Diagnostic Test

WARNING: This page is about a different car, the 2011 RAM Dakota. However, it is still accessible from the selected car via links, so may be relevant.

INTERMITTENT CONDITION
1. Turn the ignition on.
2. With the scan tool, clear all FCM DTCs
3. Actuate the Trailer Tow Lamps.
4. With the scan tool, read DTCs.
  Does the scan tool read: B166F-RIGHT TRAILER TOW LAMP CONTROL CIRCUIT LOW?
  
  Yes
  - Go To 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. Refer to BODY VERIFICATION TEST .
PDM FUSE 21
1. Using a 12-volt test light connected to ground, check the IPM Fuse 21.
  Does the test light illuminate and was the fuse OK?
  
  No
  - Replace the IPM Fuse 21 if open and check for a short to ground on the Relay Output circuit or correct the open B(+) circuit to the fuse.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  Yes
  - Go To 3.
OPEN FUSED B(+) TO RELAY
1. Remove the Trailer Tow Relay from the IPM.
2. Using a 12-volt test light connected to ground, check the Fused B(+) circuit at the relay connector.
  Does the test light illuminate?
  
  No
  - Replace the IPM.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  Yes
  - Go To 4.
RIGHT TRAILER TOW RELAY
1. Install a known good relay in place of the Trailer Tow Relay.
2. With the scan tool erase DTCs
3. Cycle the ignition from on to off 3 times and leave on.
4. With the scan tool, read DTCs.
  Does the scan tool display the same DTC?
  
  No
  - Replace the original Trailer Tow Relay.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  Yes
  - Go To 5.
(L656) TRAILER TOW RELAY CONTROL SHORTED

Fig 1: Checking Trailer Tow Relay Control For A Short
Courtesy of CHRYSLER LLC
1. Remove the Right Trailer Tow Relay.
2. Disconnect the Front Control Module from the IPM 49-way connector.
3. Measure the resistance between ground and the (L656) Trailer Tow Relay Control circuit at the relay.
  Is the resistance below 1000.0 Ohms?
  
  Yes
  - Replace the IPM.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To 6.
(L656) TRAILER TOW RELAY CONTROL OPEN

Fig 2: Checking Trailer Tow Relay Control For A Short
Courtesy of CHRYSLER LLC
1. Measure the resistance of the (L656) Trailer Tow Relay Control circuit from the relay connector to FCM connector.
  Is the resistance below 3.0 Ohms?
  
  Yes
  - Replace the Front Control Module.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Replace the IPM.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .