Semi-Truck Lighting Control Module (LCM) and Headlight Module Repair | UpFix

Why Are My Headlights or Marker Lights Stuck On or Off?

The Lighting Control Module (LCM) regulates power to your truck’s headlights, taillights, and marker lights. When internal relays or circuits fail, lights can stay on constantly, not come on at all, or blow fuses repeatedly.

LCM failures are common in trucks with high electrical demand or exposure to road moisture and vibration.

Common LCM Symptoms

• Headlights or taillights stay on even with key off

• Marker lights flicker or don’t work

• Fuses blowing repeatedly

• Lighting relay clicks but lights won’t power on

Why LCMs Fail

Relays, resistors, and transistor circuits inside the LCM degrade from heat or corrosion. These failures cause power loss or short-circuit behavior.

Repair vs Replacement

Replacing the entire module can be expensive and doesn’t always fix the issue if wiring or CAN logic is damaged. UpFix repairs your original LCM, reinforcing all high-load circuits and verifying every lighting output under real load conditions.

Supported Makes

Freightliner, Kenworth, Peterbilt, Volvo, International and others.

Get your truck back on the road and keep your costs low.
Send your part to UpFix for professional testing and repair.
We’ll restore it to like-new condition, save you up to 80% compared to buying new, and make it plug-and-play ready when returned.