P1593

P1593-SPEED CONTROL SWITCH 1/2 STUCK





For a complete wiring diagram Refer to Diagrams/Electrical.


- 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.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview .


Diagnostic Test


1. ACTIVE DTC
Start the engine and allow it to idle for at least 60 seconds.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.


NOTE: It may be necessary to test drive the vehicle and operate the speed control in order for this DTC to set.

With a scan tool, select View DTCs.
Is the DTC Active at this time?

Yes


- Go To 2


No


- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition



2. 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?

Yes


- Go To 3


No


- Replace the Speed Control Switch that had the incorrect resistance value.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test



3. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO 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 there any voltage present?

Yes


- Repair the short to voltage in the (V37) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 4



4. (V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO VOLTAGE




Measure the voltage of the (V38) S/C Switch No.2 Signal circuit in the S/C Switch harness connector.
Is there any voltage present?

Yes


- Repair the short to voltage in the (V38) S/C Switch No.2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 5



5. (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?

Yes


- Go To 6


No


- Repair the open in the (V37) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test



6. (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?

Yes


- Go To 7


No


- Repair the open in the (V38) S/C Switch No.2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test



7. (V937) S/C SWITCH RETURN OPEN




NOTE: The measurement must be taken from both Speed Control Switch harness connectors.

Measure the resistance of the (V937) S/C 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?

Yes


- Go To 8


No


- Repair the open in the (V937) S/C Switch Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test



8. (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.
Is the resistance below 100 ohms?

Yes


- Repair the short to ground in the (V37) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 9



9. (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.
Is the resistance below 100 ohms?

Yes


- Repair the short to ground in the (V38) S/C Switch No.2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 10



10. (V37) S/C SWITCH NO.1 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT




Measure the resistance between the (V37) S/C Switch No.1 Signal circuit and the (V937) S/C Switch Return circuit in the Speed Control harness connector.
Is the resistance below 5.0 ohms?

Yes


- Repair the short between the (V937) S/C Switch Return circuit and the (V37) S/C Switch No.1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 11



11. (V38) S/C SWITCH NO.2 SIGNAL CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT




Measure the resistance between the (V38) S/C Switch No.2 Signal circuit and the (V937) S/C Switch Return circuit in the Speed Control harness connector.
Is the resistance below 5.0 ohms?

Yes


- Repair the short between the (V937) S/C Switch Return circuit and the (V38) S/C Switch No.2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 12



12. SPEED CONTROL SWITCH VOLTAGE VALUES
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 and #8815-1 to perform diagnosis.

Install Miller Special Tool #8815-1 on the C3 PCM harness connector.
Connect the S/C Switch harness connectors.
Connect the Clockspring harness connectors.
Turn the ignition on.
With a scan tool, monitor the S/C Switch voltage readings.
Using a voltmeter check the voltage on the (V37) S/C Switch No.1 Signal circuit and the (V38) S/C Switch No.2 Signal circuit at the appropriate terminals of the special tool #8815.
Monitor the voltmeter.
With a scan tool, monitor the S/C Switch voltage readings.






Compare the voltage readings on the voltmeter to what the scan tool displayed.
Are the voltage readings out of the listed specification and do you less than a 0.2 of a volt difference between the voltmeter switch values and the scan tool switch value?

Yes


- Verify that there is good pin to terminal contact in the Switch and Powertrain Control Module connectors. Replace the Speed Control Switch if no problems are found in the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Go To 13



13. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Speed Control Switch and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Switch and Powertrain Control Module connectors.
Refer to any Technical Service Bulletins that may apply.
Were there any problems found?

Yes


- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test


No


- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test