Electrical issue

CMOYNIHAN

MEMBER
2015 DODGE RAM
6.7L
6 CYL
TURBO
4WD
AUTOMATIC
58,000 MILES

I have the truck listed above 3500 tradesmen diesel.A few days ago I started having problems with the rear passenger side brake light and turn signal not working. I have a Bradford built flatbed on the back of the truck. The dash will show periodically that the rear brake light is out passenger side deterrent signal on the cluster will flash fast but the turn signal on the passenger side in the front of the truck is blinking normally. The passenger side mirror LED lights are flashing fast with the rear ones are not working at all. The running lights all work on we’re on the truck and this is a intermittent problem that is is existing. I’ve been to the Bradford built dealer in Missouri in my state they check out the truck at the bed and could not find any issues. I’ve had two other mechanics who are unable to find the problem. This is a mystery that I am trying to get to the bottom of. Any help would be appreciated.

Friday, November 20th, 2020 AT 7:17 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,141 POSTS

Hi,

I am looking at the wiring schematics for a cab and chassis. I assume that is how the vehicle was ordered before the flatbed was installed. If that is incorrect, let me know.

Now, what you described is an open circuit. The signal and brake light power from the same source, so it could be a power or ground issue. What really needs to be done is when it is happening, you need to check for power to the white wire with the light green tracer (see pic 1). If there is power, then we know it is likely a ground issue. If that is the case, simply try running a new ground from the light to a known good ground location such as the frame.

The black wire in the pic which is the ground is actually located (mounted) in the engine compartment (driver's side rear of the compartment). Note that the ground for the opposite has a different ground location, so it may be a good idea to check the condition of the ground, make sure it isn't damaged, corroded, or partially broken.

Are you able to check it when the problem is happening? Also, if the body company used a different light assembly than the vehicle came with, open the lens and wiggle the light around to make sure it isn't a bad socket.

Let me know if this helps or if you have other questions.

Take care,
Joe

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