Important: The Road Test procedure should be performed only as part of the symptom diagnosis. Refer to Symptoms - Automatic Transmission in this section.

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:

Before the road test, ensure the following:

During the road test:

After the road test, inspect for the following:

Perform this check first in order to ensure that the electronic transmission components are connected and functioning properly. If these components are not checked, a simple electrical condition could be misdiagnosed.

1. Connect a Tech 2 to the DLC.
2. Ensure the shift selector is in Park and firmly apply the parking brake.
3. Start the engine and allow to idle.
4. Verify that the following Tech 2 data parameters can be obtained and are functioning properly. Refer to Scan Tool Data List for typical data values. Data that is questionable may indicate a concern.

•	Engine speed

•	Transmission output speed

•	Vehicle speed

•

IMS range

•	Transmission range (engine list)

•	Commanded gear

•	PC solenoid reference current

•	PC solenoid actual current

•	PC solenoid duty cycle

•	Brake switch

•	Engine coolant temperature

•	Transmission fluid temperature

•	Accelerator pedal position

•	Ignition voltage

•	1-2 shift solenoid

•	2-3 shift solenoid

•	4-5 shift solenoid

•	TCC solenoid duty cycle

•	TCC slip speed

5. Monitor the brake switch signal while depressing and releasing the brake pedal. The Tech 2 should display:

•	Open when the brake pedal is released

•	Closed when the brake pedal is depressed

6. Check the garage shifts.

•	Apply the brake pedal and ensure that the parking brake is set.

•	Move the gear selector through the following ranges:

-	Park to Reverse

-	Reverse to Neutral

-	Neutral to Drive

•	Pause 2-3 seconds in each gear position.

•	Verify the gear engagements are immediate and not harsh.

•	High engagement may be caused by any of the following conditions:

-	High idle speed--Compare the engine idle speed to the desired idle speed.

-	Commanded low PC solenoid current--Compare the PC solenoid reference current to the PC solenoid actual current.

-	A default condition caused by certain DTCs that result in maximum line pressure to prevent slippage

•	Soft or delayed engagement may be caused by any of the following conditions:

-	Low idle speed--Compare the engine idle speed to the desired idle speed.

-	Low fluid level

-	Commanded high PC solenoid current--Compare the PC solenoid reference current to the PC solenoid actual current.

-	Cold transmission fluid--Inspect for low transmission fluid temperature.

-	Selector linkage--Inspect the adjustment.

7. Monitor the transmission range on the Tech 2 engine list. Apply the brake pedal and ensure that the parking brake is set.

•	Move the gear selector through all ranges.

•	Pause for 2-3 seconds in each range.

•	Return the gear selector to Park.

•	Verify that all selector positions match the scan tool display.

8. Check the accelerator pedal input. Apply the brake pedal and ensure that the parking brake is set.

•	Ensure that the gear selector is in Park.

•	Monitor the accelerator pedal while increasing and decreasing the engine speed with the throttle pedal. The Tech 2 Throttle Position display should increase and decrease with the engine speed.

If any of the above checks do not perform properly, record the result for reference after completion of the road test.

The TCM calculates the upshift points based primarily on two inputs; throttle angle and vehicle speed. When the TCM determines that conditions are met for a shift to occur, it will command the shift by closing or opening the ground circuit for the appropriate solenoid.

Preliminary Checks

1. Refer to Shift Speed in this section and choose a throttle position of 12 percent, 25 percent, or 50 percent. All throttle angles shown should be tested to cover the normal driving range.
2. Monitor the following Tech 2 data parameters:

•	Throttle angle

•	Vehicle speed

•	Engine speed

•	Output shaft speed

•	Commanded gear

•	Slip speed

•	Solenoid states

3. Place the gear selector in the Dive (D) position.
4. Accelerate the vehicle using the chosen throttle angle. Hold the throttle steady.
5. As the transmission upshifts, note the vehicle speed when the shift occurs for each gear change. There should be a noticeable shift feel or engine speed change within 1-2 seconds of the commanded gear change.
6. Compare the shift speeds to the shift speed charts in this section. Refer to Shift Speed. Shift speeds may vary slightly due to adaptive learn parameters, transmission fluid temperature, or hydraulic delays in responding to the electronic controls.

