Hummer H1 (2002+). Manual - part 289

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PCM/Tech 1 Scan Tool 89

05745159

DTC P0501 Vehicle Speed Sensor Circuit

Circuit Description

The speed sensor circuit consists of a magnetic induction type
sensor, a Digital Ratio Adaptor (DRA) and wiring. Geared
teeth pressed on the output shaft induce an alternating current
in the sensor. This A/C signal is transmitted to the DRA. The
DRA compensates for various axle ratios and converts the sig-
nal into a digital signal for use by the speedometer, cruise con-
trol, and the PCM. The DRA sends two different signal to the
PCM. Circuit 565 sends a signal of 40 pulses per revolution of
the output shaft to the PCM. This signal is used to control shift
points, line pressure, TCC and diagnostic codes. Circuit 223
sends a signal of 4000 pulses per mile to the PCM. This signal
is used to control engine operating functions, cruise control
and DTCs.When DTC P0501 or P0723 is set, second gear only at
a maximum line pressure will occur. This is a type D DTC.

Conditions for Setting the DTC

• Vehicle speed greater than 20 m.p.h.

• Four wheel low not selected.

• VSS buffer calculated speed is less than half the trans-

mission calculated speed.

• VSS buffer calculated speed is greater than transmission

calculated speed by 20 m.p.h.

• All conditions met for 2 seconds.

Action Taken When the DTC Sets

No cruise control.

Conditions for Clearing the MIL/DTC

• A History DTC will clear when forty consecutive

warm-up cycles that the diagnostic does not fail (coolant
temperature has risen 5°C (40°F) from start up coolant
temperature and engine coolant temperature exceeds
71°C (160°F) that same ignition cycle).

• Use of a scan.

Diagnostic Aids

Check connections at VSS buffer and PCM. Refer to
4L80EDiagnostic Diagnostic Trouble Codes, Section 10 if
DTC P0722 or DTC P0723 is also set.

Test Description

Number(s) below refer to the number(s) on the diagnostic table.

3. This tests for B+ at VSS buffer.

4. This tests for proper ground path for vehicle speed sensor

signal buffer.

TWISTED

PAIR

VEHICLE

SPEED

SENSOR

(VSS)

GROUND

VEHICLE

SPEED

SENSOR
RETURN

679 LG

VEHICLE

SPEED

DIGITAL RATIO ADAPTER

CRUISE

CONTROL

REFERENCE

SIGNAL

4000 PPM

SPEEDO

REFERENCE

SIGNAL

00-S12-038

+12 VOLT

IGNITION

SIGNAL

OUTPUT SHAFT

REVOLUTION

SIGNAL

570 BK

POWERTRAIN

CONTROL

MODULE

( PCM )

GROUND

4000 PPM

CRUISE

CONTROL

REFERENCE

SIGNAL

570 BK

565 BR

C29

C28

FUSE

15 AMP

570 BR

239 PK

676 PP

565 BR

353 YL

IGNITION

EXTERIOR
FUSE
BOX

C1-18

C3-P9

SPEEDO

C33

223 DB

40 PULSE

OUTPUT SHAFT
REVOLUTION

SIGNAL

TO PCM

3-1-01

PCM/Tech 1 Scan Tool

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DTC P0501 - Vehicle Speed Sensor Circuit

Step

Action

Value(s)

Yes

Important:

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” performed?

—

Go to Step 2.

Go to OBD

System Check.

1. Install scan tool.
2. Raise drive wheels.

3. Engine operating.

4. Transmission in any drive range.

With drive wheels rotating, does vehicle speed increase with drive wheel
speed increase?

—

Go to Step 7.

Go to Step 3.

1. Transmission in park.
2. Back probe VSS buffer module ignition feed circuit with a test light con-

nected to ground. Is the test light “ON”?

—

Go to Step 4.

Go to Step 8.

Back probe VSS buffer module ignition feed circuit to the ground circuit
with a test light.
Is the test light “ON”?

—

Go to Step 5.

Go to Step 9.

1. Back probe VSS buffer module at VSS input circuit (C7) to the other

VSS input circuit (C12) with a J–39200 on the AC scale.

2. Transmission in any drive range with drive wheels rotating.

Does voltage increase on J–39200 with drive wheel increase?

—

Go to Step 6.

Go to Step 10.

Does scan tool display a trans output speed (MPH) increase with drive
wheel increase?

—

Go to Step 11. Go to Step 13.

DTC is intermittent. If no additional DTCs are stored, refer to “Diagnostic
Aids”. If additional DTCs are stored, refer those charts(s) first.

Are additional DTCs stored?

—

Go to

applicable

DTC table.

Go to

Diagnostic Aids

Repair the open in the ignition feed circuit.

Is action complete?

—

Go to Step 15.

—

Repair the open in the ground circuit.

Is action complete?

—

Go to Step 15.

—

Check the complete VSS input circuit for an open or short to ground.

Was a repair performed?

—

Go to Step 15.

—

Check VSS output circuit for an open or short to ground.

