Page 721 of 5267
4.
Reconnect the brake switch connector.
Using the scan tool, clear the DTC’s.
Turn the ignition on.
Cycle the brake pedal several times.
Using the scan tool, read the DTC’s.
Has the brake switch low DTC returned?
Ye s>>
Replace the brake switch.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Perform Intermittent condition test. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Page 722 of 5267
P0573-HIGH VOLTAGE DETECTED AT THE BRAKE SWITCH
For a complete wiring diagramRefer to Section 8W.
Page 723 of 5267

When Monitored:
While the ignition is on.
Set Condition:
The brake switch status is = to ON and the not brake switch status is = to OFF for a calibrated amount of time.
Possible Causes
DAMAGED WIRING HARNESS OR CONNECTORS
BRAKE SWITCH CIRCUIT OPEN (BRAKE SWITCH WILL ALWAYS BE ON)
BRAKE SWITCH CIRCUIT SHORTED TO BATTERY VOLTAGE (BRAKE SWITCH WILL ALWAYSBE ON)
BRAKE SWITCH
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
1.BRAKE SWITCH CIRCUIT OPEN
Turn the ignition off.
Disconnect the brake switch connection. Inspect the pins and connector
for damage, corrosion, etc.
Disconnect the ECM connectors. Inspect the pins and connector for
damage, corrosion, etc.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the brake switch signal circuits in the
ECM connector and the brake switch connector.
Is the resistance less than 10 ohms?
Ye s>>
Go To 2
No>>
Repair the open brake switch circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 724 of 5267

2.BRAKE SWITCH CIRCUIT SHORTED TO VOLTAGE
Measure the voltage between the brake switch circuits in the ECM con-
nector and battery negative.
Is the voltage less than 1 volt?
Ye s>>
Go To 3
No>>
Repair the open circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
3.ECM
Reconnect the ECM connectors.
Install a jumper wire in the brake switch connector between signal circuitand to ground.
Turn the ignition on.
Cycle the brake pedal several times.
Using the scan tool, read the DTC’s.
Is the DTC for brake switch low voltage present?
Ye s>>
Go To 4
No>>
Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
4.BRAKE SWITCH
Reconnect the brake switch connector.
Using the scan tool, clear the DTC’s.
Turn the ignition on.
Cycle the brake pedal several times.
Using the scan tool, read the DTC’s.
Has the brake switch High DTC returned?
Ye s>>
Replace the brake switch.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Perform Intermittent condition test. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Page 725 of 5267
P0580-LOW VOLTAGE DETECTED AT THE SPEED CONTROL SWITCH
For a complete wiring diagramRefer to Section 8W.
Page 726 of 5267

When Monitored:
While the ignition is on
Set Condition:
Speed control MUX switch below 1.0 volts for 5 seconds.
Possible Causes
S/C WIRING HARNESS OBSERVABLE PROBLEM
S/C SWITCH (ON/OFF)
CLOCKSPRING SHORTED TO GROUND
S/C SWITCH (RESUME/ACCEL)
S/C SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
S/C SIGNAL CIRCUIT SHORTED TO SENSOR GROUND
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.S/C SWITCH VOLTAGE BELOW 1.0 VOLT
Turn the ignition on.
With the scan tool, read the S/C Switch volts status in the ECM.
Is the S/C Switch voltage below 1.0 volt?
Ye s>>
Go To 3
No>>
Go To 2
2.S/C WIRING HARNESS OBSERVABLE PROBLEM
Turn the ignition off.
Using the Schematics as a guide, inspect the Wiring and Connectors.
Were any problems found?
Ye s>>
Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 3
3.S/C SWITCH (ON/OFF)
Turn the ignition off.
Disconnect the S/C ON/OFF Switch harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Turn the ignition on.
With the scan tool in Sensors, read the S/C Switch volts in the ECM.
Did the S/C Switch volts change to 5.0 volts?
Ye s>>
Replace the S/C ON/OFF Switch.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 4
Page 727 of 5267

4.S/C SWITCH (RESUME/ACCEL)
Turn the ignition off.
Disconnect the S/C RESUME/ACCEL Switch harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
With the scan tool in Sensors, read the S/C Switch volts in the ECM.
Did the S/C Switch volts go above 4.0 volts?
Ye s>>
Replace the Resume/Accel Switch.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 5
5.CLOCKSPRING SHORTED TO GROUND
Turn the ignition off.
Disconnect the clockspring6-way harness connector (instrument panel
wiring side).
Turn the ignition on.
With the scan tool in Sensors, read the S/C Switch volts in the ECM.
Did the S/C Switch volts change to 5.0 volts?
Ye s>>
Replace the Clockspring.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
No>>
Go To 6
6.S/C SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the S/C ON/OFF Switch harness connector.
Disconnect the ECM harness connectors.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the S/C Switch Signal circuit and
ground (B-) at S/C ON/OFF Switch harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Repair S/C Switch Signal Circuit for a short to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
No>>
Go To 7
Page 728 of 5267
7.S/C SIGNAL CIRCUIT SHORTED TO SENSOR GROUND
Measure the resistance between the S/C Signal Circuit and the Sensor
Ground Circuit at the ON/OFF switch harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Repair S/C Signal Circuit shorted to Sensor Ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
No>>
Replace and program the ECM in accordance with the Ser-
vice Information.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)