Diagnostic Test

WARNING: This page is about a different car, the 2018 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

VERIFY THE DTC IS ACTIVE
NOTE:
This DTC must be active for the results of this test to be valid.
1. Turn the ignition on.
2. With the scan tool, read and record the DTCs.
3. With the scan tool, erase the DTCs.
4. Start the engine.
5. With the scan tool, read and record the DTCs.
  Is the DTC active at this time?
  
  Yes
  - Go To 2
  No
  - Go To 6
CHECK THE FUSE
1. Ignition on, engine not running.
2. Using a 12-volt test light connected to ground, check the fuse for power.
  Is the fuse good?
  
  Yes
  - Go To 3
  No
  - If the related fuse is open, check the (F946) Fused Ignition (RUN/START) Control Output circuits for a short to ground.
  - Perform the FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
(F946) FUSED IGNITION (RUN-START) CONTROL OUTPUT CIRCUIT SHORT TO VOLTAGE
1. Turn ignition off.
2. Disconnect the FDCM harness connector.
3. With a 12-volt test light connected to ground, check the (F946) Fused Ignition (RUN/START) Control Output circuit in the FDCM harness 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
  - Repair the (F946) Fused Ignition (RUN/START) Control Output circuits for a short to voltage.
  - Perform the FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Go To 3
(F946) FUSED IGNITION (RUN-START) CONTROL OUTPUT CIRCUIT FOR AN OPEN OR HIGH RESISTANCE
1. Ignition on, engine not running.
2. With a 12-volt test light connected to ground check (F930) Fused Ignition Switch Output (RUN/START) circuits in the FDCM harness 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 5
  No
  - Repair the (F946) Fused Ignition (RUN/START) Control Output circuits for an open or high resistance.
  - Perform the FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
(Z904) GROUND CIRCUITS FOR AN OPEN OR HIGH RESISTANCE
1. Turn the ignition off.
2. With a 12-volt test light connected to (B+) check (Z904) Ground circuit in the FDCM harness 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
  - Replace the Final Drive Control Module (FDCM) in accordance with the Service Information. Refer to REMOVAL . .
  - Perform the FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Repair the (Z904) Ground circuits for an open or high resistance.
  - Perform the FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
INTERMITTENT WIRING AND CONNECTORS
1. Using the wiring diagram/schematic as a guide, inspect the wiring harness and connectors.
2. Wiggle test the wiring harness and connectors while monitoring the scan tool data relative to this circuit.
3. Look for the data to change or for the DTC to reset during the wiggle test.
4. While monitoring the scan tool data relative to this circuit, move the selector switch to each position several times.
5. Look for the data to change other than as expected or for the DTC to reset.
  Were any problems found?
  
  Yes
  - Repair as necessary.
  - Perform the FDCM VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Test complete, the condition or conditions that originally set this DTC are not present at this time.