Driver Side Running Board Light Low Voltage (1 Viewer)

[baggar11]

Driver side running board light has been out for a while. Decided to pop a new bulb in there and noticed the new led fainting comes on, flickers and then shuts off. Tried with a halogen and the bulb gets a little warm. Tried passenger side with both bulbs and no issues.

Multi meter showed that the driver side was seeing about 1.6-2.5 volts, while the passenger side was right around 12 volts. Anyone run across this before? Any idea for troubleshooting? I did pop the bulb base out of the socket and measured directly there and same story. Not sure where the rest of the wire ends up running up towards the front of the vehicle.

 

[doru]

Probably the wire got damager along the way to the running board. I suggest tracking it and see where the damage is.

 

[daneo]

The part that throws me for a loop is that the voltage is low when there’s no bulb present. If there were damage to the wire or corrosion on a connection causing high resistance, I would expect the voltage to still be ~12V when there’s no load.

Is the stock bulb halogen? Were you running LEDs when it died?

 

[lx200inAR]

Those lights are on a dimmer circuit aren’t they? As in they start by brightening from dim, then sit fully lit, and then dim down slowly. Are you sure you are measuring when they should be fully lit? I’d be looking for the module (probably the “body control module”) that controls the dimming.

 

[baggar11]

Is the stock bulb halogen? Were you running LEDs when it died?

Yes, the stock bulb is halogen. I swapped out the dead on arrival halogens for LEDs soon after we bought the rig. Always had problems with the LEDs, as they would flicker. Then the driver side went out completely. I bought some new LEDs off amazon that had good reviews for being able to dim. That's when I found the low voltage issue.

Are you sure you are measuring when they should be fully lit? I’d be looking for the module (probably the “body control module”) that controls the dimming.

The dimming cycle only lasts a second or two. Passenger side works fine and gets up to 12 volts after the dimming delay period ends. Driver side just never goes past 2.5 volts or so though. Any idea where the dimming module is?

 

[bloc]

So these actually seem to be controlled by the "Multiplex Network Body ECU" not the main body control module. It's Module L33 in the rear driver's side of the truck. Then through the KL2 connector back there to the main body harness (pink on the following diagrams), then through the kg1 connector down to the running board.

All in all not a very complicated wiring route, but digging those connectors out of the rear quarter won't be fun.

One option would be to try swapping pins with the passenger side wire at L33 (the wire from pin 9 goes to position 8) and see whether the problem persists. And vice versa.