Diagnostic Test

ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)
1. Start the engine and allow it to idle for at least 60 seconds.
  WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.
  
  NOTE: It may be necessary to test drive the vehicle and operate the speed control in order for this DTC to set.
2. With a scan tool, select View DTCs.
  Is the DTC Active at this time?
  
  Yes
  - Go to step 2
  No
  - Perform the INTERMITTENT CONDITION diagnostic procedure. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
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 4.7 Volts?
  
  Yes
  - Replace the Speed Control Switch.
  - Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
  No
  - Go to step 3
(V72) S/C SIGNAL 2 CIRCUIT SHORTED TO GROUND

Fig 1: Checking S/C Signal Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the C3 PCM harness connector.
3. Measure the resistance between ground and the (V72) S/C Signal 2 circuit in the 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. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
  No
  - Go to step 4
(V72) S/C SIGNAL 2 CIRCUIT SHORTED TO THE (V937) S/C SWITCH GROUND CIRCUIT

Fig 2: Checking S/C Signal Circuit
Courtesy of CHRYSLER LLC
1. Measure the resistance between the (V72) S/C Signal 2 circuit and the (V937) S/C Switch Ground circuit in the Switch harness connector.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Repair the short between the (V72) S/C Signal 2 circuit and the (V937) S/C Switch Ground circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
  No
  - Go to step 5
EXCESSIVE RESISTANCE IN THE (V72) S/C SIGNAL 2 CIRCUIT

Fig 3: Checking S/C Signal 2 Circuit
Courtesy of CHRYSLER LLC

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. Measure the resistance of the (V72) S/C Signal 2 circuit from the Speed Control Switch to the appropriate terminal of PCM Pinout Box 8815.
  Is the resistance below 5.0 Ohms for each measurement?
  
  Yes
  - Go to step 6
  No
  - Repair the excessive resistance in the (V72) S/C Signal 2 circuit.
  - Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .

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.

Using a Voltmeter check the voltage on the (V38) S/C Signal 2 circuit at the appropriate terminals of the PCM Pinout Box 8815.
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.
Start the engine and allow it to reach normal operating temperature.
Monitor the Voltmeter.
Allow the engine to idle.

With a scan tool, monitor the S/C Switch voltage readings.

SWITCH POSITION	SWITCH No. 1 VOLTAGE VALUE	SWITCH No. 2 VOLTAGE VALUE
NO SWITCHES PRESSED	4.31 to 4.78 Volts	4.31 to 4.78 Volts
ON/OFF PRESSED	0.59 to 1.13 Volts	3.53 to 3.92 Volts
RES/ACCEL PRESSED	3.88 to 4.17 Volts	2.04 to 2.47 Volts
SET PRESSED	3.16 to 3.56 Volts	1.17 to 1.56 Volts
COAST PRESSED	2.57 to 2.94 Volts	0.77 to 1.09 Volts
CANCEL PRESSED	1.59 to 1.99 Volts	2.84 to 3.25 Volts

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 Switches and Powertrain Control Module connectors. Replace the Speed Control Switch if no problems were found in the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
No
- Go to step 7

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. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .
  No
  - Replace and program the Powertrain Control Module in accordance with the service information.
  - Perform the POWERTRAIN VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure .