P0593

P0593-SPEED CONTROL SWITCH 2 CIRCUIT HIGH





For a complete wiring diagram Consult Diagrams/Electrical.

- When Monitored:
With the ignition key on.

- Set Condition:
Speed Control Switch No.2 input above the maximum acceptable voltage at the PCM. 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
Disconnect and 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 circuits of the Switch when holding the switch button in the following position.
Not pressing any switch - 20.5k ohms
On/Off - 8.87k ohms
Set - 0.825k ohms
Coast - 0.47k ohms
Cancel - 3.92k ohms
Resume/Accel - 1.87k ohms
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. CLOCKSPRING








Disconnect the C1 and C3 Clockspring harness connectors.
Measure the resistance of the (V937) S/C Switch Return circuit between the upper and lower clockspring harness connectors.
Measure the resistance of the (V38) S/C Switch No.2 Signal circuit between the C1 and C3 Clockspring harness connectors.
Was the resistance above 5.0 ohms for either circuit?

Yes

- Replace the clockspring.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 4

4. (V38) SIGNAL NO.2 CIRCUIT SHORTED TO VOLTAGE




Connect the C1 and C3 Clockspring harness connectors.
Disconnect the C3 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (V38) S/C Signal No.2 circuit in the Speed Control harness connector.
Is there any voltage present

Yes

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

No

- Go To 5

5. (V38) S/C SWITCH NO.2 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 (V38) S/C Switch No.2 Signal circuit from the both Switch harness connectors to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?

Yes

- Go To 6

No

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

6. (V937) S/C SWITCH RETURN CIRCUIT OPEN




Measure the resistance of the (V937) S/C Switch Return circuit from the both Switch harness connectors to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?

Yes

- Go To 7

No

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

7. 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.
Search for 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