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Home >> Chevy Truck >> 2004 >> Tracker 4WD L4-2.0L VIN C >> Repair and Diagnosis >> Transmission and Drivetrain >> Automatic Transmission/Transaxle >> Testing and Inspection >> Initial Inspection and Diagnostic Overview >> Road Test Procedure

Road Test Procedure

Road Test Procedure

Important:
^ Perform the road test following the sequence given.
^ Km/h (mph) shift points will vary with actual throttle position and driver habits
^ Engine coolant temperature must be at normal operating temperature.
^ Compare the results of the road test with the Transmission Shift Speed Schedules below. Use these results with the diagnosis information for the transmission evaluation.
^ This test should only be performed when traffic and road conditions permit.
^ Observe all traffic and safety regulations.

Drive and Reverse Engagement Test
1. Turn the ignition switch to ON.
2. Depress the brake pedal fully.
3. Place the manual selector in the Park (P) position.
4. Start the engine and warm up the engine to normal operating temperature.
5. Move the manual selector from the Park (P) position to the Neutral (N) position.
6. With a stop watch ready, move the manual selector from the Neutral (N) position to the Drive (D) position.
7. Measure the time from the moment you move the shift lever until you feel the gear engagement.
8. Move the manual selector from the Drive (D) position to the Neutral (N) position.
9. With a stop watch ready, move the manual selector from the Neutral (N) position to the Reverse (R) position.
10. Measure the time from the moment you move the shift lever until you feel the gear engagement.
11. Return the manual selector to the Park (P) position.
12. Turn the ignition switch to the LOCK position.
13. Verify that the following conditions exist:
^ The Drive engagement from the Neutral position takes approximately 1.2 seconds.
^ The Reverse engagement from the Neutral position takes approximately 1.5 seconds.
^ The reverse and the drive engagements should be immediate, but not harsh.
If the reverse and the drive engagements are slow to engage or seem too harsh, refer to Line Pressure Check Procedure for possible causes and corrections.

Upshifts and Torque Converter Clutch (TCC) Apply Test

Important: Before repeating this test, wait at least one minute after returning the manual selector to the Neutral (N) position.

1. Press the brake pedal firmly.
2. Start the engine and warm up the engine to normal operating temperature.
3. With the engine running at idle (750 - 850 RPM), move the manual selector to the Drive (D) position.
4. Set the Power/Normal switch to the Normal (N) position.
5. Release the brake pedal and accelerate the vehicle speed using steadily increasing accelerator pressure.
6. Observe the vehicle speeds and the shift points for the following gears:
^ Second gear
^ Third gear
^ Fourth gear (Overdrive)

Important: The TCC will not apply and fourth gear upshift is delayed until the engine coolant temperature has reached at least 86°C (30°F).

7. Observe the TCC apply. This should occur in either third gear or in fourth gear.
8. Stop the vehicle, set the Power/Normal switch to the Power (P) position, and repeat steps 5-7.
9. Return the manual selector to the Park (P) position and turn the ignition switch to LOCK.
10. Verify that the gear downshifts and the TCC release occur properly as shown in the shift speed tables below. If the transmission is not within specifications, refer to Line Pressure Check Procedure for possible causes and corrections.

Part Throttle Downshift Test

Power (P) Shift Mode
Test the power shift using the following procedure:
1. Operate the vehicle at 80 km/h (50 mph).
2. Verify the following driving conditions:
^ The manual selector is in the Drive (D) range
^ The OD switch is pressed
^ The Power/Normal switch is in the Power (P) position
3. Quickly press the accelerator pedal to approximately half throttle.
4. Verify the following results:
^ The TCC releases.
^ The transmission immediately downshifts to third gear.

Normal (N) Shift Mode
Test the normal shift using the following procedure:
1. Operate the vehicle at 40 km/h (25 mph).
2. Verify the following driving conditions:
^ The manual selector is in the Drive (D) range
^ The OD switch is pressed
^ The Power/Normal switch is in the Normal (N) position
3. Quickly press the accelerator pedal to approximately half throttle.
4. Verify the following results:
^ The TCC releases.
^ The transmission immediately downshifts to third gear.

