Pinpoint Test B: The Rear Fog Lamp Is Inoperative
- Refer to FOG LAMPS
for schematic and connector information.
Normal Operation and Fault Conditions
REFER to: Exterior Lighting - Overview . REFER to: Exterior Lighting - System Operation and Component Description .
DTC Fault Trigger Conditions
DTC Description Fault Trigger Condition BCM B1A79:11 Rear Fog Lamp: Circuit Short To Ground A continuous memory and on-demand DTC that sets when the BCM detects a short to ground from the rear fog lamp output circuit. BCM B1A79:15 Rear Fog Lamp: Circuit Short To Battery Or Open A continuous memory and on-demand DTC that sets when the BCM detects an open or short to voltage from the rear fog lamp output circuit. BCM U1000:00 Solid State Driver Protection Active -Driver Disabled: No Sub Type Information This DTC sets when the BCM has temporarily shut down the output driver. The module has temporarily disabled an output because an excessive current draw exists (such as a short to ground). The BCM cannot enable the output until the cause of the short is corrected, the Diagnostic Trouble Codes (DTCs) have been cleared and a successful self-test is run. For additional information on BCM Field Effect Transistor (FET) protection, REFER to: Module Controlled Functions - System Operation and Component Description . BCM U3000:49 Control Module: Internal Electronic Failure This DTC sets when the BCM has permanently shut down the output driver. The module has permanently disabled an output because an excessive current draw fault (such as a short to ground) has exceeded the limits that the BCM can withstand. CORRECT the cause of the excessive current draw before installing a new BCM. For additional information on BCM Field Effect Transistor (FET) protection, REFER to: Module Controlled Functions - System Operation and Component Description . Possible Sources
- Bulb
- Wiring, terminals or connectors
- Headlamp switch
- BCM
Visual Inspection and Pre-checks
- Inspect the fog lamp bulb and make sure it is OK.
- Inspect the headlamp switch for damage.
- B1 CHECK THE HEADLAMP SWITCH
- Ignition ON.
- Using a diagnostic scan tool, perform the BCM self-test.
Are any headlamp switch module BCM Diagnostic Trouble Codes (DTCs) present?
Yes REFER to: Headlamps . No INSTALL a new headlamp switch. REFER to: Headlamp Switch . TEST the system for normal operation. If the condition returns, GO to B2 - B2 CHECK FOR VOLTAGE TO THE REAR FOG LAMP
- Connect: Headlamp Switch C205.
- Connect: BCM C2280F.
- Disconnect: Rear Fog Lamp C436.
- Ignition ON.
- Place the headlamp switch in the PARKING LAMPS position and engage the rear fog lamp switch.
- Measure:
Positive Lead Measurement / Action Negative Lead C436-1 Ground
Is the voltage greater than 11 volts?
Yes GO to B4 No GO to B3 - B3 REPEAT THE ON-DEMAND SELF-TEST AND CHECK FOR VOLTAGE TO THE REAR FOG LAMP
- 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).
- Measure:
Positive Lead Measurement / Action Negative Lead C436-1 Ground
Is the voltage greater than 11 volts?
Yes INSTALL a new rear fog lamp. No GO to B5 - B4 CHECK FOG LAMP GROUND CIRCUIT FOR AN OPEN
Is the voltage greater than 11 volts?
Yes INSTALL a new rear fog lamp. No REPAIR the circuit. - B5 CHECK FOG LAMP VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO GROUND
- Place the headlamp switch in the OFF position.
- Ignition OFF.
- Disconnect: BCM C2280F.
- Measure:
Positive Lead Measurement / Action Negative Lead C436-1 Ground
Is the resistance greater than 10, 000 ohms?
Yes GO to B6 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, INSTALL a new BCM. Refer to the appropriate Removal and Installation procedure in REMOVAL AND INSTALLATION - B6 CHECK FOG LAMP VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
Is the resistance less than 3 ohms?
Yes GO to B7 No REPAIR the circuit. - B7 CHECK FOR CORRECT BCM (BODY CONTROL MODULE) OPERATION
- Disconnect and inspect all 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, INSTALL a new BCM. Refer to the appropriate Removal and Installation procedure in REMOVAL AND INSTALLATION 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.