Hummer H2. Manual - part 2405

1. Replace the transmission oil cooler.  

2. Connect the supply and waste hoses to the cooler lines in the normal flow direction. Perform the 

Flow Test.  

3. Perform the Code Recording Procedure.  

Code Recording Procedure 

Fig. 21: Turning Main Function Switch To CODE Position 
Courtesy of GENERAL MOTORS CORP. 

1. Turn the main function switch to the CODE position. 

IMPORTANT:

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If power is interrupted prior to the recording of the 7-character code, 
the code will be lost and the flow rate test will need to be repeated.  

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The flow test must run for a minimum of 8-10 seconds and be above 
0.5 gpm for a code to be generated.  

 

2004 Hummer H2 

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

  

2. Record TESTED flow rate, temperature, cycle and seven-character flow code information on the repair 

order.  

Clean-Up 

Fig. 22: Turning Main Function Switch To IDLE Position 
Courtesy of GENERAL MOTORS CORP. 

1. Turn the main function switch to the IDLE position and allow the supply vessel pressure to dissipate. 

 

2004 Hummer H2 

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

  

2. Turn the main power switch to the OFF position. 

3. Disconnect the supply and waste hoses and the 12-volt power source from the vehicle. 

Fig. 23: Connecting A Shop Air Supply Hose To Quick-Disconnect 
Courtesy of GENERAL MOTORS CORP. 

4. Disconnect the air supply hose from J 45096 .  

5. Dispose of the waste ATF in accordance with all applicable federal, state, and local requirements.  

AUTOMATIC TRANSMISSION OIL COOLER FLUSHING AND FLOW TEST (J 35944-A) 

GM studies indicate that plugged or restricted transmission oil coolers and pipes cause insufficient transmission 

IMPORTANT: A small amount of water may drain from the bottom of the unit when the 

air supply is disconnected. This is a normal operation of the built-in water 
separator.

 

2004 Hummer H2 

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

  

lubrication and elevated operating temperatures which can lead to premature transmission wear-out. Many 
repeat repair cases could have been prevented by following published procedures for transmission oil cooler 
flushing and flow checking. This procedure includes flow checking and flushing the auxiliary transmission oil 
cooler, if equipped. 

Only GM Goodwrench DEXRON(R)III automatic transmission fluid should be used when doing a repair on a 
GM transmission. 

Time allowance for performing the cooler flow checking and flushing procedure has been included in the 
appropriate labor time guide operations since the 1987 model year. The service procedure steps for oil cooler 
flushing are as follows: 

Cooler Flow Check and Flushing Steps 

1. Tools Required  

2. Preparation  

3. Back Flush  

4. Forward Flush  

5. Flow Check  

6. Clean-up  

Tools Required 

IMPORTANT: Use the J 35944-A or equivalent to flush the transmission oil cooler and the oil 

cooler pipes whenever the transaxle is removed for the following repairs: 

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Torque converter  

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Oil pump  

z

Oil pump drive shaft  

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Drive sprocket support  

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Transaxle overhaul complete  

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Transaxle assembly replacement  

IMPORTANT: Use the J 35944-A or equivalent to flush the transmission oil cooler and the oil 

cooler pipes whenever the transmission is removed for the following repairs: 

z

Torque converter  

z

Oil pump  

z

Turbine shaft  

z

Transmission overhaul complete  

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Transmission assembly replacement  

 

2004 Hummer H2 

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