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P1593






P1593-SPEED CONTROL SWITCH 1/2 STUCK





For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
Ignition on.

- Set Condition:
Cruise Switch inputs are not coherent with each other. Example: PCM is reading Switch No.1 as Accel and Switch No.2 as Coast at the same time. One trip fault.





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

1. ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)
1. Ignition on, engine not running.

NOTE: This DTC is a two trip fault. If the scan tool indicates a one trip failure, the possible cause may have been the customer pressing the switch in two positions simultaneously. Test drive the vehicle and activate the Speed Control system. If the DTC matures to an active fault a repair is necessary.

2. Ask the customer if it is possible that button was held in two positions at the same time before this DTC set. If this is the case, no repair is necessary.
3. Start the engine.
4. Allow the engine to reach normal operating temperature.
5. With a scan tool, select View DTCs.

NOTE: It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.

Is the DTC Active or Pending at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. . Intermittent Condition Test

2. SPEED CONTROL SWITCH
1. Using the scan tool, monitor the Speed Control Switch voltage.
2. Disconnect the Speed Control Switch harness connector.

Did the voltage change to above 4.8 Volts?

Yes

- Replace the Speed Control Switch.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. SPEED CONTROL SWITCHES
1. Turn the ignition off.
2. Remove and disconnect the Speed Control Switch from the steering wheel.
3. Measure the resistance across each Speed Control Switch.
4. Monitor the Ohmmeter while pressing each function button on each switch.
5. The following resistance specs are taken between terminals (V72) S/C Signal 2 circuit and (V937) S/C Return circuit 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

6. The following resistance specs are taken between terminals (V71) S/C Signal 1 and (V937) S/C Return circuit of the Switch when holding the switch button in the following position:
- Not pressing any switch - 20.5k Ohms
- On/Off - 0.47k Ohms
- Set - 5.49k Ohms
- Coast - 2.94k Ohms
- Cancel - 1.24k Ohms
- Resume/Accel - 15.4k Ohms

Does the function on the Speed Control Switch have the correct resistance value?

Yes

- Go To 4

No

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

4. (V71) S/C SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE




1. Disconnect the C3 PCM harness connector.
2. Measure the voltage on the (V71) S/C Signal 1 circuit at the Speed Control harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the (V71) S/C Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO VOLTAGE




1. Measure the voltage on the (V72) S/C Signal 2 circuit at the Speed Control harness connector.

Is there any voltage present?

Yes

- Repair the short to voltage in the (V72) S/C Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. (V71) S/C SIGNAL 1 CIRCUIT OPEN





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 PCM Pinout Box 8815 to perform diagnosis.

1. Turn the ignition off.
2. Measure the resistance of the (V71) S/C Signal 1 circuits from the Speed Control harness connector to the appropriate terminal of PCM Pinout Box 8815.

Is the resistance below 5.0 Ohms for each measurement?

Yes

- Go To 7

No

- Repair the excessive resistance in the (V71) S/C Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

7. (V72) S/C SIGNAL 2 CIRCUIT OPEN




1. Measure the resistance of the (V72) S/C Signal 2 circuit from the Speed Control harness connector to the appropriate terminal of PCM Pinout Box 8815.

Is the resistance below 5.0 Ohms for each measurement?

Yes

- Go To 8

No

- Repair the excessive resistance in the (V72) S/C Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

8. (V937) S/C RETURN CIRCUIT OPEN





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

1. Measure the resistance of the (V937) S/C Return circuit at the Speed Control harness connector to the appropriate terminal of PCM Pinout Box 8815.

Is the resistance below 5.0 Ohms for both measurements?

Yes

- Go To 9

No

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

9. (V71) S/C SIGNAL 1 CIRCUIT SHORTED TO THE (V937) S/C RETURN CIRCUIT




1. Measure the resistance between the (V937) S/C Return circuit and both of the (V71) S/C Signal 1 circuit in the S/C Switch harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Repair the short between the (V937) S/C Return circuit and the (V71) S/C Switch Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 10

10. (V72) S/C SIGNAL 2 CIRCUIT SHORTED TO THE (V937) S/C RETURN CIRCUIT




1. Measure the resistance between the (V937) S/C Return circuit and both of the (V72) S/C Signal 2 circuit in the S/C Switch harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Repair the short between the (V937) S/C Return circuit and the (V72) S/C Switch Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 11

11. (V71) S/C SIGNAL 1 CIRCUIT SHORTED TO THE (V72) S/C SIGNAL 2 CIRCUIT




1. Measure the resistance between the (V71) S/C Signal 1 circuit and the (V72) S/C Signal 2 circuit at the Speed Control harness connector.

Is the resistance below 100 Ohms for each circuit?

Yes

- Repair the short between the (V72) S/C Signal 2 circuit and the (V71) S/C Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 12

12. (V71) S/C SWITCH SIGNAL 1 CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (V71) S/C Switch Signal 1 circuit at the S/C Switch harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the (V71) S/C Signal 1 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 13

13. (V72) S/C SWITCH SIGNAL 2 CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (V72) S/C Switch Signal 2 circuit at the S/C Switch harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the (V72) S/C Signal 2 circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 14

14. 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 PCM Pinout Box 8815 and PCM Pinout Box Adapter 8815-1 to perform diagnosis.

1. Install the PCM Pinout Box 8815-1 on the C3 PCM harness connector.
2. Connect the S/C Switch harness connectors.
3. Connect the Clockspring harness connectors.
4. Turn the ignition on.
5. With a scan tool, monitor the S/C Switch voltage readings.
6. Using a Voltmeter check the voltage on the (V37) S/C Signal 1 circuit and the (V38) S/C Signal 2 circuit at the appropriate terminals of the PCM Pinout Box 8815.
7. Monitor the Voltmeter.
8. With a scan tool, monitor the S/C Switch voltage readings.
9. Compare the voltage readings on the Voltmeter to what the scan tool displayed.

Are the voltage readings out of the listed specification and is there less than a 0.2 of a Volt difference between the Voltmeter switch values and the scan tool switch values?

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 15

15. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Speed Control Switch and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. 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.
4. Perform 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.

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