DTC B2578: ALC Headlight Relay Output Short To Battery: Description

DTC B2578 indicates that ALC headlight relay output is shorted to battery. DTC B2578 will set when ambient light sensor indicates bright conditions, ALC option is enabled, ALC headlight output is active and ALC headlight feedback does not exist for one second.

When DTC B2578 is set, ALC headlight relay will turn off and SERVICE VEHICLE SOON indicator will illuminate. DTC B2578 can be cleared when fault state is exited when status of ALC headlights returns to OFF. DTC B2578 can also be cleared using scan tool, or history DTC will disappear after 100 ignition cycles if fault conditions do not reoccur.

DTC B2578 indicates that ALC headlight relay output is shorted to battery. DTC B2578 will set when ambient light sensor indicates bright conditions, ALC option is enabled, ALC headlight output is active and ALC headlight feedback does not exist for one second.

When DTC B2578 is set, ALC headlight relay will turn off and SERVICE VEHICLE SOON indicator will illuminate. DTC B2578 can be cleared when fault state is exited when status of ALC headlights returns to OFF. DTC B2578 can also be cleared using scan tool, or history DTC will disappear after 100 ignition cycles if fault conditions do not reoccur.