For 1990-2009 cars

The transmission control module (TCM) calculates upshift points based primarily on 2 inputs: throttle angle and vehicle speed. When the TCM wants a shift to occur, an electrical signal is sent to the shift solenoids which in turn move the valves to perform the upshift.

The shift speed charts reference throttle angle instead of 'min throttle' or 'wot' to make shift speed measurement more uniform and accurate. Use a scan tool to monitor the throttle angle.

### Upshift Procedure

1. Place the gear selector in Drive (D).
2. Choose a percent throttle angle of 10 percent or 25 percent. Refer to Shift Speed .
3. Set up the scan tool to monitor the throttle angle and the vehicle speed.
4. Accelerate to the chosen throttle angle and hold the throttle steady.

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

Note when the torque converter clutch (TCC) applies. This should occur in fourth gear. If the apply is not noticed by a drop in RPM, refer to Torque Converter Diagnosis . The lockup clutch should not apply unless the transaxle has reached a minimum operating temperature of 8°C (46°F) and an engine coolant temperature of 50°C (122°F).
5. As the transaxle upshifts, note the shift speed and the commanded gear changes for each of these gears:

• | Second gear

• | Third gear

• | Fourth gear

6. Repeat steps 2-5 using several different throttle angles.

### Part Throttle Detent Downshift

At vehicle speeds of 55-65 km/h (34-40 mph) in Fourth gear, quickly increase the throttle angle to greater than 50 percent. Verify the following conditions:

• | The TCC applies.

• | The transaxle downshifts to Third gear.

• | Solenoid 1 turns ON to OFF.

• | Solenoid 2 turns OFF.

### Full Throttle Detent Downshift

At vehicle speeds of 55-65 km/h (34-40 mph) in Fourth gear, quickly increase the throttle angle to the maximum 100 percent position. Verify the following conditions:

• | The TCC releases.

• | The transaxle downshifts to Second gear immediately.

• | Solenoid 1 turns ON to OFF.

• | Solenoid 2 turns OFF.

### Manual Downshifts

1. At vehicle speeds of 60 km/h (40 mph) in Fourth gear, release the accelerator pedal while moving the gear selector lever to Manual Third. Observe the following conditions:

• | The transaxle downshifts to Third gear immediately.

• | The engine slows the vehicle down

Important: A manual First-Third Gear Ratio will occur at high speeds as an upshift safety feature. Do NOT attempt to perform this shift.

2. Move the gear selector back to Overdrive and accelerate to 50 km/h (31 mph). Release the accelerator pedal and move the gear selector lever to Manual First. Observe the following conditions:

• | The transaxle downshifts to Second gear immediately.

• | The engine slows the vehicle down

### Coasting Downshifts

1. With the gear selector in Overdrive, accelerate to Fourth gear with the TCC applied.
2. Release the accelerator pedal and lightly apply the brakes. Observe the following conditions:

• | The TCC releases.

• | Downshifts occur at speeds shown on the shift speed chart. Refer to Shift Speed .

### Manual Gear Range Selection

Upshifts in the manual gear ranges are controlled by the shift solenoids. Perform the following test by accelerating at 25 percent TP sensor increments.

#### Manual Third (3)

With the vehicle stopped, move the gear selector to Manual Third and accelerate. Observe the 1-2 shift and the 2-3 shift.

#### Manual Second (2)

With the vehicle stopped, move the gear selector to Manual Second and accelerate. Observe the 1-2 shift.

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 and accelerate to 30 km/h (19 mph). Observe that no upshifts occur.

#### Reverse (R)

With the vehicle stopped, move the gear selector to Reverse. Observe that solenoid 1 and solenoid 2 are both OFF.

Use a scan tool to see if any transaxle trouble codes have been set. Refer to Diagnostic Trouble Code (DTC) List/Type and repair the vehicle as directed. After repairing the vehicle, road test the vehicle and verify that the code has not set again.

If the transaxle is not performing well and no trouble codes have been set, an intermittent condition may be occurring. Inspect all electrical connections for damage or for a loose fit. You may also perform a snapshot test which can help to catch an intermittent condition that does not occur long enough to set a code.

Refer to Electronic Component Description to become familiar with transaxle conditions caused by transaxle electrical malfunction.

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