Full Throttle Downshift Test

Power (P) Shift Mode
Test the power shift mode using the following procedure:
1. Operate the vehicle at 80 km/h (50 mph).
2. Verify the following conditions:
^ The manual selector is in the Drive (D) position
^ The OD switch is pressed
^ The Power/Normal switch is in the Power (P) position
3. Quickly press the accelerator pedal to the Wide Open Throttle (WOT) position.
4. Verify the following conditions:
^ The TCC releases.
^ The transmission immediately downshifts to second gear.

Normal (N) Shift Mode
Test the normal shift mode using the following procedure:
1. Operate the vehicle at 40 km/h (25 mph).
2. Verify the following conditions:
^ The manual selector is in the Drive (D) position
^ The OD switch is pressed
^ The Power/Normal switch is in the Normal (N) position
3. Quickly press the accelerator pedal to the Wide Open Throttle (WOT) position.
4. Verify the following conditions:
^ The TCC releases.
^ The transmission immediately downshifts to second gear.

Manual Downshift Test
1. At a vehicle speed of 80 km/h (50 mph), perform the following procedure:
1.1. Move the manual selector to the Drive (D) selector.
1.2. Press the OD switch.
1.3. Place the Power/Normal switch in the Power (P) position. l
1.4. Release the accelerator pedal.
1.5. Release the OD switch._
1.6. Verify the following operating conditions:
^ The TCC releases.
^ The transmission downshifts immediately to third gear.
^ The engine reduces the vehicle speed.
2. At a vehicle speed of 48 km/h (30 mph), perform the following procedure:
2.1. Move the manual selector to the Drive (D) selector.
2.2. Release the accelerator pedal.
2.3. Move the manual selector to Second (2) gear.
2.4. Verify the following operating conditions:
^ The transmission downshifts immediately to second gear.
^ The engine reduces the vehicle speed.
2.5. If no engine braking is available, test for a faulty second coast brake.
3. At a vehicle speed of 24 km/h (15 mph), perform the following procedure:
3.1. Move the manual selector to the Drive (D) selector.
3.2. Release the accelerator pedal.
3.3. Move the manual selector to the Low (L) position.
3.4. Verify the following operating conditions:
^ The transmission downshifts immediately to first gear.
^ The engine reduces the vehicle speed.
3.5. If no engine braking is available, test for a faulty reverse band.

Coastdown Downshift Test

Power (P) Shift Mode
Set the Power/Normal switch to the Power (P) position.
1. Verify the manual selector is in the Drive (D) position.
2. Depress the OD switch.
3. Accelerate the vehicle until the transmission is in fourth gear (OD) and the TCC is applied.
4. Release the accelerator pedal and lightly apply the brake pedal, bringing the vehicle to a complete stop.
5. Verify that the TCC releases.
6. Monitor the vehicle speeds at points of downshifts.

Normal (N) Shift Mode
Set the Power/Normal switch to the Normal (N) position.
1. Verify the manual selector is in the Drive (D) position.
2. Depress the OD switch.
3. Accelerate the vehicle until the transmission is in fourth gear (OD) and the TCC is applied.
4. Release the accelerator pedal and lightly apply the brake pedal, bringing the vehicle to a complete stop.
5. Verify that the TCC releases.
6. Monitor the vehicle speeds at points of downshifts.
Verify that the gear downshifts and the TCC release occur properly as shown in the shift speed tables below. If the transmission is not within specifications, refer to Line Pressure Check Procedure for possible causes and corrections.

Manual Second (2) Gear Range Selection Test
1. Stop the vehicle.
2. Move the manual selector to the Second (2) range.
3. Slowly accelerate the vehicle and verify that the transmission upshifts from the first to the second gear.

