Diagnostic Test

WARNING: This page is about a different car, the 2017 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

CHECK FOR AN ACTIVE DTC
1. With the scan tool, read the Body Control Module (BCM) DTCs and record on the repair order.
  Is the DTC active?
  
  Yes
  - Go To 2
  No
  - Perform the TESTING FOR AN INTERMITTENT CONDITION procedure. Refer to TESTING FOR AN INTERMITTENT CONDITION .
CHECK THE (X4) HORN RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
NOTE:
Make sure the Horn Switch is not pressed when performing this step.
1. Turn the ignition off.
2. Remove the Horn Relay from the Front Power Distribution Center (PDC).
3. Turn the ignition on.
4. Measure the voltage between ground and the (X4) Horn Relay Control circuit at the Horn Relay cavity in the Front PDC.
  Is there any voltage present?
  
  Yes
  - Repair the short to voltage in the (X4) Horn Relay Control circuit.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To 3
CHECK THE (X4) HORN RELAY CONTROL CIRCUIT FOR AN OPEN
1. Turn the ignition off.
2. Disconnect the BCM C1/A harness connector.
3. Measure the resistance of the (X4) Horn Relay Control circuit between the BCM C1/A harness connector and the Horn Relay cavity in the Front PDC.
  Is the resistance above 3.0 Ohms?
  
  Yes
  - Repair the open in the (X4) Horn Relay Control circuit.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Go To 4
CHECK THE HORN RELAY
1. Connect the BCM C1/A harness connector.
2. Turn the ignition on.
3. Press and hold the Horn Switch.
  NOTE:
  The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
4. Using a 12-volt test light connected to ground, check the (X4) Horn Relay Control circuit at the Horn Relay cavity in the Front PDC.
  Does the test light illuminate brightly?
  
  Yes
  - Replace the Horn Relay in accordance with the Service Information.
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .
  No
  - Replace the Body Control Module (BCM) in accordance with the Service Information. Refer to MODULE, BODY CONTROL (BCM), REMOVAL .
  - Perform the BODY VERIFICATION TEST. Refer to BODY VERIFICATION TEST .