Diagnose and fix no Headlights Dodge Vehicle
A no headlight Dodge condition can be caused by many things, from a bad
turn/headlight switch to bad body control module (BCM), front control module (VCM) or even a bad integrated (IPM) or totally integrated power module (TIPM). The wiring may seem complicated but it’s pretty common among most late model cars.
How Dodge headlights get power
In the old days you’d operate the headlight switch and the switch itself would supply power to the headlights. That’s not how it works in a late model vehicle. The headlight switch only acts as a signal to tell the body control module that the driver is requesting headlights.
In the Chrysler system, the headlight switch is built with several resistors. The BCM supplies power to the headlight switch. Depending on whether the driver chooses parking lights, headlights or high beams, the power flows through one or more resistors, and that reduces the voltage. The BCM reads the voltage and based on what it sees, it interprets the voltage as the command for parking, low beams or high beams. The BCM then sends a DIGITAL signal to the FCM located in the IPM or TIPM (depending on the year of the vehicle). It’s the FCM that actually switches power.
What is an FCM?
Think of the front control module as an electronic relay that’s capable of switching
power on and offer to multiple items. It knows when to operate based on a digital signal sent from the BCM to the IPM or TIPM. The transistorized unit can fail, and when it does, it fails to provide power.
What causes a no headlights Dodge condition?
If you can’t turn on your low or high beams, your first job is to test for power and ground at the headlight connector (see wiring diagram below). As you can see, the FCM and IPM or TIPM provides power AND ground to the headlights. If you see headlight power but no ground, welcome to the club. Chrysler had done a great (NOT) with the ground for the headlights. It’s the G300 ground point and it’s located on the left (driver’s side) “B” pillar. The B pillar is behind the driver’s seat (windshield is the A pillar).
Shops report a VERY high incidence of LOOSE or corroded G300 ground straps. To access the G300 ground, remove the plastic trim. Then check the ground for corrosion or looseness. If corroded, clean off the corrosion, apply a light film of dielectric grease to the steel and eye ring. Then resecure. If loose, tighten firmly. Then try the headlights. If that works, you’ll have corrected the problem.
©, 2018 Rick MuscoplatPosted on by Rick Muscoplat