Manual Third (D) Range
1. Slowly accelerate the vehicle to 40 km/h (25 mph).
2. Verify that the transmission does not upshift from second to third gear.
3. Verify that the TCC does NOT engage.

Manual Low Test
1. Stop the vehicle.
2. Place the manual selector in the Low (L) range.
3. Slowly accelerate the vehicle.
4. Verify that the transmission does not upshift from the first to the second gear.
5. Verify that the TCC does NOT engage.

Reverse (R) Test
1. Stop the vehicle.
2. Place the manual selector in the Reverse (R) range.
3. Slowly accelerate the vehicle.
4. Verify that the vehicle operates in a rearward direction.





Transmission Shift Speed Schedule-Power Shift Mode





Transmission Shift Speed Schedule-Normal Shift Mode

Manual Road Test Procedure
This procedure determines whether a problem lies in the electronic control system or in the transmission itself. This procedure tests the gears being used in the L, the 2, or the D ranges with the shift solenoids disconnected from the PCM.
1. Perform one of the following procedures:
^ Diagnostic System Check- Engine Controls in Engine Controls - 2.0L
^ Diagnostic System Check - Engine Controls in Engine Controls - 2.5L
2. Start the engine and warm to normal operating temperature.
3. Turn the ignition switch to LOCK.
4. Disconnect the solenoid wire harness connector from the solenoid wire harness.
5. Start the engine.
6. On a level road, move the gear selector to the Low (L) position and accelerate the vehicle to 20 km/h (13 mph). Observe that 1st gear is being used.
7. Move the gear selector to Second (2) position at 20 km/h (13 mph).
8. Accelerate to 40 km/h (25 mph). Observe that the transmission is in 3rd gear.
9. At 40 km/h (25 mph), shift the manual selector to the Drive (D) position.
10. Observe that the transmission is in 4th gear at speeds above 40 km/h (25 mph).
11. Stop the vehicle.
12. Shift to the Park (P) position and turn the ignition switch to LOCK.
13. Reconnect the solenoid wire harness connector.
14. Turn the ignition switch to ON.
15. Clear DTCs with the scan tool.
16. Compare the results of this Manual Road Test Procedure with the Road Test Procedure described previously.
^ If the transmission operates normally with the electronic control system disabled, but malfunctions with the electronic control system connected, the problem lies in the electronic control system. Refer to the appropriate DTC test.
^ If the transmission is still malfunctioning with the electronic control system disabled, the problem lies in the transmission. Refer to the Manual Road Test Diagnosis table below.





Manual Road Test Diagnosis

Stall Speed Test
Use the stall speed test in order to check the overall performance of the transmission and the engine. The test measures the maximum engine speeds in the forward and reverse ranges.

Notice: This test should always be performed at a normal operating fluid temperature of 70 to 80°C (158 to 176°F). DO NOT run engine at stall speed for more than five seconds continuously. If this precaution is not observed, engine oil and transaxle fluid temperatures may rise excessively high.

1. Inspect the transmission fluid level. The level should be between the Full Hot and the Low Hot ranges on the fluid level indicator.
2. Apply the parking brake and block the vehicle wheels.
3. Turn the ignition switch to the ON position.
4. Press the brake pedal fully.
5. Ensure that the manual selector lever is in the Park (P) position.
6. Start the engine.
7. Move the manual selector lever to the Reverse (R) position.
8. Press the accelerator pedal fully at Wide Open Throttle (WOT). While watching the tachometer, quickly read and record the engine speed (RPM) after the speed becomes constant (stall speed).
9. Release the accelerator pedal immediately after you have recorded the stall speed.
10. Return the selector lever to Park (P) position and turn the ignition switch to LOCK.

Evaluation
The stall speed should fall within 2100 - 2400 RPM for 1.6L engines, 2300 - 2600 RPM for 2.0L and 2.5L engines in all tested gear positions.





Stall Speed Test Diagnosis
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