Pinpoint Test E : Trailer Assist Lamp Is Inoperative Or Always On
WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.
- E1 CHECK THE OPERATION OF THE TRAILER ASSIST LAMP
- Ignition ON.
- Check the function of the trailer assist lamp.
Is the trailer assist lamp always on?
Yes GO to E5 No GO to E2 - E2 CHECK FOR DIAGNOSTIC TROUBLE CODES (DTCS) FROM THE DC/DC (DIRECT CURRENT/DIRECT CURRENT CONVERTER CONTROL MODULE) SELF-TEST
- Using the diagnostic scan tool, perform the DC/DC self-test.
Are any DC/DC DTC retrieved?
Yes REFER to: Direct Current/Direct Current (DC/DC) Converter Control Module . No GO to E3 - E3 CHECK FOR VOLTAGE TO THE TRAILER ASSIST LAMP
- Ignition OFF.
- Disconnect Trailer Assist Lamp C4500 .
- Ignition ON.
- Measure:
Positive Lead Measurement / Action Negative Lead C4500-3 Ground
Is the voltage greater than 11 volts?
Yes GO to E4 No REPAIR the circuit. - E4 CHECK FOR GROUND TO THE TRAILER ASSIST LAMP
Is the voltage greater than 11 volts?
Yes GO to E5 No REPAIR the circuit. - E5 CHECK THE LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect BCM C2280E .
- Disconnect Rear Lamp Fade Control Module C480 .
- Disconnect RH Headlamp Assembly C1759 .
- Disconnect LH Headlamp Assembly C1758 .
- Disconnect Trailer assist lamp C4500 (if not already disconnected).
- Ignition ON.
- Measure:
Positive Lead Measurement / Action Negative Lead C2280E-50 Ground
Is any voltage present?
Yes REPAIR the circuits. No GO to E6 - E6 CHECK THE LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure:
Positive Lead Measurement / Action Negative Lead C2280E-50 Ground
Is the resistance greater than 10, 000 ohms?
Yes GO to E7 No REPAIR the circuit. - E7 CHECK THE LIN (LOCAL INTERCONNECT NETWORK) CIRCUIT FOR AN OPEN BETWEEN THE BCM (BODY CONTROL MODULE) AND THE TRAILER ASSIST LAMP
Is the resistance less than 3 ohms?
Yes INSTALL a new trailer assist lamp. If the concern is still present after trailer assist lamp replacement, GO to E8 No REPAIR the circuit. - E8 CHECK FOR CORRECT BCM (BODY CONTROL MODULE) OPERATION
- Ignition OFF.
- Disconnect and inspect the BCM connectors
- Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary
- Reconnect the BCM connectors. Make sure they seat and latch correctly.
- Operate the system and determine if the concern is still present.
Is the concern still present?
Yes CHECK OASIS for any applicable service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, BCM guided routine is not applicable for this vehicle and market. Replace the component that was faulted through service information diagnosis. No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.