Diagnostic Test

TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.
2. Using a scan tool, record and erase Diagnostic Trouble Codes (DTCs).
3. Operate the Rear Window Defogger and the Front and if equipped Rear HVAC Controls.
4. Cycle the ignition from on to off three times and leave on.
5. Using a scan tool, read DTCs.
  Does the scan tool display: B106B-REAR DEFROST CONTROL CIRCUIT LOW?
  
  Yes
  - Go to step 2
  No
  - The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
CHECK FOR OPEN JB FUSE #24

Fig 1: Checking Fuse #24
Courtesy of CHRYSLER LLC
1. Inspect JB Fuse #24.
  Is the fuse open?
  
  Yes
  - Go to step 3
  No
  - Go to step 7
REPLACE AND RECHECK JB FUSE #24

Fig 2: Checking Fuse #24
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Install a new JB Fuse #24.
3. Turn the ignition on.
4. Operate the Rear Window Defogger and the Front and if equipped Rear HVAC Controls.
5. Inspect JB Fuse #24.
  Is the fuse open?
  
  Yes, with Rear HVAC
  - Go to step 4
  Yes, without Rear HVAC
  - Go to step 5
  No
  - Using the wiring diagram/schematic as a guide, inspect the wiring and connectors for the cause of the open fuse and repair as necessary.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
CHECK FOR A SHORTED REAR BLOWER MOTOR RELAY
1. Turn the ignition off.
2. Install a known good relay in place of the Rear Blower Motor Relay.
3. Install a new JB Fuse #24.
4. Turn the ignition on.
5. Operate the Rear Window Defogger and the Front and Rear HVAC Controls.
6. Inspect JB Fuse #24.
  Is the fuse open?
  
  Yes
  - Go to step 5
  No
  - Replace the original Rear Blower Motor Relay in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
CHECK FOR A SHORTED REAR WINDOW DEFOGGER RELAY
1. Turn the ignition off.
2. Install a known good relay in place of the Rear Window Defogger Relay.
3. Install a new JB Fuse #24.
4. Turn the ignition on.
5. Operate the Rear Window Defogger and the Front HVAC Controls.
6. Inspect JB Fuse #24.
  Is the fuse open?
  
  Yes
  - Go to step 6
  No
  - Replace the original Rear Window Defogger Relay in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
CHECK (F504) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT FOR A SHORT TO GROUND

Fig 3: Checking Fused Ignition Switch Output (Run) Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Remove JB Fuse #24.
3. Remove the replacement Rear Window Defogger Relay.
4. Remove the replacement Rear Blower Motor Relay (if equipped).
5. Disconnect the JB C2 connector.
  NOTE: Check connectors. Clean and repair as necessary.
6. Measure the resistance of the (F504) Fused Ignition Switch Output (Run) circuit between ground and the JB Fuse #24 connector.
  Is the resistance below 10K Ohms?
  
  Yes
  - Replace the Junction Block (JB) and Fuse #24 in accordance with the Service Information. Reinstall the original Rear Window Defogger Relay and if equipped Rear Blower Motor Relay.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
  No
  - Repair the (F504) Fused Ignition Switch Output (Run) Circuit to the HVAC Control(s) for a short to ground. Replace JB Fuse #24. Reinstall the original Rear Window Defogger Relay and if equipped Rear Blower Motor Relay.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
CHECK (F921) IGNITION SWITCH OUTPUT (RUN) CIRCUIT FOR AN OPEN

Fig 4: Checking Ignition Switch Output (Run) Circuit
Courtesy of CHRYSLER LLC
1. If not done previously, turn the ignition off, and then remove JB Fuse #24.
2. Turn the ignition on.
3. Using a 12-Volt test light connected to ground, check the (F921) Ignition Switch Output (Run) circuit at JB Fuse #24 connector.
  NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
  
  Does the test light illuminate brightly?
  
  Yes
  - Go to step 8
  No
  - Repair the (F921) Ignition Switch Output (Run) circuit for an open.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
CHECK (F504) FUSED IGNITION SWITCH OUTPUT (RUN) CIRCUIT FOR AN OPEN

Fig 5: Checking Fused Ignition Switch Output (Run) Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Remove the Rear Window Defogger Relay.
3. Reinstall JB Fuse #24.
4. Turn the ignition on.
5. Using a 12-Volt test light connected to ground, check the (F504) Fused Ignition Switch Output (Run) circuit at the Rear Window Defogger Relay connector.
  NOTE: The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
  
  Does the test light illuminate?
  
  Yes
  - Go to step 9
  No
  - Replace the Junction Block (JB) in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
CHECK FOR AN OPEN REAR WINDOW DEFOGGER RELAY
1. Turn the ignition off.
2. Install a known good relay in place of the Rear Window Defogger Relay.
3. Turn the ignition on.
4. Using a scan tool, erase DTCs.
5. Operate the Rear Window Defogger several times.
6. Cycle the ignition from on to off three times and leave on.
7. Using a scan tool, read DTCs.
  Does the scan tool display the same DTC?
  
  Yes
  - Go to step 10
  No
  - Replace the original Rear Window Defogger Relay in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
CHECK (C115) DEFOGGER RELAY CONTROL CIRCUIT FOR AN OPEN

Fig 6: Checking Defogger Relay Control Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Remove the replacement Rear Window Defogger Relay.
3. Disconnect the FCM from the Front Control Module IPM 49-way connector.
4. Measure the resistance of the (C115) Defogger Relay Control circuit between the Rear Window Defogger Relay connector and the Front Control Module IPM 49-way connector.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Go to step 11
  No
  - Repair the (C115) Defogger Relay Control circuit for an open.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
CHECK (C115) DEFOGGER RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND

Fig 7: Checking Defogger Relay Control Circuit
Courtesy of CHRYSLER LLC
1. Measure the resistance of the (C115) Defogger Relay Control circuit between ground and the Rear Window Defogger Relay connector.
  Is the resistance below 10K Ohms?
  
  Yes
  - Repair the (C115) Defogger Relay Control circuit for a short to ground.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
  No
  - Replace the Front Control Module (FCM) in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .