Hummer H2. Manual — part 2423

normally-closed switch that supplies battery voltage on the TCC brake switch signal circuit to the PCM.
Applying the brake pedal opens the switch, interrupting voltage to the PCM. When the brake pedal is released,
the PCM receives a constant voltage signal. If the PCM receives a zero voltage signal at the brake switch input,
and the torque converter clutch (TCC) is engaged, the PCM de-energizes the TCC solenoid valve. The PCM
disregards the brake switch input for TCC scheduling if there is a brake switch circuit fault.

When the PCM detects a closed brake switch circuit, 12 volts, high input, during decelerations, then DTC
P0724 sets. DTC P0724 is a type C DTC.

Conditions for Running the DTC

z

No VSS assembly DTCs P0502 or P0503.

z

The ignition is ON.

z

DTC P0724 has not passed.

Conditions for Setting the DTC

The PCM detects a closed brake switch circuit, 12 volts, without changing for 2 seconds and the following
events occur eight times:

z

The vehicle speed is greater than 32 km/h (20 mph) for 6 seconds;

z

then the vehicle speed is between 8-32 km/h (5-20 mph) for 4 seconds;

z

then the vehicle speed is less than 8 km/h (5 mph).

Action Taken When the DTC Sets

z

The PCM does not illuminate the malfunction indicator lamp (MIL).

z

The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM
stores this information as Failure Records.

z

The PCM stores DTC P0724 in PCM history.

Conditions for Clearing the DTC

z

A scan tool can clear the DTC.

z

The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-
emission-related diagnostic fault occurring.

z

The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is
OFF long enough in order to power down the PCM.

Diagnostic Aids

z

Inspect the brake switch for proper mounting and operation.

z

Inspect for ABS DTCs. A faulty ABS condition may contribute to setting DTC P0724.

Test Description

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E Diagnosis (DTC P0218 To DTC P2771) - Hummer H2

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

2: This step isolates the brake switch as a source for setting the DTC.

DTC P0724

Step

Action

Value

(s)

Yes

No

1

Did you perform the Diagnostic System Check -
Engine Controls?

-

Go to Step 2

Go to Diagnostic

System Check -

Engine Controls

in Engine Controls

- 6.0L (LQ4)

2

1. Install a scan tool.

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

3. Record the DTC Failure Records.

4. Clear the DTC.

5. Select TCC Brake Switch on the scan tool.

6. Disconnect the brake switch connector from

the brake switch.

Did the TCC Brake Switch status change from
Closed to Open?

IMPORTANT:

Before clearing the DTC, use the scan tool
in order to record the Failure Records.
Using the Clear Info function erases the
Failure Records from the PCM.

CAUTION:

Refer to SIR Caution in Cautions and
Notices.

-

Go to Step 3

Go to Step 4

3

Replace the brake switch.
Refer to Stop Lamp Switch Replacement in
Lighting Systems.
Did you complete the replacement?

-

Go to Step 6

-

4

Test the signal circuit of the brake switch for a short

IMPORTANT:

The condition that affects this circuit may exist in
other connecting branches of the circuit. Refer to
Power Distribution Schematics in Wiring Systems
for complete circuit distribution.

-

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E Diagnosis (DTC P0218 To DTC P2771) - Hummer H2

DTC P0740

to power.Refer to Testing for a Short to Voltage
and extxref document="029_body-21"
filetype="sgml" extrefid="i162420">Wiring Repairs
in Wiring Systems.Did you find and correct the
condition?

Go to Step 6

Go to Step 5

5

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

-

Go to Step 6

-

6

Perform the following procedure in order to verify
the repair:

1. Select DTC.

2. Select Clear Info.

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

4. Apply and release the brake pedal.

5. Verify that the scan tool TCC Brake Switch

status indicates Open, 0 volts, for 2 seconds.

6. Select Specific DTC.

7. Enter DTC P0724.

Has the test run and passed?

-

Go to Step 7

Go to Step 2

7

With the scan tool, observe the stored information,
capture info, and DTC Info.
Does the scan tool display any DTCs that you have
not diagnosed?

-

Go to Diagnostic

Trouble Code

(DTC) List in

Engine Controls -

6.0L (LQ4)

System OK

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E Diagnosis (DTC P0218 To DTC P2771) - Hummer H2

Fig. 10: Torque Converter Clutch (TCC) Solenoid Valve Diagram
Courtesy of GENERAL MOTORS CORP.

Circuit Description

The torque converter clutch (TCC) solenoid valve is an electrical device that is used with the torque converter
clutch pulse width modulation (TCC PWM) solenoid valve in order to control TCC apply and release. The TCC
solenoid valve attaches to the transmission case assembly extending into the pump cover. The TCC solenoid
valve receives ignition voltage through the Ignition 0 voltage circuit. The powertrain control module (PCM)
controls the solenoid by providing the ground path on the TCC solenoid valve control circuit. The PCM
monitors the throttle position sensor voltage, the vehicle speed, and other inputs in order to determine when to
energize the TCC solenoid valve.

When the PCM detects a continuous open, short to ground or short to power in the TCC solenoid valve circuit,
then DTC P0740 sets. DTC P0740 is a type B DTC.

Conditions for Running the DTC

2004 Hummer H2

2004 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E Diagnosis (DTC P0218 To DTC P2771) - Hummer H2