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When Monitored:
Ignition on, In plant mode passed the Applied test.
Set Condition:
PCM recognizes the Brake Pedal could not electronically indicate the released (Off) position with both
switches. If P1572 sets, P1573 will also set. One trip fault.
Possible Causes
(V32) BRAKE SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
(B29) BRAKE SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
STOP LAMP SWITCH
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
NOTE: Make sure the Stop Lamp Switch is adjusted properly before continuing.
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.STOP LAMP SWITCH OPERATION
Turn the ignition off.
Disconnect the Stop Lamp Switch harness connectors.
Measure the resistance between the (Z429) Ground circuit terminal and the(B29) Brake Switch No.1 Signal terminal
in the Stop Lamp Switch.
Apply and release the brake pedal while monitoring the ohmmeter.
Does the resistance change from below 5.0 ohms to an open circuit when pressing and releasing the
brake switch?
Ye s>>
Go To 3
No>>
Replace the Stop Lamp Switch.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
3.STOP LAMP SWITCH OPERATION
Measure the resistance between the (V30) Fused Ignition Switch Output circuit terminal and the (V32) Brake Switch
No.2 Signal terminal in the Stop Lamp Switch.
Apply and release the brake pedal while monitoring the ohmmeter.
Does the resistance change from below 5.0 ohms to an open circuit when pressing and releasing the
Stop Lamp switch?
Ye s>>
Go To 4
No>>
Replace the Stop Lamp Switch.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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4.(V32) BRAKE SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Disconnect the C2 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (V32) Brake Switch No.2 Signal circuit in
the Stop Lamp Switch harness connector.
Is the voltage above 1.0 volt?
Ye s>>
Repair the short to battery voltage in the (V32) Brake
Switch No.2 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
5.(B29) BRAKE SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Measure the resistance between ground and the (B29) Brake Switch
No.1 Signal circuit in the Stop Lamp Switch harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (B29) Brake Switch No.1
Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 6
6.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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P1593-SPEED CONTROL SWITCH 1/2 STUCK
For a complete wiring diagramRefer to Section 8W.
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When Monitored:
Ignition on.
Set Condition:
One of the S/C Switches is mechanically stuck in the On/Off, Resume/Accel,or Set position for too long. One
trip fault.
Possible Causes
(V37) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN
(V38) S/C SWITCH NO.2 SIGNAL CIRCUIT OPEN
(V937) SWITCH RETURN CIRCUIT OPEN
(V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
(V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
(V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
(V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO GROUND
(V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT
(V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT
SPEED CONTROL SWITCH
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.SPEED CONTROL SWITCH NO.1 STUCK
Start the engine.
With a scan tool, monitor each switch function for the Speed Control Switches.
Press and release each Speed Control Button.
Is Switch No.1 Stuck?
Ye s>>
Replace the Speed Control Switch.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 2
2.SPEED CONTROL SWITCH STATUS
Start the engine.
With a scan tool, monitor each switch function for the Speed Control Switches.
Press and release each Speed Control Button.
- Resume/Accel
-Cancel
- Decel (Coast)
-On/Off
-Set
Does each switch function change status when pressing and releasing each switch?
Ye s>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
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3.SPEED CONTROL SWITCHES
Turn the ignition off.
Remove the Speed Control Switches from the steering wheel.
Measure the resistance across each Speed Control Switch.
Monitor the ohmmeter while pressing each function button on each switch.
The following resistance specs are taken between terminals (V38) S/C Switch No.2 Signal and (V937) S/C Switch
Return circuit of the Switch when holding the switch button in the following position.
On/Off - 8.87 kohms
Set - 0.825 kohms
Coast - 0.47 kohms
Cancel - 3.92 kohms
Resume/Accel - 1.87 kohms
The following resistance specs are taken between terminals (V37) S/C Switch No.1 Signal and (V937) S/C Switch
Return circuits of the Switch when holding the switch button in the following position
On/Off - 0.47 kohms
Set - 5.49 kohms
Coast - 2.94 kohms
Cancel - 1.24 kohms
Resume/Accel - 15.4 kohms
Does the function on the Speed Control Switches have the correct resistance value?
Ye s>>
Go To 4
No>>
Replace the Speed Control Switch that had the incorrect resistance value.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
4.(V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Ignition on, engine not running.
Measure the voltage of the (V37) S/C Switch No.1 Signal circuit in the
S/C Switch harness connector.
Is the voltage above 5.0 volts?
Ye s>>
Repair the short to voltage in the (V37) S/C Switch No.1
Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 5
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5.(V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Measure the voltage of the (V38) S/C Switch No.2 Signal circuit in the
S/C Switch harness connector.
Is the voltage above 5.0 volts?
Ye s>>
Repair the short to voltage in the (V38) S/C Switch No.2
Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 6
6.(V37) S/C SWITCH NO.1 SIGNAL CIRCUIT OPEN
Turn the ignition off.
CAUTION: Do not probe the PCM harness connectors. Probing the
PCM harness connectors will damage the PCM terminals resulting
in poor terminal to pin connection. Install Miller Special Tool #8815
to perform diagnosis.
Measure the resistance of the (V37) S/C Switch No.1 Signal circuit from
both Speed Control harness connectors to the appropriate terminals of
special tool #8815.
Is the resistance below 5.0 ohms for both measurements?
Ye s>>
Go To 7
No>>
Repair the open in the (V37) S/C Switch No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
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7.(V38) S/C SWITCH NO.2 SIGNAL CIRCUIT OPEN
Measure the resistance of the (V38) S/C Switch No.2 Signal circuit from
both Speed Control harness connectors to the appropriate terminals of
special tool #8815.
Is the resistance below 5.0 ohms for both measurements?
Ye s>>
Go To 8
No>>
Repair the open in the (V38) S/C Switch No.2 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
8.(V937) SWITCH RETURN OPEN
NOTE: The measurement must be taken from both Speed Control
Switch harness connectors.
Measure the resistance of the (V937) Switch Return circuit from the
Speed Control harness connector to the appropriate terminal of special
tool #8815.
Is the resistance below 5.0 ohms for both measurements?
Ye s>>
Go To 9
No>>
Repair the open in the (V937) Switch Return circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
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9.(V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (V37) S/C Switch No.1
Signal circuit in the Speed Control harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (V37) S/C Switch No.1
Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 10
10.(V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (V38) S/C Switch No.2
Signal circuit in the Speed Control harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (V38) S/C Switch No.2
Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 11