B2587

Diagnostic Chart:

Schematics:

CIRCUIT DESCRIPTION
The body control module (BCM) turns on the automatic lighting control (ALC) parklamp relay when the light sensor senses a dark condition. Battery voltage is supplied to the relay at all times through the PARK LPS fuse. The BCM grounds CKT 1080 in order to activate the relay.

CONDITIONS FOR RUNNING THE DTC
^ The ignition switch is on.
^ The light sensor senses a light condition (ALC parklamps off).

CONDITIONS FOR SETTING THE DTC
CKT 1080 is open or shorted to ground for 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The SERVICE VEHICLE SOON indicator will illuminate.
^ The check gauges chime sounds.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC B2587 will clear when the malfunction is no longer present and the ignition switch is cycled.
^ All BCM history codes will be cleared after 100 ignition cycles (from OFF to ON) with no current codes active during the 100 ignition cycles.

DIAGNOSTIC AIDS
If the DTC is a history DTC, the problem may be intermittent. Try performing the tests while wiggling the wiring and connectors. This can often cause the malfunction to appear.

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
2. Listen for an audible click when the ALC parklamp relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
3. Tests for voltage at the coil side of the ALC parklamp relay. The PARK LPS fuse supplies power to the coil side of the ALC parklamp relay.
4. Verifies that the body control module is providing ground to the ALC parklamp relay.
5. Tests if ground is constantly being applied to the ALC parklamp relay.