Hummer H1 (2002+). Manual — part 71

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Transmission/Transfer Case 5-83

®

05745159

DTC P0741 Torque Converter Clutch Solenoid Stuck OFF

FUSE 2A

10A

EXTERIOR

C33-F

351 PK

C34

D

C

S

B

A

M

L

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

5-84

Transmission/Transfer Case

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®

Circuit Description

The PCM energizes the converter clutch solenoid by creating a
ground path on CKT 924. When grounded (energized) by the
PCM, enable solenoid stops converter signal oil from exhaust-
ing. This causes converter signal oil pressure to increase and
shift the valve. The solenoid will de-energize when the PCM
no longer provides a ground path. When the solenoid is de-en-
ergized, it will exhaust fluid and release the TCC.This DTC de-
tects high torque converter slip when the clutch is engaged.

Conditions For Setting DTC

• No DTCs P0121, P0122, P0220, P0221, P0222, P0223,

P0225, P0226, P0227, or P0228.

• No DTC P0722, P0723.

• No DTCs P0716 or P0717.

• No DTCs P0742 or P1860.

• No DTC P1810.

• No DTC P1860.

• Converter clutch commanded on in 2nd or 3rd for more

than 0.6 seconds.

• Engine running for at least 5 seconds.

• Converter clutch applied for more than 0.6 seconds.

• Transmission in 2nd or 3rd.

• Throttle Position greater than 20%.

• Pressure switch in D4, D3, or D2.

• Transmission fluid temperature between -10° C (14° F)

and 150° C (302° F).

• Converter clutch slip speed is greater than 65 rpm for

4 seconds.

• All conditions must be met for a total of 2 occurrences.

Action Taken When DTC Sets

• PCM will inhibit converter clutch apply.

• PCM will inhibit 4th gear upshift.

• The PCM will illuminate the warning lamp.

Conditions For Clearing DTC

• The PCM will turn the warning light off after three con-

secutive ignition cycles without a failure reported. The
DTC can be cleared using the scan tool. The DTC will
clear 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 long enough to power down the
PCM.

Diagnostic Aids

• Inspect the wiring for poor electrical at the PCM and the

transmission 20-way connector. Look for possible bent,
backed out, deformed or damaged terminals. Check for
weak terminal tension as well. Also, check for chafed
wire that could short to bare metal or other wiring In-
spect for broken wire inside the insulation.

• 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.

____________________________________________

Transmission/Transfer Case 5-85

®

05745159

DTC P0742 Torque Converter Clutch Stuck On

FUSE 2A

10A

EXTERIOR

C33-F

351 PK

C34

D

C

S

B

A

M

L

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

5-86

Transmission/Transfer Case

_____________________________________________

®

Circuit Description

The PCM energizes the converter clutch solenoid by creating a
ground path on circuit 924. When grounded (energized) by the
PCM, the solenoid stops converter signal oil from exhausting.
This causes converter signal oil pressure to increase and move
the clutch valve. The solenoid will de-energize when the PCM
no longer provides a ground path. When the solenoid is de-en-
ergized, it will exhaust fluid and release the converter clutch.

This DTC detects low torque converter slip when the clutch is
commanded OFF.

Conditions For Setting DTC

The following conditions occur once per TCC cycle two con-
secutive times:

• No DTCs P0121, P0122, P0220, P0221, P0222, P0223,

P0225, P0226, P0227, or P0228.

• No engine speed DTC P0219.

• No DTCs, P0716 or P0717.

• No DTCs P0741 or P1860.

• No DTC P1810.

• No DTCs.

• Engine speed is less than 3650 RPM.

• Engine running for greater than 5 seconds. \

• Engine torque between 80 and 450 ft/lbs.

• Gear range is D4.

• Commanded gear must be 2nd, 3rd, or 4th.

• No engine torque malfunctions.

• Throttle Position must be greater than 10%.

• TCC slip speed must be between -15 RPM and +20

RPM for at least 5 seconds.

• All conditions met for 3 occurrences.

Action Taken When DTC Sets

• The PCM will command maximum line pressure.

• The PCM will freeze shift adapts.

• The PCM will turn on the warning lamp.

Conditions For Clearing DTC

• The PCM will turn off the warning lamp after three con-

secutive ignition cycles without a failure reported.

• The DTC can be cleared using the scan tool.

• The PCM will cancel DTC default actions when the

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

Diagnostic Aids

• If the converter clutch is seized with the parking brake

applied and any gear range selected, the clutch fluid
pressure will apply the clutch and cause an engine stall.

• If any engine DTCs codes are present diagnose and

clear these DTCs first. Then check to see if the transmis-
sion DTCs have reset.