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

•	Note any noise or vibrations.

7. Repeat steps 1-6 to complete all throttle angles.

Important: 

•

The transmission is equipped with an electronically controlled capacity clutch (ECCC). The pressure plate does not fully lock to the torque converter cover. The pressure plate maintains a small amount of slippage, approximately 20 RPM in 3rd, 4th, and 5th gears. The ECCC was developed to reduce the possibility of noise, vibration, or chuggle caused by TCC apply. Typical apply speeds are 49-52 km/h in 3rd gear, and 65-73 km/h in 4th gear. Full lockup does occur at highway speeds.

•	The TCC will not engage until the engine is in Closed Loop operation and the vehicle speed is as shown in the shift speed charts in this section. Refer to Shift Speed. The vehicle must be in a near-cruise condition, not accelerating or coasting, and on a level road surface.

8. Check for TCC apply in 3rd, 4th, and 5th gears.

•	Note the TCC apply point. 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 in this section.

•	Refer to Shift Speed in this section for the correct apply speeds.

•	Lightly tap and release the brake pedal. The TCC should release.

1. Place the gear selector in the Overdrive position.
2. Accelerate the vehicle to 64-88 km/h in 5th gear.
3. Quickly increase throttle angle to greater than 50 percent.
4. Verify the following:

•	The TCC releases

•	The transmission downshifts immediately to 4th gear

5. Place the gear selector in the Overdrive position.

1. Accelerate the vehicle to speeds of 64-88 km/h in 5th gear.
2. Quickly increase throttle angle to 100 percent (wide open throttle).
3. Verify the following:

•	The TCC releases

•	The transmission downshifts immediately to 3rd gear

The shift solenoid valves control the initial downshift for the 5-4, 4-3, 3-2 manual downshifts. The solenoid states should change during or shortly after a manual downshift is selected.

Manual 5-4 Downshift

1. Place the gear selector in the D position.
2. Accelerate the vehicle to 64-88 km/h in 5th gear.
3. Release the throttle while moving the gear selector to 4th.
4. Check that the following occurs:

•	The TCC releases

•	The transmission downshifts immediately to 4th gear

•	The engine slows the vehicle

Manual 5-3 Downshift

1. Place the gear selector in the D position.
2. Accelerate the vehicle to 64-72 km/h.
3. Release the throttle while moving the gear selector to 3rd.
4. Check that the following occurs:

•	The TCC releases

•	The transmission downshifts immediately to 3rd gear

•	The engine slows the vehicle

Manual 5-2 Downshift

1. Place the gear selector in the D position.
2. Accelerate the vehicle to 48 km/h.
3. Release the throttle while moving the gear selector to 2nd.
4. Check that the following occurs:

•	The TCC releases

•	The transmission downshifts immediately to 2nd gear

•	The engine slows the vehicle

Coasting Downshifts

1. Place the gear selector in the D position.
2. Accelerate the vehicle to 5th gear with the TCC applied.
3. Release the throttle and lightly apply the brakes.
4. Verify the following:

•	The TCC releases

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

The shift solenoids control the upshifts in the manual gear ranges. Perform the following tests using 10-15 percent throttle angle:

Reverse

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.

Manual Second

1. With the vehicle stopped, move the gear selector to 2nd.
2. Accelerate the vehicle to 32 km/h.
3. Verify the following:

•	No upshifts occur

•	The TCC does not apply

•	There is no noticeable slip, noise, or vibration

Manual Third

1. With the vehicle stopped, move the gear selector to 3rd.
2. Accelerate the vehicle to 57 km/h.
3. Verify the following:

•	The 1-2 shift occurs

•	The 2-3 shift does not occur

•	There is no noticeable slip, noise, or vibration

Manual Fourth

1. With the vehicle stopped, move the gear selector to 4th.
2. Accelerate the vehicle to 64 km/h.
3. Verify the following:

•	The 1-2 shift occurs

•	The 2-3 shift occurs

•	There is no noticeable slip, noise, or vibration