Hummer H1 (2006+). Manual - part 193

5-12

Transmission/Transfer Case

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2.

Make sure that the engine is at idle.

3.

With the vehicle in the park position (P).

4.

Apply the park brake and make sure it is holding properly.

5.

Run the engine for at least one minute.

6.

Shift to drive (D), then to neutral (N), then shift to reverse (R) to fill the hydraulic system and finally shift back to the park
position (P).

7.

With the vehicle in park and the engine running, remove the transmission dipstick.

8.

Wipe the dipstick clean, insert the dipstick fully and remove.

9.

Check the fluid reading, repeat step 8 to verify the reading.

10. Only fill to the “Cold” reading on the dipstick.

11. Perform a hot test as soon as the transmission temperature reaches 160º F-200º F (71ºC-93ºC).

TRANSMISSION FLUID CHECKING PROCEDURE (HOT)

1.

Operate the transmission in drive (D) range until normal operating temperature is reached 160º F-200º F (71ºC-93ºC).

2.

Bring the vehicle to a complete stop on a level surface using the service brakes.

3.

Make sure that the engine is at idle.

4.

With the vehicle in the park (P) position.

5.

Apply the park brake and make sure it is holding properly.

6.

With the vehicle in park and the engine running, remove the transmission dipstick.

7.

Wipe the dipstick clean, insert the dipstick fully and remove.

8.

Check the fluid reading, repeat step 7 to verify the reading.

9.

If the fluid level is not within the “HOT” range, add or drain as necessary to bring the fluid to the proper level.

ROAD TEST PROCEDURE 

NOTE: The Road Test Procedure should be performed only as part of the Functional Test Procedure. 

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 Detent Downshifts   

• Full Throttle Detent Downshifts 

• Manual Downshifts 

• Coasting Downshifts 

• Manual Range Selection 

• REVERSE 

• Manual FIRST 

• Manual SECOND 

• Manual THIRD 

NOTE: Complete the test in the sequence given. Incomplete testing cannot guarantee an accurate evaluation. 

Before the road test, ensure the following conditions are met:   

• The engine is performing properly

• Transmission fluid level is correct 

• Tire pressure is correct

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During the road test:   

• Perform the test only when traffic conditions permit 

• Operate the vehicle in a controlled, safe manner

• Observe all traffic regulations 

• Take along qualified help in order to View the scan tool data while conducting this test 

• Observe any unusual sounds or smells 

• After the road test, inspect the following conditions: 

• Transmission fluid level 

• Diagnostic trouble codes (DTCs) that may have set during the testing and Refer to the applicable DTC 

• Scan tool data for any abnormal readings or data 

Electrical Function Check 

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

1.

Install the scan tool. 

2.

Ensure the shift 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: 

• Engine speed 

• Transmission input speed, turbine speed 

• Transmission output speed   

• Vehicle speed 

• C, D, E and REVERSE pressure switch states 

• Transmission range, engine list 

• 4WD  low 

• Commanded range, current range 

• A and B solenoid reference current 

• A and B solenoid actual current 

• A and B solenoid duty cycle 

• Brake  switch     

• Engine coolant temperature   

• Transmission fluid temperature 

• Throttle angle   

• Ignition voltage   

• C shift solenoid ON/OFF 

• D shift solenoid ON/OFF 

• E shift solenoid ON/OFF 

• TCC solenoid duty cycle 

• TCC slip speed 

5.

Monitor the brake switch signal while depressing and releasing the brake pedal. The scan tool should display the following:   

• Closed when the brake pedal is released   

• Open when the brake pedal is depressed 

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Transmission/Transfer Case

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6.

Check the garage shifts. 

