FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
Courtesy of Operation CHARM: Car repair manuals for everyone.
Home >> Dodge or Ram Truck >> 2012 >> RAM 3500 Truck 2WD L6-6.7L DSL Turbo High Output >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P1593

P1593






P1593-SPEED CONTROL SWITCH 1 STUCK

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

- When Monitored:
With the ignition on.

- Set Condition:
Cruise Switch inputs are not coherent with each other. Example: The Powertrain Control Module (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 may be the result of pressing two Speed Control Switch buttons simultaneously for more than 450 msec.

2. Ask the customer if it is possible that two buttons were pressed at the same time before this DTC set. If this is the case, no repair is necessary.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. SPEED CONTROL SWITCHES
1. Turn the ignition off.
2. Disconnect the Speed Control Switch harness connector.
3. Measure the resistance across each Speed Control Switch sense circuit.
4. Monitor the Ohmmeter while pressing each function button.
5. The following resistance specs are taken between terminals (V37) S/C Switch Sense 1 circuit and the (V937) Switch 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/Decel - 4.34k Ohms
- Cancel - 1.24k Ohms
- Resume/Accel - 8.80k Ohms

6. The following resistance specs are taken between terminals (V38) S/C Switch Sense 2 circuit and the (V937) Switch Return circuit of the switch when holding the switch button in the following position:
- Not pressing any switch - 20.5k Ohms
- On/Off - 6.2k Ohms
- Set/Decel - 0.79k Ohms
- Cancel - 3.2k Ohms
- Resume/Accel - 1. kOhms

Does the function on the Speed Control Switch have the correct resistance value +/- 0.2 Ohm?

Yes

- Go To 3

No

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

3. S/C SWITCH SIGNAL CIRCUIT SHORTED TO VOLTAGE




1. Disconnect the Clockspring C2 harness connector.
2. Turn the ignition on.
3. Measure the voltage on the (V37) and (V38) S/C Switch Sense circuits in the Clockspring C2 harness connector.






Is the voltage reading above 5.2 volts for either circuit?

Yes

- Repair the short to voltage in the (V37) or (V38) S/C Switch Sense circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. S/C SWITCH SENSE CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance between ground and the (V37) S/C Switch Sense 1 circuit in the Clockspring C2 harness connector.





4. Measure the resistance between ground and the (V38) S/C Switch Sense 2 circuit in the Clockspring C2 harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 5

No

- Repair the short to ground in the (V37) or (V38) S/C Switch Sense circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. S/C SWITCH SENSE CIRCUIT SHORTED TO THE (V937) S/C SWITCH RETURN CIRCUIT




1. Measure the resistance between the (V37) S/C Switch Sense circuit and the (V937) S/C Switch Return circuit in the Clockspring C2 harness connector.





2. Measure the resistance between the (V38) S/C Switch Sense circuit and the (V937) S/C Switch Return circuit in the Clockspring C2 harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 6

No

- Repair the short between the (V37) or (V38) S/C Switch Sense circuit and the (V937) Switch Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

6. CLOCKSPRING
1. Disconnect the Clockspring C8 harness connector.
2. Measure the resistance of the (V37) S/C Switch Sense 1 circuit between the Clockspring C2 and C8 on the Clockspring.
3. Measure the resistance of the (V38) S/C Switch Sense 2 circuit between the Clockspring C2 and C8 on the Clockspring.
4. Measure the resistance of the (V937) Switch Return circuit between the Clockspring C2 and C8 on the Clockspring.

Is the resistance above 5.0 Ohms for any of the circuits?

Yes

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

No

- Go To 7

7. STEERING WHEEL JUMPER HARNESS




1. Measure the resistance of the (V37) S/C Switch Sense 1 circuit between the Clockspring C8 harness connector and S/C Switch harness connector.
2. Measure the resistance of the (V38) S/C Switch Sense 2 circuit between the Clockspring C8 harness connector and S/C Switch harness connector.
3. Measure the resistance of the (V937) Switch Return circuit between the Clockspring C8 harness connector and S/C Switch harness connector.

Is the resistance above 5.0 Ohms for any of the circuits?

Yes

- Replace the Steering Wheel Jumper harness.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 8

8. S/C SWITCH SENSE CIRCUIT OPEN
1. Reconnect the PCM C2 harness connector.
2. Measure the resistance of the (V37) and (V38) S/C Switch Sense circuits between the Clockspring C2 harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms for each measurement?

Yes

- Go To 9

No

- Repair the excessive resistance in the (V37) or (V38) S/C Switch Sense circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

9. (V937) S/C SWITCH RETURN CIRCUIT OPEN
1. Measure the resistance of the (V937) S/C Switch Return circuit between the Clockspring C2 harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 10

No

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

10. SPEED CONTROL SWITCH VOLTAGE VALUES
1. Reconnect the Speed Control Switch harness connector.
2. Reconnect the Clockspring harness connectors.
3. Reconnect the PCM C2 harness connector.
4. Back probe the (V37) S/C Switch Sense 1 circuit and the (V38) S/C Switch Sense 2 circuit at the PCM C2 harness connector.

CAUTION: Use only approved back probe tools when back probing a connector so as not to cause damage to the terminals or insulation of the connector. Damage to the terminals can cause poor terminal contact or retention. Damage to the insulation can introduce corrosion due to water infiltration.

5. Turn the ignition on.
6. Using the scan tool, monitor the S/C Switch voltage readings.
7. Using a Voltmeter check the voltage on the (V37) S/C Switch Sense 1 circuit and the (V38) S/C Switch Sense 2 circuit at the PCM C2 harness connector.
8. Monitor the Voltmeter.
9. Using the scan tool, monitor the S/C Switch voltage readings.





10. 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 Volt difference between the Voltmeter switch values and the scan tool switch value?

Yes

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

No

- Go To 11

11. 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.

pro multis Credits:Operation CHARM About Operation CHARM