Hummer H1 (2006+). Manual - part 109

 

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Hummer H1 (2006+). Manual - part 109

 

 

OBD-280

On-Board Diagnostics

_____________________________________________

DTC P0741 Torque Converter Clutch System Stuck Off

Circuit Description

The transmission control module (TCM) uses data from the engine speed sensor and the input speed sensor (ISS) to calculate
torque converter slip value. The TCM then compares this calculated slip value to a preset value in the TCM calibration.

DTC P0741 is a type B DTC.

Conditions for Setting the DTC

DTC P0741 sets when the TCM detects one of the following conditions:

• A TCC slip value greater than 80 RPM for 15 seconds. 

• The TCC slip speed values indicate a stuck off state. 

Action Taken When the DTC Sets 

• The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for 

Setting the DTC are met. 

• DTC P0741 will be stored in TCM history. 

• The TCM freezes shift adapts. 

• The TCM inhibits TCC engagement. 

Conditions for Clearing the DTC

A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle com-
pletes 40 warm-up cycles without failure.

Diagnostic Aids 

• Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions: 

•  A bent terminal 

• A backed-out terminal 

• A damaged terminal 

•  Poor terminal tension 

•  A chafed wire 

•  A broken wire inside the insulation 

• When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a 

change.

• You may have to drive the vehicle in order to experience a condition. 

Step

Action

Value(s)

Yes

No

    1

NOTE: Before clearing DTC(s) use the scan tool “Capture info”
to record Freeze Frame and Failure Records for reference, as data
will be lost when “Clear Info” function is used 

Was the “On-Board Diagnostic (OBD) System Check” per-
formed?

Go to step 2.

Go to OBD Sys-

tem Check.

_____________________________________________

 On-Board Diagnostics  OBD-281

5745804

    2

1.

Install the scan tool.

2.

Turn ON the ignition, with the engine OFF.

NOTE: Before clearing the DTC, use the scan tool in order to
record the Freeze Frame and Failure Records for reference. The
Clear Info function will erase the data.

3.

Record the DTC Freeze Frame and Failure Records.

4.

Clear the DTC.

5.

Using the scan tool, observe ignition voltage.

Is the voltage within the specified range?

9-18 Volts

Go to Step 3

Go to DTC 

P0562 for low 

voltage or DTC 

P0563 for high 

voltage

    3

1.

Drive the vehicle under normal operating conditions.

2.

Using the scan tool, monitor converter slip speed indicated 
when a range is attained where the TCC should be applied.

Is the slip speed value at or greater than the specified value when
the TCC should be applied?

80 RPM

Go to Step 4 

Go to Diagnos-

tic Aids

    4

This condition indicates the TCC is mechanically stuck OFF. In-
spect for the following conditions:

• Worn TCC clutch 

• Faulty torque converter clutch pulse width modulated 

(TCC PWM) solenoid 

• Debris in the TCC valve bore 

• Clogged converter relief passage 

Did you find and repair a condition?

Go to Step 5 

    5

Perform the following procedure in order to verify the repair:

1.

Clear the DTC.

2.

Start the engine.

3.

Using the scan tool, operate the vehicle under normal operat-
ing conditions.

4.

Select Specific DTC.

5.

Enter DTC P0741.

Has the test run and passed?

System OK

Go to Step 1 

Step

Action

Value(s)

Yes

No

OBD-282

On-Board Diagnostics

_____________________________________________

DTC P0742 Torque Converter Clutch System Stuck On

Circuit Description

The transmission control module (TCM) uses data from the engine speed sensor and the input speed sensor (ISS) to calculate the
torque converter slip value. The TCM then compares this calculated slip value to a preset value in the TCM calibration.

DTC P0742 is a type B DTC.

Conditions for Setting the DTC

DTC P0742 sets when the TCM detects TCC slip speed values indicating a stuck on or locked condition for 2.5 seconds.

Action Taken When the DTC Sets 

•

The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for 

Setting the DTC are met. 

•   If failure occurs before shifting is completed, the transmission will shift to NEUTRAL. If failure occurs while shifting is

being completed, the transmission will shift to NEUTRAL or 1st range while diagnostic response is active. 

•   If the shift selector is moved to NEUTRAL, the transmission will shift to NEUTRAL. 

•   If the shift selector is moved to REVERSE, the transmission will shift to NEUTRAL or REVERSE. 

•   If the shift selector is returned to DRIVE, the transmission will shift to NEUTRAL or 1st range. 

•   DTC P0742 will be stored in TCM history. 

•   The TCM inhibits TCC engagement. 

•   The TCM freezes shift adapts. 

Conditions for Clearing the DTC

A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle com-
pletes 40 warm-up cycles without failure.

Diagnostic Aids 

   Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions: 

   A bent terminal 

   A backed-out terminal 

    A damaged terminal 

   Poor terminal tension 

   A chafed wire 

   A broken wire inside the insulation 

   When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.

   You may have to drive the vehicle in order to experience a condition. 

Step

Action

Value(s)

Yes

No

    1

NOTE: Before clearing DTC(s) use the scan tool “Capture info”
to record Freeze Frame and Failure Records for reference, as data
will be lost when “Clear Info” function is used 

Was the “On-Board Diagnostic (OBD) System Check” per-
formed?

Go to step 2.

Go to OBD Sys-

tem Check.

_____________________________________________

 On-Board Diagnostics  OBD-283

5745804

    2

1.

Install the scan tool.

2.

Set the parking brake and block the wheels to prevent vehicle 
movement.

NOTE: Before clearing the DTC, use the scan tool in order to
record the Freeze Frame and Failure Records for reference. The
Clear Info function will erase the data.

3.

Record the DTC Freeze Frame and Failures Records.

4.

Clear the DTC.

5.

Start the engine.

6.

Apply the vehicle brakes and select DRIVE.

Did the engine stall?

Go to Step 3 

Go to Diagnos-

tic Aids

    3

1.

Remove the transmission oil pan. 

2.

Inspect for contaminated fluid and/or excessive material in 
the pan.

Is the fluid contaminated or excessive material found in the pan?

Go to Step 5 

Go to Step 4 

    4

This condition indicates the TCC is mechanically stuck ON. In-
spect for the following conditions:

1.

Faulty torque converter clutch pulse width modulated (TCC 
PWM) solenoid

2.

Stuck or sticking TCC valve

3.

Restricted transmission cooler lines

Did you find and repair a condition?

Go to Step 6 

    5

Remove the transmission for overhaul or replacement. 

Did you complete the repair or replacement?

Go to Step 6 

    6

Preform the following procedure in order to verify the repair:

1.

Clear the DTC.

2.

Drive the vehicle under normal operating conditions.

3.

Using the scan tool, monitor TCC slip speed. The TCC must 
engage/disengage when commanded.

4.

Select Specific DTC.

5.

Enter DTC P0742.

Has the test run and passed?

System OK

Go to Step 1 

Step

Action

Value(s)

Yes

No

 

 

 

 

 

 

 

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