Content .. 73 74 75 76 ..

Hummer H1 (2002+). Manual - part 75

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Transmission/Transfer Case 5-99

05745159

DTC P0756 2-3 Shift Solenoid Valve Performance

Step

Action

Value

Yes

Connect scan tool.

Turn the ignition switch on.

Record “Freeze Frame” and “Failure Records.”

Start engine, apply brake pedal and shift into D1, D2, D3,
D4, N, R, and P.

Does each selected transmission range match “TR Switch” on
the scan tool?

—

Go to Step 2

Go to Pres-

sure Switch

Assembly

Resistance

Check

Raise vehicle on twist that allows wheels to turn freely.

Start engine and shift into D4 range. Use scan tool to
command 1st, 2nd, 3rd, and 4th gears while increasing
engine speed.

Was 1st gear commanded and not achieved, or 4th gear com-
manded and other than 4th gear occurred? (Road testing the
vehicle may be necessary).

—

Go to Step 3

Go to Diag-

nostic Aids

Check the shift solenoid/hydraulic circuit for:

• An internal malfunction.

• Damaged seals on shift solenoids.

Was a problem found and corrected?

—

Go to Step 4

—

After repair is complete, use scan tool to select “DTC,”
then Clear Info” function.

Select “Specific DTC” and enter DTC “P0756.”

Operate the vehicle under the following conditions (only
if traffic and road conditions permit):

• PCM must see the proper gear ratio for each com-

manded gear for greater than one second in D1, D2,
D3, and D4. Hold the throttle at 25% and accelerate to
55 mph.

—

Repair veri-

fied, exist

DTC table.

5-100

Transmission/Transfer Case

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DTC P0758, 2-3 Shift Solenoid Electrical

Circuit Description

The 2-3 shift solenoid controls fluid acting on the 2-3 shift valves.
The solenoid is a normally open valve. It is used with the 1-2 shift
solenoid to provide four different shift combinations. The solenoid
is attached to the control valve body. Ignition voltage is supplied
directly to the 2-3 shift solenoid. The PCM controls the solenoid
by providing a ground path through circuit 315.

This DTC detects a continuous open or short to ground in the 2-3
shift solenoid circuit or 2-3 shift solenoid.

Conditions for Running the DTC

• The engine is running greater then 475 RPM for greater

than 7 seconds and system voltage is normal.

Conditions For Setting DTC

The PCM detects either of the following fail conditions for 4.3
of 5 seconds.

• The PCM commands the solenoid “on” and voltage re-

mains high (B+).

• The PCM commands the solenoid off and voltage re-

mains low (zero volts).

Action Taken When DTC Sets

• Immediate shift to second gear.

• The PCM commands maximum line pressure.

• Freeze 1-2 shift adapts from being updated.

• Inhibit converter clutch engagement.

• The PCM illuminates warning lamp.

Conditions For Clearing DTC

• For California and Federal vehicles the PCM turns the

warning lamp off after three consecutive ignition cycles
without a failure reported.

• The DTC can be cleared using the scan tool. The DTC

will be cleared when the vehicle has achieved 40 warm-
up cycles without a failure reported.

• The PCM will cancel the DTC default actions when the

fault no longer exists and the ignition is cycled “off”
long enough to power down the PCM.

FUSE 2A

10A

EXTERIOR

C33-F

351 PK

C34

C32-G

C32-F

C32-E

C32-D

C32-C

C32-J

C32-H

C34-E

C27-C15

C27-C7

C28-C5

C28-C6

C28-C4

C29-B12

C27-C9

265 LB

264 RD

924 TN

315 YL

237 LG

359 BK

923 BR

PRESSURE

CONTROL

SOLENOID

(PCS)

TORQUE

CONVERTER

CLUTCH

SOLENOID

(TCC)

1-2 SHIFT
SOLENOID
(1-2)

2-3 SHIFT
SOLENOID
(2-3)

TRANSMISSION

FLUID

TEMPERATURE

SENSOR

(TFT)

PCS

LOW

PCS

HIGH

TCC PWM

SOLENOID

CONTROL

2-3 SS

CONTROL

1-2 SS

CONTROL

SENSOR

GROUND

TFT

SENSOR

SIGNAL

POWERTRAIN

CONTROL

MODULE

(PCM)

HOT IN RUN
AND START

9 - S 1 2 - 0 6 7

3-1-01

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Transmission/Transfer Case 5-101

05745159

Diagnostic Aids

• Inspect the wiring for poor electrical connections at the

PCM and at the transmission 20-way connector. Look
for possible bent, backed out, deformed or damaged ter-
minals. Check for weak terminal tension as well. Also
check for a chafed wire that could short to bare metal or
other wiring. Inspect for a broken wire inside the insula-
tion.

