P0593

P0593-SPEED CONTROL SWITCH 2 CIRCUIT HIGH




For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.
- When Monitored:
Key on or Engine running.

- Set Condition:
Speed Control MUX switch above 11.5 Volts for five seconds.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. SCAN TOOL SHOWS SPEED CONTROL SWITCH ON/OFF
1. Turn the ignition on.
2. With the scan tool in Inputs/Outputs, read the Speed Control inputs state in ECM.
3. While monitoring the scan tool, push the Speed Control On/Off Switch several times, then leave it on.

Did the scan tool show Speed Control Switch off and on?

Yes

- Perform the INTERMITTENT DTC diagnostic procedure.Intermittent Condition Test

No

- Go To 2

2. S/C WIRING HARNESS VISUAL INSPECTION
1. Turn the ignition off.
2. Using the Schematics as a guide, inspect the Wiring and Connectors.

Were any problems found?

Yes

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

No

- Go To 3

3. CLOCKSPRING




1. Disconnect the C1 and C3 Clockspring harness connectors.

NOTE: Check connectors - Clean/repair as necessary.

2. Measure the resistance of the (V937) S/C Switch Return circuit between the C1 and C3 Clockspring harness connectors.





3. Measure the resistance of the (V38) S/C Switch 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 (DIESEL). Powertrain Verification Test.

No

- Go To 4

4. SPEED CONTROL ON/OFF SWITCH
1. Disconnect the Speed Control On/Off Switch harness connector only.

NOTE: Check connectors - Clean/repair as necessary.

2. Measure the resistance across the S/C On/Off Switch.

Is the resistance between 20.3K and 20.7K Ohms?

Yes

- Go To 5

No

- Replace the On/Off Switch.
- Perform the POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test.

5. (V38) S/C SWITCH 2 SIGNAL CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition on.
2. Measure the voltage of the (V38) S/C Switch 2 Signal circuit at both S/C Switch harness connectors.

Is the voltage above 6.0 Volts?

Yes

- Repair the (V38) S/C Switch 2 Signal circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test.

No

- Go To 6

6. (V38) S/C SWITCH 2 SIGNAL CIRCUIT OPEN ECM TO CLOCKSPRING
1. Turn the ignition off.
2. Disconnect the ECM harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the resistance of the (V38) S/C Switch Signal 2 circuit between the ECM connector and the C1 Clockspring harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 7

No

- Repair open in the (V38) S/C Switch 2 Signal circuit between the ECM and the Clockspring.
- Perform the POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test.

7. (V38) S/C SWITCH 2 SIGNAL CIRCUIT OPEN CLOCKSPRING TO S/C SWITCH
1. Measure the resistance of the (V38) S/C Switch 2 Signal circuit from the C3 Clockspring harness connector to the S/C Switch harness connectors.

Is the resistance below 5.0 Ohms?

Yes

- Go To 8

No

- Repair the open in the (V38) S/C Switch 2 Signal circuit between the Clockspring and the S/C switches.
- Perform the POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test.

8. (V937) S/C SWITCH RETURN CIRCUIT OPEN BETWEEN THE CLOCKSPRING AND S/C SWITCHES
1. Measure the resistance of the (V937) S/C Switch Return circuit between the S/C harness connectors to the C3 Clockspring harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 9

No

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

9. (V937) S/C SWITCH RETURN CIRCUIT OPEN BETWEEN THE ECM AND CLOCKSPRING
1. Measure the resistance of the (V38) S/C Switch Return circuit between the ECM harness connector and the C1 Clockspring harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Replace and program the ECM. Programming and Relearning
- Perform the POWERTRAIN VERIFICATION TEST (DIESEL). Powertrain Verification Test.

No

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