Pinpoint Test D : Both Rear Fog Lamps Are Inoperative
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.
- D1 CHECK THE HEADLAMP SWITCH
- Ignition OFF.
- Disconnect: Headlamp Switch C205 .
- Carry out the headlamp switch component test. Refer to Wiring Diagram Component Testing for schematic and connector information.
Does the headlamp switch pass the component test?
Yes GO to D2 No INSTALL a new headlamp switch. REFER to: Headlamp Switch . - D2 CHECK THE BCM (BODY CONTROL MODULE) REAR FOG LAMP SWITCH INPUT CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: BCM C2280B .
Is the resistance less than 3 ohms?
Yes GO to D3 No REPAIR the circuit. - D3 CHECK FOR VOLTAGE TO THE REAR FOG LAMPS
- Ignition OFF.
- Connect: BCM C2280B .
- Disconnect: LH Rear Fog Lamp C437 .
- Ignition ON.
- Place the headlamp switch in the PARKLAMPS position and engage the rear fog lamp switch.
- Measure:
Positive Lead Measurement / Action Negative Lead C437-1 Ground
Is the voltage greater than 11 volts?
Yes REPAIR the rear fog lamps ground circuit for an open. No GO to D4 - D4 REPEAT THE ON-DEMAND SELF-TEST AND CHECK FOR VOLTAGE TO THE REAR FOG LAMPS
- Place the headlamp switch in the OFF position.
- Using a diagnostic scan tool, perform the BCM self-test.
- Clear the Diagnostic Trouble Codes (DTCs) and repeat the self-test (required to enable the lamp output driver if DTC U1000:00 is present).
- Ignition OFF.
- Ignition ON.
- Place the headlamp switch in the PARKLAMPS position and engage the rear fog lamp switch.
- Measure:
Positive Lead Measurement / Action Negative Lead C437-1 Ground
Is the voltage greater than 11 volts?
Yes INSTALL a new LH rear fog lamp. REFER to: Rear Fog Lamp . No GO to D5 - D5 REPEAT THE ON-DEMAND SELF-TEST AND CHECK FOR VOLTAGE TO THE REAR FOG LAMPS WITH RH (RIGHT-HAND) REAR FOG LAMP DISCONNECTED
- Place the headlamp switch in the OFF position.
- Ignition OFF.
- Ignition ON.
- Disconnect: RH Rear Fog Lamp C436 .
- Using a diagnostic scan tool, perform the BCM self-test.
- Clear the Diagnostic Trouble Codes (DTCs) and repeat the self-test (required to enable the lamp output driver if DTC U1000:00 is present).
- Ignition OFF.
- Ignition ON.
- Place the headlamp switch in the PARKLAMPS position and engage the rear fog lamp switch.
- Measure:
Positive Lead Measurement / Action Negative Lead C437-1 Ground
Is the voltage greater than 11 volts?
Yes INSTALL a new RH rear fog lamp. REFER to: Rear Fog Lamp . No GO to D6 - D6 CHECK THE REAR FOG LAMP VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO GROUND
- Place the headlamp switch in the OFF position.
- Ignition OFF.
- Disconnect: BCM C2280C .
- Measure:
Positive Lead Measurement / Action Negative Lead C437-1 Ground
Is the resistance greater than 10, 000 ohms?
Yes GO to D7 No REPAIR the circuit. After the repair:If no Diagnostic Trouble Codes (DTCs) are present, TEST the system for normal operation. If DTC U1000:00 is present, CLEAR the Diagnostic Trouble Codes (DTCs) and REPEAT the self-test (required to enable the lamp output driver if DTC U1000:00 is present). If DTC U3000:49 is present, BCM guided routine is not applicable for this vehicle and market. Replace the component that was faulted through service information diagnosis. - D7 CHECK THE REAR FOG LAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
Is the resistance less than 3 ohms?
Yes GO to D8 No REPAIR the circuit. - D8 CHECK FOR CORRECT BCM (BODY CONTROL MODULE) OPERATION
- Disconnect and inspect all BCM and all related in-line 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 and all related in-line 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 module connections. ADDRESS the root cause of any connector or pin issues.