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

• Move the shift selector through the following ranges: 

• PARK to REVERSE 

• REVERSE to NEUTRAL 

• NEUTRAL to DRIVE 

• Pause 2 to 3 seconds in each selector position

• Verify the range engagements are immediate and not harsh

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

• High idle speed Compare engine idle speed to desired idle speed 

• Commanded low A or B solenoid current Compare A and B solenoid reference current to A and B solenoid actual current 

• A default condition caused by certain DTCs that result in maximum full throttle shift points 

• Shift is not fully adapted 

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 

• Cold transmission fluid Inspect for low transmission fluid temperature

7.

Monitor the transmission range on the scan tool engine list. Apply the brake pedal and ensure the parking brake is set while
performing the following: 

• Move the shift selector through all ranges

• Pause 2 to 3 seconds in each range

• Return the shift selector to PARK 

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

8.

Inspect the throttle angle input. Apply the brake pedal and ensure the parking brake is set. 

• Ensure the shift selector is in PARK. 

• Monitor the throttle angle while increasing and decreasing the engine speed with the throttle pedal. The scan tool throttle an-

gle should increase and decrease with the engine speed. 

If any of the above checks do not perform properly, record the result for reference after the completion of the Road Test Procedure. 

Upshift Control and Torque Converter Clutch (TCC) Apply 

The transmission control module (TCM) calculates the upshift points based on the throttle angle and the engine, turbine and output
speed. When the TCM determines that conditions are met for a shift to occur, the TCM commands the shift, and controls A and B
solenoid current to proper control clutch pressures during the shift. 

Perform the following steps: 

1.

Choose a throttle position of 10 percent, 25 percent or 50 percent. All throttle angles shown should be tested to cover the nor-
mal driving range. 

2.

Monitor the following scan tool parameters: 

• Throttle angle 

• Vehicle speed   

• Engine speed 

• Output shaft speed   

• Commanded range 

• Slip speed 

• Solenoid states 

3.

Place the shift selector in drive (D). 

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4.

Using the chosen throttle angle, accelerate the vehicle. Hold the throttle steady. 

5.

As the transmission upshifts, note the vehicle speed when the shift occurs for each range change. There should be a noticeable
shift feel or engine speed change within 1 to 2 seconds of the commanded range change. 

6.

Shift speeds may vary slightly due to 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 vibration. 

7.

Repeat steps 1-6 to complete all throttle angles. 

NOTE: The TCC will not engage until the engine is in closed loop operation. The vehicle must be in a near cruise condition, not
accelerating or coasting, and on a level road surface. 

8.

Inspect for TCC apply in SECOND, THIRD, FOURTH and FIFTH range. 

• 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 inspect for DTCs. 

• Lightly tap and release the brake pedal. The TCC will release on most applications.

Part Throttle Detent Downshift 

1.

Place the shift selector in drive (D). 

2.

Accelerate the vehicle to a speed just above the FOURTH to FIFTH shift point, using less than 50 percent throttle. 

3.

Quickly increase throttle angle to greater than 63 percent. 

4.

Verify the following conditions: 

• The TCC releases. 

• The transmission downshifts immediately to FOURTH range. 

Manual Downshifts 

Manual 5-3 Downshift 

1.

Place the shift selector in drive (D). 

2.

Accelerate the vehicle to obtain FIFTH range. 

3.

Release the throttle while moving the shift selector to THIRD. 

4.

Verify the following conditions: 

• The TCC releases. 

• The transmission downshifts immediately to FOURTH range and then to THIRD range. 

• The engine slows the vehicle. 

Manual 5-2 Downshift 

1.

Place the shift selector in drive (D). 

2.

Accelerate the vehicle to obtain FIFTH range. 

3.

Release the throttle while moving the shift selector to SECOND. 

4.

Verify the following conditions: 

• The TCC releases. 

• The transmission downshifts immediately to FOURTH range, then to THIRD, then to SECOND. 

• The engine slows the vehicle. 

Manual 2-1 Downshift 

1.

Place the shift selector in drive (D). 

2.

Accelerate the vehicle until the 1-2 shift occurs. 

3.

Go to 5 mph (8 km/h) above the 1-2 shift point.