Hummer H2. Manual — part 2451

TOW/HAUL SWITCH/INDICATOR ALWAYS ON OR INOPERATIVE

11

indicate proper voltage for an open.
Refer to Testing for Continuity and Wiring Repairs
in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 17

Go to

Step

15

12

Test the affected signal circuits of the TR switch for a
shorted together condition.
Refer to Circuit Testing and Wiring Repairs in
Wiring Systems.
Did you find and correct the condition?

-

Go to Step 17

Go to

Step

15

13

Test the ground circuit of the TR switch for an open.
Refer to Testing for Continuity and Wiring Repairs
in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 17

Go to

Step

14

14

Replace the TR switch, this switch is part of the
park/neutral position switch.
Refer to Park/Neutral Position Switch Replacement .
Did you complete the replacement?

-

Go to Step 17

-

15

Replace the PCM.
Refer to Powertrain Control Module (PCM)
Replacement in Engine Controls - 6.0L (LQ4).
Did you complete the replacement?

-

Go to Step 17

-

16

Replace the IPC.
Refer to Instrument Panel Cluster (IPC)
Replacement in Instrument Panel, Gauges and Console.
Did you complete the replacement?

-

Go to Step 17

Go to

Step 2

17

1. Turn ON the ignition, with the engine OFF.

2. With the scan tool, observe the TR Sw. display

while selecting each transmission range: P, R, N,
D4, D3, D2 and D1.

Does each selected transmission range match the scan
tool TR Sw. display?

-

System OK

Go to

Step 2

2004 Hummer H2

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

Fig. 2: Tow/Haul Mode Diagram
Courtesy of GENERAL MOTORS CORP.

Circuit Description

Tow/haul mode enables the operator to achieve enhanced shift performance when towing or hauling a load.
When tow/haul mode is selected, the tow/haul switch input signal to the body control module (BCM) is
momentarily toggled to zero volts. This signals the powertrain control module (PCM) to extend the length of
time between upshifts and increase transmission line pressure. Cycling the tow/haul switch again disables
tow/haul mode and returns the transmission to a normal shift pattern.

Diagnostic Aids

If the electrical circuit tests are OK and the tow/haul shift pattern is not occurring, there may be a

2004 Hummer H2

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

mechanical/hydraulic condition that prevents tow/haul operation. Refer to Symptoms - Automatic
Transmission .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2: This step tests for a faulty tow/haul switch.

3: This step tests for voltage input from the BCM to the tow/haul switch.

6: This step tests for voltage through the body wiring harness junction block.

7: This step tests for ground integrity at the splice pack.

Tow/Haul Switch/Indicator Always On or Inoperative

Step

Action

Value

(s)

Yes

No

1

1. Install a scan tool.

2. Turn ON the ignition, with the engine

OFF.

3. Cycle the tow/haul switch while

observing Tow/Haul Mode on the
scan tool.

Does the scan tool display Active when the
switch is first pressed, and then Inactive
when the switch is pressed again?

-

Go to Intermittent

Conditions in Engine

Controls - 6.0L (LQ4)

Go to Step 2

2

1. Disconnect the I/P wiring harness

connector from the tow/haul switch.

2. Install a fused jumper wire from

terminal A to terminal B of the I/P
wiring harness connector.

Does the scan tool Tow/Haul Mode indicate
a status change?

-

Go to Step 7

Go to Step 3

3

Using the DMM and the J 35616 GM
Terminal Test Kit, measure the voltage at
terminal A of the I/P wiring harness
connector.
Is ignition voltage measured?

-

Go to Step 6

Go to Step 4

4

Using the DMM and the J 35616 , measure
the voltage at terminal C3-B11 of the body
control module (BCM).
Is ignition voltage measured?

-

Go to Step 5

Go to Step 8

Test the signal circuit of the tow/haul
switch for an open or shorted condition.

2004 Hummer H2

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

TRANSMISSION FLUID CHECKING PROCEDURE

1. Start the engine and operate the vehicle for 15 minutes or until the transmission fluid reaches an operating

temperature of 82-93°C (180-200°F).

2. Park the vehicle on a level surface.

3. With your foot on the brake, move the shift lever through each gear range. Pause for about 3 seconds in

each range, ending in PARK.

4. Apply the parking brake and let the engine idle for 3 minutes.

5. Remove the transmission fluid level indicator. Wipe the indicator clean. Insert the indicator. Give the

indicator a full twist in order to close.

6. Wait 3 seconds and remove the indicator.

7. Read both sides of the indicator. The fluid must be within the hot cross-hatched area using the lowest

level reading.

Transmission Fluid Checking Procedure

5

Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 9

Go to Intermittent

Conditions in Engine

Controls - 6.0L (LQ4)

6

Test the ground circuit of the tow/haul
switch for an open or shorted condition
between terminal B of the I/P wiring
harness connector and ground (G203).
Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.
Did you find and correct the condition?

-

Go to Step 9

Go to Intermittent

Conditions in Engine

Controls - 6.0L (LQ4)

7

Replace the tow/haul switch.
Did you complete the replacement?

-

Go to Step 9

-

8

Test the BCM for proper operation.
Refer to Diagnostic Starting Point - Body
Control System in Body Control System.
Did you find and correct the condition?

-

Go to Step 9

-

9

After the repair is complete, observe
Tow/Haul Mode on the scan tool display,
while cycling the tow/haul switch.
Does the scan tool display Active when the
switch is first pressed, and then Inactive
when the switch is pressed again?

-

System OK

Go to Step 1

Step

Action

Yes

No

1

Check the fluid color.
Is the fluid red in color?

Go to

Step 5

Go to

Step 2

2

Is the fluid a non-transparent pink in color?

Go to

Step 14

Go to

Step 3

IMPORTANT:

2004 Hummer H2

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