B2640

B2640 - Delayed Exterior Lighting Control Circuit Malfunction

Schematic:

CIRCUIT DESCRIPTION
The body control module (BCM) monitors circuit 1138 from the solar light sensor to determine if the automatic headlamp system requires activation. If signal circuit 1138 is above the 4.75 volts the BCM will fail this DTC as current. The default for this failure is the automatic headlamp system will turn On the exterior lighting system including the headlamps and parklamps.

DTC PARAMETERS
^ Sensor input greater than 4.75 volts.
^ Ignition is in RUN.
^ Condition is present for 5 seconds.
^ No telltale illumination.
^ Default to all exterior lights On.

DIAGNOSTIC AIDS
^ Check for poor connection at the BCM. Inspect harness connectors for backed-out terminals, improper terminal mating broken connector locks, improperly formed or damaged terminals and poor terminal-to-wire connection (terminal crimped over wire insulation and not conductors).
^ Inspect wiring harness for damage. Check for broken or chaffed insulation.
^ If fault is suspected to be intermittent, wiggling harness wiring may help in locating fault.
^ Dark condition exists if sensor input is above 4.1 volts for 15 seconds.
^ Daylight condition is sensor input is below 3.5 volts for 30 seconds.
^ Input to BCM.

TEST

Diagnostic Chart: