is the transaxle operating normally, or is there a real problem?
- When does the malfunction occur?
- Is the problem in only one gear range?
- What temperature does the complaint occur?
- Is the transaxle in limp-in mode?