For 1990-2009 cars

• | Perform this test using a scan tool.

• | Perform this test only when traffic and road conditions permit.

• | Observe all traffic safety regulations.

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

With the gear selector in Overdrive (D), perform the following steps:

1. Refer to the Shift Speed table contained in this section and choose a throttle position of either 10% or 25%.
2. Monitor the throttle angle and the vehicle speed with the scan tool.

Important: Shift speeds may vary due to slight hydraulic delays in responding to electronic controls. A change from the original equipment tire size also affects shift speeds.

3. Accelerate to the chosen throttle angle. Hold the throttle steady.
4. As the transmission upshifts, note the shift speed and the commanded gear changes for each of the following gears:

• | 2nd gear

• | 3rd gear

• | 4th gear

Important: The TCC should not apply unless the transmission has reached a minimum operating temperature of 8°C (46°F) Trans Temp and 50°C (122°F) Engine Coolant Temp.

5. The Torque Converter Clutch (TCC) should apply in Fourth gear. Note when the TCC applies. If you do not notice the apply by an RPM drop, refer to Torque Converter Clutch Diagnosis .
6. Repeat steps 1-5 using several different throttle angles.

### Part Throttle Detent Downshift

At vehicle speeds of 64-88 km/h (40-55 mph) in Fourth gear, quickly increase the throttle angle to greater than 50%. Verify the following results:

• | The TCC releases.

• | The transmission downshifts to 3rd gear.

• | The 1-2 Shift Solenoid valve turns OFF.

• | The 2-3 Shift Solenoid valve remains ON.

### Full Throttle Detent Downshift

At vehicle speeds of 64-88 km/h (40-55 mph) in Fourth gear, quickly increase the throttle angle to its maximum position. Verify the following results:

• | The TCC releases.

• | The transmission downshifts to 2nd gear immediately.

• | The 1-2 and 2-3 Shift Solenoid valves turn OFF.

### Manual Downshifts

The shift solenoid valves do not control the initial 4-3 manual downshift. The 4-3 manual downshift is hydraulic. The 3-2 and the 2-1 manual downshifts are electronic. The solenoid states will change during, or shortly after, a 4-3 downshift is selected.

1. At vehicle speeds of 64-88 km/h (40-55 mph) in Fourth gear, release the accelerator pedal while moving the gear selector to Manual Third (3). Observe the following results:

• | The TCC releases.

• | The transmission downshifts to 3rd gear immediately.

• | The engine slows the vehicle down.

2. Move the gear selector back to Overdrive (D) and accelerate to 64-72 km/h (40-45 mph). Release the accelerator while moving the gear selector to Manual Second (2) and observe the following results:

• | The TCC releases.

• | The transmission immediately downshifts to 2nd gear.

• | The engine slows the vehicle down.

3. Move the gear selector back to Overdrive and accelerate to 64 km/h (40 mph). Release the accelerator pedal while moving the gear selector to Manual First (1) and observe the following results:

• | The TCC releases.

• | The transmission immediately downshifts to 2nd gear.

• | The engine slows the vehicle down.

• | Below 60 km/h (37 mph) the transmission downshifts to 1st gear.

A Manual First-Third Gear Ratio will occur at high speeds as an upshift safety feature. Do not attempt to perform this shift.

### Coasting Downshifts

1. With the gear selector in Overdrive (D), accelerate to 4th gear with the TCC applied.
2. Release the accelerator pedal and lightly apply the brakes. Observe the following results:

• | The TCC releases.

• | Downshifts occur at speeds shown in the Shift Speed table. Refer to Shift Speed .

### Manual Gear Range Selection

The shift solenoids control the upshifts in the manual gear ranges.

Perform the following tests by accelerating at 10% TP sensor position.

#### Manual Third (3)

With the vehicle stopped, move the gear selector to Manual Third (3) and accelerate in order to observe the following conditions:

• | The 1-2 shift

• | The 2-3 shift

#### Manual Second (2)

1. With the vehicle stopped, move the gear selector to Manual Second (2) and accelerate in order to observe the 1-2 shift.
2. Accelerate to 40 km/h (25 mph) and observe the following conditions:

• | The 2-3 shift does not occur.

• | The TCC does not apply.

#### Manual First (1)

With the vehicle stopped, move the gear selector to Manual First (1). Accelerate to 32 km/h (20 mph) and observe the following conditions:

• | No upshifts occur.

• | The TCC does not apply.

#### Reverse (R)

With the vehicle stopped, move the gear selector to R and slowly accelerate in order to observe the following conditions:

• | The 1-2 Shift Solenoid valve is ON.

• | The 2-3 Shift Solenoid valve is OFF.

Use a scan tool to see if any transmission trouble codes are set. Refer to Diagnostic Trouble Codes and repair the vehicle as directed. After repairing the vehicle, perform the hoist test and verify that the code did not set again.

If the transmission is still not performing well but no trouble codes have set, there may be an intermittent condition. Check all electrical connections for damage or a loose fit. Some scan tools have a snapshot test which can help catch an intermittent condition that does not occur long enough to set a code.

Refer to Electronic Component Description in order to become familiar with transmission conditions caused by transmission electrical malfunctions.

If no trouble codes set and the condition is suspected to be hydraulic, take the vehicle on a road test.