• When diagnosing for a possible intermittent short or

open condition, move or massage the wiring harness
while observing test equipment for a change.

• If any engine DTCs or TP Sensor codes are present di-

agnose and clear these DTCs first. Then check to see if
the transmission DTCs have reset.

Test Description

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

3. This test checks the function of the 2-3 shift solenoid

and the transmission internal wiring harness.

5. This test checks for power to the 2-3 shift solenoid

from the ignition through the fuse.

14. This test measures the resistance of the component.

4L80-E CHART

Gear

1-2 Shift
Solenoid

2-3 Shift
Solenoid

OFF

DTC P0758 2-3 Shift Solenoid B Electrical

Step

Action

Value

Yes

Connect scan tool.

Turn ignition switch to the “Run” position.

NOTE: Important:

Before clearing DTC(s), use the

scan tool to record “Freeze Frame” and “Failure
Records” for reference, as data will be lost when the
“Clear Info” function is used.

Record the DTC “Freeze Frame” and “Failure
Records.”

Were DTCs P0753, P0758, and P1860 set?

—

Go to step 2.

Go to step 3.

Inspect fuse 2A of the exterior fuse box.

If fuse was blown, inspect/repair circuit wiring
solenoid, and internal wiring harness for short to
ground.

Was a problem found and corrected?

—

Go to step 15.

Go to step 4.

Using the “transmission out put control function” on
the scan tool, actuate the 2-3 shift solenoid valve “ON”
and “OFF” three times. The solenoid should click when
being actuated.
Does the solenoid click when actuated?

—

Go to Diagos-

tic Aids.

Go to step 4.

3-1-01

5-102

Transmission/Transfer Case

___________________________________________

Turn ignition “Off”.

Disconnect transmission 20-way connector (addi-
tional DTCs will set).

Connect 05743837 Jumper Harness to engine har-
ness connector.

Stop engine, then turn the ignition switch to the
“Run” position.

Connect test light from 05743837 Jumper Harness
cavity “E” to ground.

Is test light “on?”

—

Go to step 6.

Go to step 5.

Repair open or short to ground in ignition feed circuit
to 2-3 shift solenoid valve.
Was a problem found and corrected?

—

Go to step 15.

—

Install a test lamp between cavity E and cavity B of
the jumper harness (0574837).

Using the transmission output control function on
the scan tool, command the 2-3 shift solenoid valve
“ON” and “OFF” three times.

Does the test lamp illuminate when the shift solenoid is
commanded “ON” and turn off when the shift solenoid
is commanded “OFF”?

—

Go to step 9.

Go to step 7.

Inspect circuit 315 (YL) for an open or short to ground.
Was an open or short to ground condition found?

—

Go to step 15.

Go to step 8.

Replace PCM.
Is the replacement complete?

—

Go to step 16.

—

Turn ignition off.

Connect 05743837 Jumper Harness to transmis-
sion 20-way connector.

With aDVOM and Connector Test Adapter Kit,
measure resistance between terminals “B” and “E.”

Is resistance within the indicated values?

19-31

Ω

Go to step 11.

Go to step 10.

Disconnect the transmissions internal wiring har-
ness from the 2-3 shift solenoid.

With a DVOM measure the resistance the 2-3 shift
solenoid.

Is resistance within indicated values?

19-31

Ω

Go to step 13.

Go to step 14.

With a DVOM, measure resistance between terminals
“B” to ground and “E” to ground.
Are both readings greater than indicated value?

250K

Ω

Go to Diag-

nostic Aids

Go to step 12.

Disconnect the transmission internal wiring har-
ness from the 2-3 shift solenoid.

With a DVOM, measure the resistance from sole-
noid terminals to ground.

Are both readings greater than indicated value?

250K

Ω

Go to step 13.

Go to step 14

Replace the automatic transmission wiring harness
assembly.
Is the replacement complete?

—

Go to step 13.

—

DTC P0758 2-3 Shift Solenoid B Electrical (Cont’d)

Step

Action

Value

Yes

3-1-01

Content .. 73 74 75 76 ..