2012 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

P0579-S/C SWITCH 1 SIGNAL CIRCUIT PLAUSIBILITY

P0579-S/C SWITCH 1 SIGNAL CIRCUIT PLAUSIBILITY

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



Possible Causes

HIGH RESISTANCE IN THE (V71) S/C SIGNAL 1 CIRCUIT
HIGH RESISTANCE IN THE (V937) S/C SWITCH RETURN CIRCUIT
SPEED CONTROL SWITCH
STEERING WHEEL JUMPER HARNESS
CLOCKSPRING
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


1. DTC IS ACTIVE

1. Ignition on, engine not running.
2. With the scan tool, Clear DTCs in the PCM.
3. Start the engine and test drive the vehicle.
4. During the test drive select each of the speed control switch positions.
5. With the scan tool, select View DTCs.


Is the status Active for this DTC?

Yes


No


2. CHECK FOR HIGH RESISTANCE IN THE SPEED CONTROL SWITCH CIRCUITS

1. Turn the ignition off.
2. Disconnect the Speed Control Switch harness connector.
3. Disconnect the PCM C2 harness connector.
4. Measure the resistance of the (V71) S/C Signal 1 circuit between the PCM C2 harness connector and Speed Control Switch harness connector.
5. Measure the resistance of the (V937) Switch Return circuit between the PCM C2 harness connector and Speed Control Switch harness connector.


Is the resistance below 5.0 Ohms for both measurements?

Yes


No


3. SPEED CONTROL SWITCH

1. Turn the ignition off.
2. Disconnect the Speed Control Switch harness connector in accordance with the service information.
3. Measure the resistance between the (V71) S/C Signal 1 terminal and the (V937) S/C Switch Return terminal at the Speed Control Switch, not the harness connector.
4. Monitor the Ohmmeter while pressing each function button on each switch.
5. The following resistance specs are taken between terminals (V71) S/C Signal 1 terminal and the (V937) Switch Return terminal 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


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

Yes


No


4. POWERTRAIN CONTROL MODULE

1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Speed Control Switch and the Powertrain Control Module.
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.


Were any problems found?

Yes


No


5. STEERING WHEEL JUMPER HARNESS
1. Turn the ignition off.
2. Disconnect the Clockspring C8 harness connector.
3. Measure the resistance of the (V71) S/C Signal 1 circuit between the Clockspring C8 harness connector and Speed Control Switch harness connector.
4. Measure the resistance of the (V937) Switch Return circuit between the Clockspring C8 harness connector and Speed Control Switch harness connector.


Is the resistance below 5.0 Ohms for both measurements?

Yes


No


6. CLOCKSPRING
1. Disconnect the Clockspring C2 harness connector.
2. Measure the resistance of the (V71) S/C Signal 1 circuit between the Clockspring C2 and PCM C2 harness connectors.

3. Measure the resistance of the (V937) Switch Return circuit between the Clockspring C2 and PCM C2 harness connectors.


Is the resistance below 5.0 Ohms for both measurements?

Yes


No