Hummer H2. Manual — part 2454

z

The TCC releases

z

The transmission downshifts immediately to SECOND gear

z

The engine slows the vehicle

Manual 4-1 Downshift

1. Place the gear selector in the OVERDRIVE position.

2. Accelerate the vehicle to 48 km/h (30 mph).

3. Release the throttle while moving the gear selector to FIRST.

4. Verify the following:

z

The TCC releases.

z

The transmission downshifts immediately to FIRST gear.

z

The engine slows the vehicle.

Coasting Downshifts

1. Place the gear selector in the OVERDRIVE position.

2. Accelerate the vehicle to FOURTH gear with the TCC applied.

3. Release the throttle and lightly apply the brakes.

4. Verify the following:

z

The TCC releases

z

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 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 First

1. With the vehicle stopped, move the gear selector to FIRST.

2. Accelerate the vehicle to 32 km/h (20 mph).

3. Verify the following:

z

No upshifts occur

2004 Hummer H2

2004 TRANSMISSION Automatic Transaxle - 4L60-E/4L65-E (Troubleshooting)

z

The TCC does not apply

z

There is no noticeable slip, noise, or vibration

Manual Second

1. With the vehicle stopped, move the gear selector to SECOND.

2. Accelerate the vehicle to 57 km/h (35 mph).

3. Verify the following:

z

The 1-2 shift occurs

z

The 2-3 shift does not occur

z

There is no noticeable slip, noise or vibration

Manual Third

1. With the vehicle stopped, move the gear selector to THIRD.

2. Accelerate the vehicle to 64 km/h (40 mph).

3. Verify the following:

z

The 1-2 shift occurs

z

The 2-3 shift occurs

z

There is no noticeable slip, noise or vibration

TORQUE CONVERTER DIAGNOSIS PROCEDURE

The Torque Converter Clutch (TCC) is applied by fluid pressure, which is controlled by a PWM solenoid valve.
This solenoid valve is located inside of the automatic transmission assembly. The solenoid valve is controlled
through a combination of computer controlled switches and sensors.

Torque Converter Stator

The torque converter stator roller clutch can have two different malfunctions.

z

The stator assembly freewheels in both directions.

z

The stator assembly remains locked up at all times.

Poor Acceleration at Low Speed

If the stator is freewheeling at all times, the vehicle tends to have poor acceleration from a standstill. At speeds
above 50-55 km/h (30-35 mph), the vehicle may act normally. For poor acceleration, you should first determine
that the exhaust system is not blocked, and the transmission is in First gear when starting out.

If the engine freely accelerates to high RPM in NEUTRAL, you can assume that the engine and the exhaust
system are normal. Check for poor performance in DRIVE and REVERSE to help determine if the stator is
freewheeling at all times.

2004 Hummer H2

2004 TRANSMISSION Automatic Transaxle - 4L60-E/4L65-E (Troubleshooting)

Poor Acceleration at High Speed

If the stator is locked up at all times, performance is normal when accelerating from a standstill. Engine RPM
and vehicle speed are limited or restricted at high speeds. Visual examination of the converter may reveal a blue
color from overheating.

If the converter has been removed, you can check the stator roller clutch by inserting a finger into the splined
inner race of the roller clutch and trying to turn the race in both directions. You should be able to freely turn the
inner race clockwise, but you should have difficulty in moving the inner race counterclockwise or you may be
unable to move the race at all.

Noise

You may notice a torque converter whine when the vehicle is stopped and the transmission is in DRIVE or
REVERSE. This noise will increase as you increase the engine RPM. The noise will stop when the vehicle is
moving or when you apply the torque converter clutch, because both halves of the converter are turning at the
same speed.

Perform a stall test to make sure the noise is actually coming from the converter:

1. Place your foot on the brake.

2. Put the gear selector in DRIVE.

3. Depress the accelerator to approximately 1,200 RPM for no more than six seconds.

A torque converter noise will increase under this load.

Torque Converter Clutch Shudder

The key to diagnosing Torque Converter Clutch (TCC) shudder is to note when it happens and under what
conditions.

TCC shudder which is caused by the transmission should only occur during the apply or the release of the
converter clutch. Shudder should never occur after the TCC plate is fully applied.

If Shudder Occurs During TCC Apply or Release

If the shudder occurs while the TCC is applying, the problem can be within the transmission or the torque
converter. Something is causing one of the following conditions to occur:

IMPORTANT: Do not confuse this noise with pump whine noise, which is usually noticeable

in PARK, NEUTRAL and all other gear ranges. Pump whine will vary with line
pressure.

NOTE:

You may damage the transmission if you depress the accelerator for more
than 6 seconds.

2004 Hummer H2

2004 TRANSMISSION Automatic Transaxle - 4L60-E/4L65-E (Troubleshooting)

z

Something is not allowing the clutch to become fully engaged.

z

Something is not allowing the clutch to release.

z

The clutch is releasing and applying at the same time.

One of the following conditions may be causing the problem to occur:

z

Leaking turbine shaft seals

z

A restricted release orifice

z

A distorted clutch or housing surface due to long converter bolts

z

Defective friction material on the TCC plate

If Shudder Occurs After TCC has Applied

If shudder occurs after the TCC has applied, most of the time there is nothing wrong with the transmission.

The TCC is not likely to slip after the TCC has been applied. Engine problems may go unnoticed under light
throttle and load, but they become noticeable after the TCC apply when going up a hill or accelerating. This is
due to the mechanical coupling between the engine and the transmission.

Once TCC is applied, there is no torque converter (fluid coupling) assistance. Engine or driveline vibrations
could be unnoticeable before TCC engagement.

Inspect the following components in order to avoid misdiagnosis of TCC shudder. An inspection will also avoid
the unnecessary disassembly of a transmission or the unnecessary replacement of a torque converter.

z

Spark plugs - Inspect for cracks, high resistance or a broken insulator.

z

Plug wires - Look in each end. If there is red dust (ozone) or a black substance (carbon) present, then the
wires are bad. Also look for a white discoloration of the wire. This indicates arcing during hard
acceleration.

z

Coil - Look for a black discoloration on the bottom of the coil. This indicates arcing while the engine is
misfiring.

z

Fuel injector - The filter may be plugged.

z

Vacuum leak - The engine will not get a correct amount of fuel. The mixture may run rich or lean
depending on where the leak occurs.

z

EGR valve - The valve may let in too much or too little unburnable exhaust gas and could cause the
engine to run rich or lean.

z

MAP/MAF sensor - Like a vacuum leak, the engine will not get the correct amount of fuel for proper
engine operation.

z

Carbon on the intake valves - Carbon restricts the proper flow of air/fuel mixture into the cylinders.

z

Flat cam - Valves do not open enough to let the proper fuel/air mixture into the cylinders.

z

Oxygen sensor - This sensor may command the engine too rich or too lean for too long.

z

Fuel pressure - This may be too low.

2004 Hummer H2

2004 TRANSMISSION Automatic Transaxle - 4L60-E/4L65-E (Troubleshooting)