Hummer H1 (2002+). Manual - part 296

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PCM/Tech 1 Scan Tool 117

05745159

DTC P1654 Check Throttle Circuit

Circuit Description

A dash light is illuminated by the PCM if diagnostics have de-
tected certain errors related to the Accelerator Pedal Position
(APP) sensor. Illumination is accomplished by the PCM pro-
viding a ground path for the light circuit. This is a type D DTC.

Conditions for Setting the DTC

• Check Throttle lamp requested “ON”.

• Voltage at the Check Throttle control circuit is greater

than 0 volts.

• Check Throttle lamp requested “OFF”.

• Voltage at the Check Throttle control circuit is equal to

0 volts.

Action Taken When the DTC Sets

Will not turn “ON” the MIL.

Conditions for Clearing the MIL/DTC

• The PCM will turn the MIL off after three consecutive

trips without a fault condition.

• 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

A faulty bulb or the control circuit shorted to ground will cause
a P1654 to set.

Test Description

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

2. This test checks the ability of the PCM to command the

Check Throttle lamp on during the bulb check (Check
Throttle lamp should be “ON” for 2 seconds and then go
out).

3. This test will check the control circuit for a short to ground.

6. This test will check the control circuit for an open.

FUSE 2D
20 AMP
INTERIOR

STS

LAMP

MIL

LAMP

FUSE 3A
20 AMP
EXTERIOR

HOT AT
ALL TIMES

HOT IN RUN
AND START

HOT IN RUN

AND START

FUSE 4B
5 AMP
INTERIOR

FUSE 1H
5 AMP
INTERIOR

DLC

POWERTRAIN

CONTROL

MODULE

SERIAL DATA

CLASS II

MIL

CONTROL

STS LAMP

CONTROL

914 PP

59 BK

C28-C8

570 BK

C28-D7

C28-D6

GROUND

570 BK

BATT

IGN

C28-C13

C28-D13

C28-C12

C28-C11

C28-D11

C29-B3

537 OR

239 PK

C1-10

C10-J

C10-H

C10-C

C3-G5

C3-F3

C1-25

C1-28

C28-C14

658 BR

714 RD

STATUS
CENTER

HOT AT

ALL TIMES

9-S12-064

554 GRY

118

PCM/Tech 1 Scan Tool

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DTC P1654 - Check Throttle 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. Ignition “ON” engine “OFF”.
2. Using a scan tool, command the lamp ON and OFF.

Does the Check Throttle lamp turn ON and OFF with each command?

—

Go to Step 3.

Go to Step 4.

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

applicable

DTC table.

Go to

Diagnostic Aids

1. Ignition “OFF”.
2. Disconnect the blue 32 way PCM electrical connector.

3. Ignition “ON” engine “OFF”.

Is the lamp “OFF”?

—

Go to Step 5.

Go to Step 7.

With a fused jumper wire connected to ground, probe the lamp control cir-
cuit in the PCM harness connector.
Is the lamp ON?

—

Go to Step 6.

Go to Step 8.

1. Check for poor connections at PCM.
2. If a problem was found, repair as necessary.

Was a repair performed?

—

Go to Step 10. Go to Step 9.

Check Throttle control circuit is shorted to ground.
Is the action complete?

—

Go to Step 10.

—

Check the Check Throttle control circuit for the following:

• opens

• poor connection at PCM

• faulty bulb

• faulty fuse.

Was a problem found?

—

Go to Step 10.

—

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 10.

—

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 11.

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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PCM/Tech 1 Scan Tool 119

05745159

DTC P1656 Wastegate Solenoid Control
Circuit

Circuit Description

The turbocharger wastegate is a vacuum actuated valve used to
control the exhaust gas heat sent to the turbo. The wastegate
pulse width modulated solenoid meters the vacuum level at the
wastegate valve actuator as commanded by the PCM. When
the PCM is commanding the Wastegate solenoid ON, the volt-
age potential of the circuit will be low (near 0 volts). When the
PCM is commanding the wastegate solenoid OFF, the voltage
potential of the circuit will be high (near battery volts). The
primary function of the PCM in this circuit is to supply the
ground for the wastegate solenoid. This is a type B code.

Conditions for Setting the DTC

• Conditions for Setting the DTC
• PCM requested Wastegate solenoid ON.
• Voltage on Wastegate solenoid control circuit high

(near battery volts).

• 2 consecutive faults detected.
• Conditions met for 2 seconds.
• or
• PCM requested Wastegate solenoid OFF.
• Voltage on Wastegate solenoid control circuit low (near

0 volts).

• 2 consecutive faults detected.
• Conditions met for 2 seconds.

Action Taken When the DTC Sets

Low Power.

Conditions for Clearing the MIL/DTC

• The PCM will turn the MIL off after three consecutive

trips without a fault condition.

• 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 Tool.

Diagnostic Aids

This diagnostic will set when control circuit does not follow
the PCM command (when the solenoid is requested ON volt-
age will drop, when the solenoid is OFF ignition voltage will
be present). The scan tool has a 5 second ON time abort. The
wastegate solenoid can be commanded ON for as many times
as needed, in 5 second intervals. Its possible DTC P0236 may
set along with DTC P1656. This diagnostic can be checked
during key up. The engine will not respond to scan tool com-
mands at idle (engine unable to achieve boost pressures greater
than BARO at idle) or at any engine speed greater than idle
(PCM control abort to prevent engine damage).

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

120

PCM/Tech 1 Scan Tool

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Test Description

Number(s) below refer to the step number(s) on the Diagnostic
Table.
2. Be sure that both the ON and OFF states are commanded.

Repeat the commands as many times as necessary.

3. This check can detect a partially shorted coil which would

cause excessive current flow. Leaving the circuit energized
for 2 minutes allows the coil to warm up. When warm, the
coil may open (Amps drop to zero), or short (Amp draw
greater than 0.75A).

14.If no trouble is found in the control circuit or the connection

at the PCM, the PCM may be malfunctioning. However, this
is an extremely unlikely failure.

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