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P0593







P0593-SPEED CONTROL SWITCH 2 CIRCUIT HIGH





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the ignition on.

- Set Condition:
The S/C Switch #2 Signal is above 4.78 volts for 0.06 seconds.





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

Diagnostic Test

1. S/C SWITCH VOLTAGES OUT OF RANGE




Turn the ignition on.
With the scan tool, monitor the S/C Switch signal voltages.
Press each button while noting the voltage readings for each circuit.
Are the S/C Switch voltages within the ranges specified in the table when each button is pressed?

Yes

Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Intermittent Condition

No

- Go To2

2. (V72) S/C SWITCH NO. 2 SIGNAL CIRCUIT VOLTAGE




Turn the ignition off.
Disconnect both Speed Control Switch harness connectors.
Turn the ignition on.
Measure the voltage of the (V72) S/C Switch No. 2 Signal circuit at both Speed Control Switch harness connectors.
Select the appropriate voltage reading.

4.5 to 5.5 volts at both connectors.

- Go To3

4.5 to 5.5 volts at only one connector.

- Repair the (V72) S/C Switch No. 2 Signal circuit that measured below 4.5 volts for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 4.Verification Tests

Below 4.5 volts at both connectors.

- Go To6

Above 5.5 volts for either measurement.

- Go To8

3. (V937) S/C SWITCH GROUND CIRCUIT OPEN CIRCUIT OR HIGH RESISTANCE




Turn the ignition off.
Disconnect the Engine Control Module (ECM) harness connector.
Measure the resistance of the (V937) S/C Switch Ground circuit between each Speed Control Switch harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 10.0 ohms for both circuits?

Yes

- Go To4

No

- Repair the (V937) S/C Switch Ground circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 4.Verification Tests

4. (V937) S/C SWITCH GROUND CIRCUIT SHORTED TO VOLTAGE




Turn the ignition off.
Remove the ASD Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.
Turn the ignition on.
Measure the voltage of the (V937) S/C Switch Ground circuit.
Is there any voltage present?

Yes

- Repair the (V937) S/C Switch Ground circuit for a short to voltage.
- Perform the ECM Verification Test Ver. 4.Verification Tests

No

- Go to 5

5. S/C SWITCHES




Turn the ignition off.
Remove the jumper wire and install the ASD relay.
Connect the Engine Control Module (ECM) harness connector.
Turn the ignition on.
With the scan tool, monitor the S/C Switch Voltage.
While monitoring the scan tool, connect a jumper wire between the (V72) S/C Switch No. 2 Signal circuit and the (V937) S/C Switch Ground circuit in the S/C Switch harness connector.
Does the scan tool display below 0.1 volt with the jumper wire in place?

Yes

- Replace the Speed Control Switches.
- Perform the ECM Verification Test Ver. 4.Verification Tests

No

- Go to 9

6. (V72) S/C SWITCH NO. 2 SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE




Turn the ignition off.
Disconnect the Engine Control Module (ECM) harness connector.
Measure the resistance of the (V72) S/C Switch No. 2 Signal circuit between each Speed Control Switch harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 10.0 ohms for both measurements?

Yes

- Go To7

No

- Repair the (V72) S/C Switch No. 2 Signal circuit for an open circuit or high resistance.
- Perform the ECM Verification Test Ver. 4.Verification Tests

7. (V72) S/C SWITCH NO. 2 SIGNAL CIRCUIT SHORTED TO GROUND




Measure the resistance between ground and the (V72) S/C Switch No. 2 Signal circuit.
Is the resistance above 1000 ohms?

Yes

- Go to 9

No

- Repair the (V72) S/C Switch No. 2 Signal circuit for a short to ground.
- Perform the ECM Verification Test Ver. 4.Verification Tests

8. (V72) S/C SWITCH NO. 2 SIGNAL CIRCUIT SHORTED TO VOLTAGE




Turn the ignition off.
Disconnect the Engine Control Module (ECM) harness connector.
Remove the ASD Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.
Turn the ignition on.
Measure the voltage of the (V72) S/C Switch No. 2 Signal circuit.
Is there any voltage present?

Yes

- Repair the (V72) S/C Switch No. 2 Signal circuit for a short to voltage.
- Perform the ECM Verification Test Ver. 4.Verification Tests

No

- Go to 9

9. ENGINE CONTROL MODULE (ECM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Speed Control Switch and the Engine Control Module (ECM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the ECM Verification Test Ver. 4.Verification Tests

No

- Replace the Engine Control Module (ECM).
- Perform the ECM Verification Test Ver. 4.Verification Tests
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