Hummer H2. Manual - part 2432

15 Test the Ignition 0 voltage circuit of the 1-2 SS valve

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

other connecting branches of the circuit. Refer to
Power Distribution Schematics in Wiring Systems
for complete circuit distribution.

Go to Step 21

Test the control circuit of the 1-2 SS valve for a short
to ground between the PCM connector C2 and the AT
inline 20-way connector.
Refer to Testing for Short to Ground 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 21

Go to Step 20

Test the control circuit of the 1-2 SS valve for an
open or short to power between the PCM connector
C2 and the AT inline 20-way connector.
Refer to Circuit Testing 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 21

Go to Step 20

Replace the AT wiring harness assembly.
Refer to Valve Body and Pressure Switch
Replacement .
Did you complete the replacement?

Go to Step 21

Replace the 1-2 SS valve.
Refer to Valve Body and Pressure Switch
Replacement .
Did you complete the replacement?

Go to Step 21

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

Go to Step 21

Perform the following procedure in order to verify the
repair:

1. Select DTC.

2. Select Clear Info.

3. Drive the vehicle in D4 and ensure that the

following conditions are met:

The PCM commands the 1-2 SS valve

2004 Hummer H2

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

DTC P0756

Fig. 17: 1-2 Shift Solenoid (SS) & 2-3 Shift Solenoid (SS) Valve Fluid Diagram
Courtesy of GENERAL MOTORS CORP.

Circuit Description

ON and the voltage feedback drops to
zero.

The PCM commands the 1-2 SS valve
OFF and the voltage feedback increases
to B+.

All conditions are met for 5 seconds.

4. Select Specific DTC.

5. Enter DTC P0753.

Has the test run and passed?

Go to Step 22

Go to Step 2

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

The 2-3 shift solenoid (SS) valve controls the fluid flow acting on the 2-3 shift valves. The 2-3 SS valve is a
normally-open exhaust valve that is used with the 1-2 SS valve, in order to allow four different shifting
combinations.

When the PCM detects a 4-3-3-4 shift pattern, then DTC P0756 sets. DTC P0756 is a type A DTC.

Conditions for Running the DTC

No TP sensor DTCs P0122 or P0123.

No VSS assembly DTCs P0502 or P0503.

No TCC solenoid valve DTC P0740.

No TCC stuck ON DTC P0742.

No 1-2 SS valve DTC P0753.

No 2-3 SS valve DTC P0758.

No 3-2 SS valve assembly DTC P0785.

No TFP manual valve position switch DTC P1810.

No TCC PWM solenoid valve DTC P2761.

The engine speed is greater than 450 RPM for 5 seconds.

The engine is not in fuel cutoff.

The gear range is D4.

The TP angle is greater than 10 percent.

The transmission fluid temperature is 20-130°C (68-266°F).

The engine torque is 36-295 N.m (50-400 lb ft).

The transmission output speed is 150 RPM or greater.

The transfer case ratio in 4WD low is 0.9-1.2.

The transfer case ratio in 4WD high is 2.6-2.85.

Conditions for Setting the DTC

DTC P0756 sets if both of the following conditions occur:

Condition 1

The PCM commands first gear for 2 seconds.

The estimated gear ratio is 0 to 1.4.

All conditions are met for 1 second.

Condition 2

The PCM commands second gear for 1 second.

The estimated gear ratio is 0.9 to 1.2.

2004 Hummer H2

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

All conditions are met for 2 seconds.

Action Taken When the DTC Sets

The PCM illuminates the malfunction indicator lamp (MIL).

The PCM commands third gear only.

The PCM commands maximum line pressure.

The PCM inhibits TCC engagement.

The PCM freezes transmission adapt functions.

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

The PCM stores DTC P0756 in PCM history.

Conditions for Clearing the MIL/DTC

The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and
passes.

A scan tool can clear the MIL/DTC.

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

The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power
down the PCM.

Diagnostic Aids

Verify that the transmission meets the specifications in the Shift Speed table.

Other internal transmission failures may cause more than one shift to occur.

Refer to the Shift Solenoid Valve State and Gear Ratio table.

Test Description

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

2: This step tests that the PCM commanded all shifts, that all shift solenoid valves responded correctly,
but that all the shifts did not occur.

DTC P0756

Step

Action

Value

(s)

Yes

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)

2004 Hummer H2

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

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