Hummer H1 (2006+). Manual — part 115

OBD-304

On-Board Diagnostics

_____________________________________________

Action Taken When the DTC Sets

• The TCM illuminates the malfunction indicator lamp (MIL).

• When in a forward range, the transmission will shift to another forward 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 a forward range and the transmission is compromised by over speeding or direction

change, the transmission will lock in NEUTRAL.

• DTC P0768 will be stored in TCM history.

• The TCM freezes shift adapts.

• The TCM inhibits torque converter clutch (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.

• Solenoids are sensitive to battery voltage spikes and poor ground connections. This condition may not be indicated with

your scan tool, or with a DVOM.

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.

2

1.

Install the scan tool.

2.

Start the engine.

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, measure 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

_____________________________________________

On-Board Diagnostics OBD-305

5745804

3

1.

Turn the ignition OFF.

2.

Disconnect C79 at the TCM.

3.

Install the J 39700 breakout box and the J 43799 breakout
box adapter.

4.

Using a DVOM, measure voltage between connector C79
terminal 27 and terminal 31.

5.

Turn ON the ignition, with the engine OFF.

6.

Using the scan tool, command shift solenoid D to ON.

Is the voltage within the specified value when shift solenoid D is
commanded ON?

B+

Go to Step 4

Go to Step 10

4

1.

Turn the ignition OFF.

2.

Using a DVOM, measure the resistance between connector
C79 terminal 27 and terminal 31.

Is the resistance reading within the specified value?

22.0 ohms

[commat]

20°C

(68°F)

Go to Diagnos-

tic Aids

Go to Step 5

5

1.

Turn the ignition OFF.

2.

Connect C79 at the TCM.

3.

Disconnect the wiring harness from the transmission 20-way
connector C34.

4.

Using a DVOM, measure the resistance on the transmission
side of the 20-way connector between terminals B and C.

Is resistance within the specified value?

22.0 ohms

[commat]

20°C

(68°F)

Go to Step 6

Go to Step 7

6

Inspect the harness Between C34 and C79 on circuits 782 (TN)
and 778 (DB) for an open or short to ground on.

Did you find and correct a condition?

Go to Step 11

7

1.

Remove the oil pan. Refer to Transmission Oil Pan Replace-
ment.

2.

Remove the AT internal wiring harness at shift solenoid D
connector.

3.

Using a DVOM, measure the resistance of D solenoid.

Is the solenoid resistance within the specified value?

22.0 ohms

[commat]

20°C

(68°F)

Go to Step 8

Go to Step 9

8

Replace the AT internal wiring harness.

Did you complete the replacement?

Go to Step 11

9

Replace shift solenoid D.

Did you complete the replacement?

Go to Step 11

10

NOTE: In most cases, the TCM is not at fault. Investigate thor-
oughly before replacing the TCM.

Replace the faulty TCM.

Did you complete the replacement?

Go to Step 11

11

Perform the following procedure in order to verify the repair:

1.

Clear the DTC.

2.

Drive the vehicle under normal operating conditions.

3.

Select Specific DTC.

4.

Enter DTC P0768.

Has the test run and passed?

System OK

Go to Step 1

Step

Action

Value(s)

Yes

No

OBD-306

On-Board Diagnostics

_____________________________________________

DTC P0773 Shift Solenoid E Circuit Electrical (Figure OBD-80)

Figure OBD-80: Shift Solenoid E Circuit

Circuit Description

Shift E solenoid is a normally closed (N/C) solenoid that provides control main pressure to stroke the E shift valve. The transmis-
sion control module (TCM) determines the proper solenoid command logic to move the E shift valve to attain a particular range.

Since the valve state, stroked or unstroked, is critical to providing the correct transmission range, the shift valve has a pressure
switch, located in the pressure switch manifold, to provide feedback to the TCM as to the position of the valve.

DTC P0773 is a type A DTC.

Conditions for Setting the DTC

DTC P0773 sets when the TCM detects any one of the following conditions for greater than 100 milliseconds:

• An open circuit or a short to ground is detected when E solenoid is commanded OFF.

• A short to power is detected when E solenoid is commanded ON.

_____________________________________________

On-Board Diagnostics OBD-307

5745804

Action Taken When the DTC Sets

• The TCM illuminates the malfunction indicator lamp (MIL).

• When in a forward range, the transmission will shift to another forward 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 a forward range and the transmission is compromised by over speeding or direction

change, the transmission will lock in NEUTRAL.

• DTC P0773 will be stored in TCM history.

• The TCM freezes shift adapts.

• The TCM inhibits torque converter clutch (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.

Solenoids are sensitive to battery voltage spikes and poor ground connections. This condition may not be indicated with your

scan tool, or with a DVOM.

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnos-

tic System

Check

2

1.

Install the scan tool.

2.

Start the engine.

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, measure 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