DRL Disable Procedure - keywords daytime disable headlights headlamps lamp light

This PI was superseded to update model years and Recommendation/Instructions. Please discard PIT4328.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

**** THIS INFORMATION APPLIES TO U.S. VEHICLES ONLY ****

All requests for Daytime Running Lamps (DRL) disable are to be referred to Techline Customer Support Center (TCSC). Instruction about vehicle qualifications and requirements for DRL disable will be provided by TCSC. TCSC is GM's central record keeping location for all of these requests. TCSC toll free number is 1-800 828-6860.

**** THIS INFORMATION APPLIES TO U.S. VEHICLES ONLY ****

Requests for DRL/auto headlamp disconnects must be made by appropriate agencies. The vehicle in question must be owned by a law enforcement agency, military agency or security company. (City/State, Sheriff, FBI, CIA, DEA, Emergency Vehicles.Etc.) It is recommended the dealership obtain a letter on the agencies letterhead requesting the DRLS/auto headlamps be disabled. The letter should contain the specific vehicle identification number which will be disabled, and a statement which reads, "the DRL/auto headlamp system will be made fully operational prior to disposal/sale of the vehicle." the letter should be kept in the vehicle service file at the dealership.

Procedures to disable daytime running lamps (DRL):

Have the dealership technician call Techline at 1-800-828-6860 and request a new calibration for the truck body control module (tbcm) that will disable the DRL's. Recalibrate the TBCM with the new calibration.

Procedures to disable to auto headlamps:

Unplug the ambient light sensor and put a 600 ohm resistor in place of the sensor. The resistor will command the TBCM to turn the auto headlamps off. The headlights will now have to be manually turned on with the headlight switch.

Secure the resistor and connector to prevent rattles.etc.

Note: Vehicles equipped with Automatic HVAC (RPO CJ2) may have a light sensor that also includes the sunload sensor for the HVAC system. Make sure the resistor is wired into the ambient light sensor signal wire (Circuit 278) and ground (Circuit 1851). This can be achieved by backing out pin 2 at the light sensor and removing the terminal and adding the resistor to the wire and then splicing the other end of the resistor to the ground wire 2 inches from the light sensor.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.