B2418

DTC B2418 Daytime Running Lamps (DRL) Control Module Circuit:

DTC B2418 Daytime Running Lamps (DRL) Control Module Circuit (Part 1 Of 2):

DTC B2418 Daytime Running Lamps (DRL) Control Module Circuit (Part 2 Of 2):

CIRCUIT DESCRIPTION
The Body Control Module (BCM) provides interface to the Daytime Running Lamps (DRL) control module allowing the BCM to determine current ambient light operation mode. The BCM communicates this information by the Class II serial data link to the instrument panel cluster. This circuit also allows the BCM to energize the headlamps for the twilight sentinel feature.

The BCM enters the twilight sentinel mode (by grounding circuit 1970 causing the headlamps to turn on) if the ignition is turned to the OFF position while:
^ The headlamps switch is in the off position.
^ The headlamps are on due to night mode of the auto headlamp control.

If a short to voltage occurs while the BCM is in the twilight sentinel mode, a fault condition is present and a DTC will set.

CONDITIONS FOR SETTING THE DTC
^ The BCM detects that a short to voltage has occurred in circuit 1970 ONLY when the twilight sentinel mode is active.

ACTION TAKEN WHEN THE DTC SETS
^ Stores a DTC B2418 in the BCM memory.
^ No driver warning message will he displayed for this DTC.
^ The BCM turns off its output to the DRL module.

CONDITIONS FOR CLEARING THE DTC
^ When the ignition switch is rotated from the OFF position to the RUN position, a current DTC B2418 is always cleared. If the short to voltage in circuit 1970 is still present when the BCM attempts to ground circuit 1970 to enter the twilight sentinel mode, DTC B2418 will NOT reset as a current DTC.
^ A history DTC will clear after 100 consecutive ignition cycles if the condition for the fault is no longer present.
^ Using a scan tool.

DIAGNOSTIC AIDS
^ The BCM sets DTC B2418 as a current DTC only if the short to battery occurs while the BCM is in the twilight sentinel mode.
^ Check fuses for a possible open fuse, indicating that the circuit(s) protected by such fuse is contacting circuit 1970.
^ The following conditions may cause an intermittent malfunction to occur.
- BCM shorted to voltage internally.
- An intermittent short to voltage in circuit 1970.
- DRL control module shorted to voltage internally.
^ If the DTC is a history DTC, the problem may be intermittent. Try performing the tests shown while wiggling wiring and connectors, this can often cause the malfunction to appear.
^ DTC P1626 will set in the Powertrain Control Module (PCM) when the ignition switch is in the RUN position with the BCM disconnected.

TEST DESCRIPTION
Numbers below refer to the step numbers on the diagnostic table.
1. Always perform the BCM Diagnostic System Check before attempting to diagnose a DTC B2418.
2. Checks for a short to B+ in circuit 1970.
3. Determines if there is a short to B+ in circuit 1970 or the BCM.
6. Checks BCM connector C2 for possible short to B+.