For 1990-2009 cars

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:

• | Electrical Function Check

• | Upshift Control and Torque Converter Clutch (TCC) Apply

• | Part Throttle Downshifts

• | Manual Downshifts

• | Coasting Downshifts

• | Manual Gear Range Selection

- | REVERSE

- | Driver Shift Control

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.

• | Transmission fluid level is correct. Refer to Transmission Fluid Check.

• | Tire pressure is correct.

During the road test:

• | Perform the test only when traffic conditions permit.

• | Operate the vehicle in a controlled, safe manner.

• | Observe all traffic regulations.

• | View the scan tool data while conducting this test.

| Take along qualified help in order to operate the vehicle safely.

• | Observe any unusual sounds or smells.

After the road test, check the following:

• | Inspect for proper transmission fluid level. Refer to Transmission Fluid Check.

• | 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.

• | Inspect for fluid leaks. Refer to Fluid Leak Diagnosis.

### 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.

1. Connect the scan tool.
2. Ensure the gear selector is in PARK and set the parking brake.
3. Start the engine.
4. Verify that the following scan tool data can be obtained and is functioning properly.

Refer to Control Module References for typical data values. Data that is questionable may indicate a concern.

• | Engine Speed

• | Transmission ISS

• | Transmission OSS

• | Vehicle Speed

• | IMS

• | Commanded Gear

• | Gear Ratio

• | Line PC Sol. Pressure Cmd.

• | TCC Brake Switch

• | ECT, Engine Data List

• | Trans. Fluid Temp.

• | TCM Temperature

• | Calc. Throttle Position

• | Ignition Voltage

• | TFP Switch 1

• | TFP Switch 2

• | TFP Switch 3

• | TFP Switch 4

• | PC Sol. 2 Pressure Cmd.

• | PC Sol. 3 Pressure Cmd.

• | PC Sol. 4 Pressure Cmd.

• | PC Sol. 5 Pressure Cmd.

• | Shift Solenoid

• | TCC PC Sol. Duty Cycle

• | TCC Slip Speed

5. 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.

6. Check the garage shifts.

6.1. | Apply the brake pedal and ensure the parking brake is set.

6.2. | Move the gear selector through the following ranges:

6.2.1. | PARK to REVERSE

6.2.2. | REVERSE to NEUTRAL

6.2.3. | NEUTRAL to DRIVE

6.3. | Pause 2 to 3 seconds in each gear position.

6.4. | Verify the gear engagements are immediate and not harsh.

Note: Harsh engagement may be caused by any of the following conditions:

• | High engine idle speed--Compare engine idle speed to desired idle speed.

• | Commanded low pressure control (PC) solenoid current--Investigate PC Sol. Pressure Cmd. kPa (psi) for all solenoids. 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 fluid level

• | Commanded high PC solenoid current--Investigate PC Sol. Pressure Cmd. kPa (psi) for all solenoids. 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.

7. Monitor transmission range on the scan tool, engine data list.

7.1. | Apply the brake pedal and ensure the parking brake is set.

7.2. | Move the gear selector through all ranges.

7.3. | Pause 2 to 3 seconds in each range.

7.4. | Return gear selector to PARK.

7.5. | Verify that all selector positions match the scan tool display.

8. Check throttle position input.

8.1. | Apply the brake pedal and ensure the parking brake is set.

8.2. | Ensure the gear selector is in PARK.

8.3. | 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.

### Upshift Control and Torque Converter Clutch (TCC) Apply

The TCM calculates the upshift points based primarily on 2 inputs: throttle position and vehicle speed. When the TCM determines that conditions are met for a shift to occur, the TCM commands the shift by closing or opening the ground circuit for the appropriate solenoid.

Perform the following steps:

1. Monitor the following scan tool parameters:

• | Calc. Throttle Position

• | Vehicle Speed

• | Engine Speed

• | Transmission ISS

• | Transmission OSS

• | Commanded Gear

• | TCC PC Sol. Pressure Cmd.

• | TCC Pressure Actual

• | TCC Slip Speed

• | TFP Switch 1

• | TFP Switch 2

• | TFP Switch 3

• | TFP Switch 4

• | PC Sol. 2 Pressure Cmd.

• | PC Sol. 3 Pressure Cmd.

• | PC Sol. 4 Pressure Cmd.

• | PC Sol. 5 Pressure Cmd.

• | Shift Solenoid

2. Place the gear selector in the DRIVE position.
3. Accelerate the vehicle using the chosen throttle position. Hold the throttle steady.
4. As the transmission upshifts, there should be a noticeable shift feel or engine speed change within 1 to 2 seconds of the commanded gear change. The TCC feel may not be noticeable. Look for 100-300 RPM engine speed change.
5. Compare the shift speeds to the Shift Speed table. Shift speeds may vary slightly due to TFT or other operating variables, including hydraulic delays in responding to electronic controls.

• | Note any harsh, soft or delayed shifts or slipping.

• | Note any noise or vibration.

Note:

• | This transmission is equipped with an electronically controlled capacity clutch (ECCC), which does not allow the clutch to fully lock to the torque converter cover. The clutch maintains a small amount of slippage, approximately 20 RPM, in 2nd, 3rd, 4th, 5th, and 6th gears, depending on the vehicle application. ECCC was developed to reduce the possibility of noise, vibration or chuggle caused by TCC apply. Full lockup is available at highway speeds on some applications.

• | The TCC will not engage until the engine is in closed loop operation and the vehicle speed is above a calibrated speed. The vehicle must be in a near-cruise condition, not accelerating or coasting, and on a level road surface.

6. Monitor TCC PC solenoid current while driving and make sure the current rises when the TCC is commanded to apply.

• | When the TCC applies there should be a noticeable drop in engine speed and a drop in slip speed to below 100 RPM. If the TCC apply can not be detected:

- | Check for DTCs.

- | Refer to Torque Converter Diagnosis.

• | Apply and release the brake pedal. The TCC will release on most applications.

### Part Throttle Downshift

1. Place the gear selector in the DRIVE position.
2. Accelerate the vehicle to 64-88 km/h (40-55 mph) in 6th gear.
3. Quickly increase throttle angle to between 25-30 percent.
4. Verify the following:

• | The TCC releases.

• | The transmission downshifts immediately.

### Manual Downshifts

Manual downshift testing is not required for vehicles equipped with Driver Shift Control (DSC). The TCM and shift solenoids will automatically override DSC downshifts to protect the transmission from damage.

#### Coasting Downshifts

1. Place the gear selector in the DRIVE position.
2. Accelerate the vehicle to 6th gear with the TCC applied.
3. Release the throttle and apply the brakes
4. Verify the following:

• | The TCC releases (on most applications).

• | Downshifts occur as commanded.

### Reverse

Perform the following test using a 10-15 percent throttle position.

1. With the vehicle stopped, move the gear selector to REVERSE.
2. Slowly accelerate the vehicle.
3. Verify that there is no noticeable slip, noise or vibration.

### Driver Shift Control (DSC) / Electronic Range Selection (ERS)

Refer to the owner's manual for specific instructions on DSC/ERS. The TCM will upshift automatically when maximum engine speed is achieved and will protect from any downshift which may cause excessive engine RPMs.