Hummer H1 (2006+). Manual - part 98

OBD-236

On-Board Diagnostics

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1.Turn the ignition OFF.

2.Disconnect TCM C79.

3.Using the DVOM and the J 35616-C, in sequence, test the sig-
nal circuits 591 (DB), 592 (GY), 594 (DG), and 593 (WH) be-
tween C79 of the TCM and 591 (DB), 592 (GY), 594 (DG), and
593 (WH) of the NSBU switch 12-way connector for a short to
voltage condition.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

Test the signal circuits of the NSBU switch that did not indicate
proper voltage for an open or short to ground.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

NOTE: A scan tool must be used in order to clear the code from
the TCM history.

Replace the faulty NSBU switch.

Did you complete the replacement?

Go to Step 10

NOTE: In most cases, the TCM is not at fault. Investigate thor-
oughly before replacing the TCM.

Replace the faulty TCM.

Did you complete the replacement?

Go to Step 10

Perform the following procedure in order to verify the repair:

Clear the DTC.

Using the scan tool, monitor the TR Sw. display while select-
ing each transmission range, P, R, N, D4, D3, D2, and D1.

Select Specific DTC.

Enter DTC P0708.

Has the test run and passed?

System OK

Go to Step 1

Step

Action

Value(s)

Yes

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On-Board Diagnostics OBD-237

5745804

DTC P0711 Transmission Temperature Sensor Circuit Performance (Figure OBD-66)

Figure OBD-66: Transmission Temperature Sensor Circuit

Circuit Description

The transmission fluid temperature (TFT) sensor is a part of the pressure switch manifold (PSM) assembly, and is located in the
transmission oil pan. The TFT sensor is a thermistor, which changes value based on the temperature of the transmission fluid. The
sensor has a negative-temperature coefficient. This means that as the temperature increases, the resistance decreases, as the temper-
ature decreases the resistance increases. The transmission control module (TCM) supplies a 5 volt reference voltage signal to the
TFT sensor and measures the voltage drop in the circuit. When the transmission is cold, the sensor resistance is high and the TCM
detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the
signal voltage decreases. The TCM uses this information to control shift quality and torque converter clutch (TCC) apply.

DTC P0711 is a type B DTC.

Conditions for Setting the DTC

DTC P0711 sets when the TCM detects one of the following conditions:

• The TCM detects a temperature change that is below a set limit when compared to samples of the minimum and maximum

temperature values.

• The TFT has an unrealistic temperature change of greater than 10°C (50°F) for 10 occurrences.

• The temperature from startup decreases 40°C (104°F) or greater within a duration of 6 seconds or greater.

OBD-238

On-Board Diagnostics

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Action Taken When the DTC Sets

• The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for

Setting the DTC are met.

• The TCM freezes shift adapts.

• The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this informa-

tion as Failure Records.

• The TCM stores DTC P0711 in TCM history.

• The TCM inhibits TCC engagement.

Conditions for Clearing the DTC

A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle com-
pletes 40 warm-up cycles without failure.

Diagnostic Aids

• The TFT should rise steadily during warm-up cycles, then stabilize.

• DTC P0218 may set after DTC P0711 has set. Follow the diagnostic table for DTC P0711 before proceeding to the diagnos-

tic for DTC P0218.

• Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions:

• A bent terminal

• A backed-out terminal

• A damaged terminal

• Poor terminal tension

• A chafed wire

• A broken wire inside the insulation

• When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a

change.

• You may have to drive the vehicle in order to experience a condition.

• An open condition at circuit 2762 may allow a ground path internally through circuit 2471. If this occurs, the TCM sees a

temperature that appears to be within normal operation, approximately -22°C (-7.6°F), and initially a code will not be
set. However, the transmission will still inhibit shift adapts and TCC operation. It may take several minutes before P0711
code is set to indicate a failure.

Step

Action

Value(s)

Yes

NOTE: Before clearing DTC(s) use the scan tool “Capture info”
to record Freeze Frame and Failure Records for reference, as data
will be lost when “Clear Info” function is used

Was the “On-Board Diagnostic (OBD) System Check” per-
formed?

Go to step 2.

Go to OBD Sys-

tem Check.

Measure the transmission fluid level.

Refer to Transmission Fluid Checking Procedure.

Is the transmission fluid level correct?

Go to Step 3

Go to Transmis-

sion Fluid

Checking Proce-

dure

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On-Board Diagnostics OBD-239

5745804

Install the scan tool.

Turn ON the ignition, with the engine OFF.

NOTE: Before clearing the DTC, use the scan tool in order to
record the Freeze Frame and Failure Records for reference. The
Clear Info function will erase the data.

Record the DTC Freeze Frame and Failure Records.

Clear the DTC.

Select TFT on the scan tool.

Drive the vehicle and look for an unrealistic TFT reading.

Is the TFT reading at or below the specified value?

1.5°C

(2.7°F)

Go to Step 4

Go to Diagnos-

tic Aids

Turn the ignition OFF.

Disconnect C79 at the TCM.

Install the J 39700 breakout box and the J 43799 breakout
box adapter at C79.

Turn ON the ignition, with the engine OFF.

Use a DVOM, measure voltage at C79 terminal 10 and ter-
minal 20.

Is the voltage within the specified value?

5 Volts

Go to Step 5

Go to Step 11

Turn the ignition OFF.

Using a DVOM, measure resistance at C79 terminal 10 and
terminal 20.

Is the resistance within the specified value?

3,490

ohms

[commat]

20°C

(68°F)

177.9

ohms

[commat]

100°C

(212°F)

Go to Diagnos-

tic Aids

Go to Step 6

Turn the ignition OFF.

Disconnect the transmission 20-way C34.

Using a DVOM, measure resistance at the transmission side
of the 20-way connector between terminals G and H.

Is the resistance within the specified value?

3,490

ohms

[commat]

20°C

(68°F)

177.9

ohms

[commat]

100°C

(212°F)

Go to Step 8

Go to Step 7

Step

Action

Value(s)

Yes

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