Was a repair performed?

—

Go to Step 15. Go to Step 12.

Check VSS output circuit for a poor connection at buffer module and PCM.

Was a repair performed?

—

Go to Step 15. Go to Step 14.

Replace VSS buffer module.

Is action complete?

—

Go to Step 15.

—

Replace the faulty PCM. Notice: If the PCM is faulty, the new PCM must
be programmed. Go to PCM replacement and programming procedures.
Is the action complete?

—

Go to Step 15.

—

1. Using the Scan Tool, select “DTC”, “Clear Info”.
2. Start engine and idle at normal operating temperature.

3. Select “DTC”, “Specific”, then enter the DTC number which was set.

4. Operate vehicle within the conditions for setting this DTC as specified in

the supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

—

Go to Step 16.

Go to Step 2.

Using the Scan Tool, select “Capture Info”, “Review Info”.

Are any DTCs displayed that have not been diagnosed?

—

Go to the

DTC table

System OK.

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PCM/Tech 1 Scan Tool 91

05745159

DTC P0567 Cruise Resume Circuit

Circuit Description

The cruise Resume/Accel switch is an input to the fuel control
portion of the PCM. These inputs allow the PCM to control
and hold a requested speed. Cruise Resume/Accel switch sends
ignition voltage to the PCM when the switch is closed (“ON”).
This is a type D DTC.

Conditions for Setting the DTC

• Cruise switch “OFF”.

• Ignition voltage on Resume switch signal circuit.

• Cruise switch “ON”.

• Resume switch “ON” for longer than 25.5 seconds

Action Taken When the DTC Sets

• Will not turn on the MIL.

• The PCM will disallow all cruise inputs.

• TCC shift schedules may be affected.

Conditions for Clearing the MIL/DTC

• A History DTC will clear when forty consecutive

• Use of a Scan Tool.

Diagnostic Aids

Check for a resume/accel switch stuck in the engage position
or the signal circuit is shorted to voltage.

Test Description

Number(s) below refer to the number(s) on the diagnostic ta-
ble.

2. This step determines if the signal circuit is shorted to volt-

age.

3. This step determines if the PCM or switch is at fault.

FUSE 5C
10AMP
INTERIOR

FUSE 3A
10 AMP
EXTERIOR

ON/
OFF

SET
COAST

RESUME
ACCEL

HOT IN RUN
AND START

C29-A11

C29-B11

C27-D10

C28-D14

C28-C2

C27-D12

C27-D3

C27-D4

C27-D6

C29-B2

C29-B1

C27-C5

C29-A12

C5-D3

C5-A4

154 TN

151 GY

152 DB

153 LG

ON / OFF
SIGNAL

SET
COAST
SIGNAL

RESUME
ACCEL
SIGNAL

WASTEGATE
SOLENOID
CONTROL

5 VOLT
REFERENCE

APP 3
SIGNAL

GROUND

APP 1
SIGNAL

GROUND

720 TN

717 WH

723 YL

724 DG

725 GY

718 DB

719 BR

721 LB

722 PP

ACCELERATIOR
PEDAL POSITION
SENSOR

POWERTRAIN
CONTROL
MODULE
(PCM)

APP 2
SIGNAL

9-S12-055

295 BR

GRN

PCM/Tech 1 Scan Tool

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DTC P0567 - Cruise Resume Circuit

Step

Action

Value(s)

Yes

Important:

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” performed?

—

Go to Step 2.

Go to OBD

System Check.

1. Scan tool connected.
2. Ignition “ON”, engine “OFF”.

3. Cruise switch “OFF”.

Does scan tool display Resume Switch “ON”?

—

Go to Step 3.

Go to Step 4.

1. Ignition “ON”.
2. Disconnect the PCM brown 32 way connector.

3. Probe the Resume switch signal circuit at the PCM harness with a test

light connected to chassis ground.

Is the test light “ON”?

—

Go to Step 5.

Go to Step 7.

DTC is intermittent. If no additional DTCs are stored, refer to “Diagnostic
Aids”. If additional DTCs are stored, refer to those charts(s) first.

Are additional DTCs stored?

—

Go to the

applicable

DTC table

Go to

Diagnostic

Aids.

1. Resume switch signal circuit is shorted to voltage.
2. Repair as necessary.

Is action complete?

—

Go to Step 8.

—

Replace the faulty PCM. Notice: If the PCM is faulty, the new PCM must
be programmed. Go to PCM replacement and programming procedures.

Is the action complete?

—

Go to Step 7.

—

1. Using the Scan Tool, select “DTC”, “Clear Info”.
2. Start engine and idle at normal operating temperature.

3. Select “DTC”, “Specific”, then enter the DTC number which was set.

4. Operate vehicle within the conditions for setting this DTC as specified

in the supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

—

Go to Step 8.

Go to Step 2.

Using the Scan Tool, select “Capture Info”, “Review Info”.

Are any DTCs displayed that have not been diagnosed?

—

Go to the

applicable

DTC table

System OK.

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