Hummer H1 (2002+). Manual — part 65

____________________________________________

Transmission/Transfer Case 5-59

®

05745159

DTC P0712 Fluid Temperature Circuit Low/High

Step

Action

Value

Yes

No

1

Perform transmission fluid checking procedure.
Was the fluid checking Procedure performed?

—

Go to Step

2

—

2

1.

Install the scan tool.

2.

Turn the ignition switch to “on” position.

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.

3.

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

Does the scan tool display a “TFT Sensor” signal voltage less than
shown in the value column?

0.2 volts

Go to Step

3

Refer to

Diagnostic

Aids

3

1.

Turn the ignition “off.”

2.

Disconnect the transmission 20-way harness connector.

3.

Turn the ignition “on.”

Does the scan tool display a “TFT Sensor” signal voltage greater than
shown in the value column?

4.92 volts

Go to Step

4

Go to Step

8

4

1.

Install 05743837 Jumper Harness on transmission side of the 20-
way connector.

2.

Using multimeter and Connector Test Adapter Kit, measure resis-
tance between terminals “L” and “M.”

Is resistance high?

Check

charging

system

Refer to

Diagnostic

Aids

Go to Step

6

5

1.

Remove transmission oil pan.

2.

Check the internal wiring harness for a short to ground.

Was a problem found?

—

Go to Step

7

Go to Step

6

6

1.

Disconnect the internal wiring harness.

2.

Measure the resistance of TFT sensor.

Is the resistance high?

—

Refer to

Diagnostic

Aids

Go to Step

7

7

Replace the internal wiring harness.
Is the replacement complete?

—

Go to Step

11

—

8

Check circuit 359 for short to ground.
Was a problem found?

—

Go to Step

11

Go to Step

9

9

Check the TCM/PCM for faulty connections.
Was a problem found?

—

Go to Step

11

Go to Step

10

10

Replace the TCM/PCM.
Is the replacement complete?

—

Go to Step

11

—

11

1.

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

2.

Select “Specific DTC” and enter DTC “P0712.”

3.

Ensure the following conditions are met:

• TFT sensor indicates a voltage greater than 0.33 volts for 10 sec-

onds.

Has the last test failed?

—

Begin

diagnosis

again, Go

to Step 1

Repair ver-

ified, exit

DTC table.

5-60

Transmission/Transfer Case

_____________________________________________

®

DTC P0713 Transmission Fluid Temperature
(TFT) Sensor Circuit - High Input (Low Tem-
perature Indicated)

Circuit Description

The transmission fluid temperature (TFT) sensor is a ther-
mister that controls signal voltage to the PCM which supplies a
5-volt reference signal to the sensor on circuit 359. When the
transmission fluid is cold sensor resistance is high and the
TCM/PCM will sense high signal voltage. As fluid tempera-
ture warms to normal operating temperature of 100° C (212°
F), sensor resistance increases and the voltage drops to about
1.5 to 2 volts.

This DTC detects a continuous open or short to power in the
signal circuit or the sensor.

Conditions For Setting DTC

• TFT sensor indicating a voltage greater than 4.92 volts.

• Ignition is “on.”

• All conditions met for 50.5 seconds.

Action Taken When DTC Sets

• Transmission default temperature will be 140° C (275° F).

NOTE:

Scan tool will not display default temperature

• Freeze 1-2 shift adapts from being updated.

• The PCM will illuminate the warning light.

Conditions For Clearing DTC

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

secutive ignition cycles without a failure reported.

• The DTC can be cleared from the PCM with 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 DTC default actions when the

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

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

____________________________________________

Transmission/Transfer Case 5-61

®

05745159

Diagnostic Aids

• Check harness for a faulty connection or an open in cir-

cuit.

• Inspect 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.

• Scan tool displays transmission fluid temperature in de-

grees. After transmission is operating, the temperature
should rise steadily to about 100° C (212° E7), then sta-
bilize.

• The temperature to resistance value scale may be used

to check the TFT sensor at various temperature levels to
evaluate the possibility of a “skewed” (mis-scaled) sen-
sor. A “skewed” sensor can result in harsh shifts or con-
verter clutch complaints.

• 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.

2. This check verifies a problem in the TFT sensor circuit.

3. This test simulates a TFT sensor DTC P0712. If the

TCM/PCM recognizes the low signal voltage (high
temperature), and the scan tool displays 146° C
(295° F) or greater, the TCM/PCM and wiring are OK.

4. This test checks the TFT sensor and internal wiring

harness.

5-62

Transmission/Transfer Case

_____________________________________________

®

DTC P0713 Fluid Temperature Low

Step

Action

Value

Yes

No

1

Perform the transmission fluid checking procedure.
Was the fluid checking Procedure performed?

—

Go to Step 2

—

2

1.

Install the scan tool.

2.

With the engine “off,” turn the ignition switch
“on.”

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.
3.

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

Does the scan tool display a “TFT Sensor” signal volt-
age less than shown in the value column?

4.92 volts

Go to Step 3

Go to Diag-

nostic Aids

3

1.

Turn ignition “off.”

2.

Disconnect the transmission 20-way harness con-
nector.

3.

Install the J– 39775 Jumper Harness on the engine
side of the 20-way connector.

4.

Install a fused jumper wire from terminal “L” to
“M” on the engine harness.

5.

Turn the ignition “on.”

Does the “TFT Sensor” signal voltage drop to less than
indicated in the value column?

0.2 volts

Go to Step 5

Go to Step 9

4

Turn ignition “off.”
Install 05743837 Jumper Harness on the transmission
side of the 20-way connector.
Using the multimeter and Connector Test Adapter Kit,
measure the resistance between terminals L and M.
Is the resistance high?

—

Refer to Diag-

nostic Aids

Go to Step 5

5

1.

Remove the transmission oil pan.

2.

Check the internal wiring harness for an open.

Was a problem found?

—

Go to Step 12

Go to Step 6

6

1.

Disconnect the internal wiring harness.

2.

Measure the resistance of the TFT sensor.

Is the resistance high?

__

Refer to Diag-
nostic Aids

Go to Step 7

7

Replace the internal wiring harness.
Is the replacement complete?

__

Go to Step 12

__

8

Check circuit 359 for an open or short to B+.
Was a problem found?

__

Go to Step 12

Go to Step 9

9

Check circuit 923 for an open.
Was a problem found?

__

Go to Step 12

Go to Step 10

10

Check the PCM for faulty or intermittent connections.
Was a problem found?

__

Go to Step 12

Go to Step 11