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Discussion Starter #1
Hey everyone, need some help here. I was trying to attach a tow dolly to my van with a 4 pin connector, but the right blinker didn’t seem to be registering on the trailer wiring. The right blinker on the van itself works fine. Took it to the Dodge dealership after having no such luck with local guys. At first they thought it was a fuse, but now they’re saying that the Body Control Module is “fried”. More than $1k to replace and the part would take 4 days to arrive (we’re currently stranded and unable to tow in Fort Stockton, TX). I couldn’t stomach the cost right now, but now I’m out $170 bucks for a diagnostic fee. Anyone have any BCM issues like this where everything else seems to work fine? Or is this a little suspicious? Thanks.
 

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2014-159 HR in CT
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Seems suspicious to me, but the BCM does control almost everything in the van.

OTOH, you could use a generic trailer cable as long as it has a solid state adapter or relay to insure no additional load on the taillight circuit. You connect the wires to the rear wires in the back corners of the van right behind the lights.

Can't drive without the signal lights? The trailer running lights and brake lights work, right?
 

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Discussion Starter #3
Seems suspicious to me, but the BCM does control almost everything in the van.

OTOH, you could use a generic trailer cable as long as it has a solid state adapter or relay to insure no additional load on the taillight circuit. You connect the wires to the rear wires in the back corners of the van right behind the lights.

Can't drive without the signal lights? The trailer running lights and brake lights work, right?
It didn’t feel right, but my power locks fuse F38 has been out a few times, so idk. U-Haul wouldn’t let me rent a tow dolly unless it passed the inspection on lights, so without that blinking right turn signal I was out of luck.
 

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'16 2500 159 HT Granite Window - OH(io)
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Just curious. Do you have the factory 4-way connector, or it it an aftermarket add-on? The reason that I ask is the Promaster has separate circuits for turn signals and brake lights. The OEM system combines these signals via a module to provide the trailer lights the signals on a single wire. One for right, one for left. The module has been known to fail.
 

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2016 136WB low roof diesel, converted to an RV by Sportsmobile, TX
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I don't know if I would suspect the BCM if the van's lights are working, but the trailer connection is not. IIRC, there is a separate module that handles the trailer lights; perhaps that is at fault rather than the main BCM.
 

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Discussion Starter #6
It seems to be factory, on the trailer input I have both the 4 pin and 7 pin connection points. Also, there’s a ton of conduit and well wrapped wires in the rear left/right columns along with a little black box (the converter box?) on the left side that everything is routed through. I’m curious if a converter box replacement might do the trick, but now I’m pretty skittish about altering anything with those wires after being told my BCM is “fried” by a Ram dealership.
 

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'16 2500 159 HT Granite Window - OH(io)
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That little black box is the converter box. When my trailer lights did not work on my 2016, that was the cause. However, I did not have any lights at all.
 

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2017 2500 HiTop 159 Cargo Van white.
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Have you tried using the 7 pin connector? Probe the contacts in the 7 pin.
 

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Discussion Starter #9
If I recall correctly, we tried a 4 pin adapter for the 7 pin and it was the same issue. I'll get a probe and inspect it again though. I know the u-haul trailers were really basic and only required 4 pin.
 

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2016 3500 ext-ht
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Hey everyone, need some help here. I was trying to attach a tow dolly to my van with a 4 pin connector, but the right blinker didn’t seem to be registering on the trailer wiring. The right blinker on the van itself works fine. Took it to the Dodge dealership after having no such luck with local guys. At first they thought it was a fuse, but now they’re saying that the Body Control Module is “fried”. More than $1k to replace and the part would take 4 days to arrive (we’re currently stranded and unable to tow in Fort Stockton, TX). I couldn’t stomach the cost right now, but now I’m out $170 bucks for a diagnostic fee. Anyone have any BCM issues like this where everything else seems to work fine? Or is this a little suspicious? Thanks.
Check your vin for factory towing module recall before installing a new BCM.
 

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'16 2500 159 HT Granite Window - OH(io)
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Check your vin for factory towing module recall before installing a new BCM.
My 2016 was never on the recall list, but since the van was only a week old when I discovered the problem, the module was replaced under warranty.
 

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2019, 159", High Roof, 2500
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I was just going to ask .. factory tow wiring has a “computer module” that is added. IF the van light works but not the trailer then I’d doubt it’s the BCM. BCM seems to be a common part RAM throws at undiagnosed electric issues.

If factory wiring

check 7 pin connector

check tow harness where it plugs into light connectors (it plugs inline where the rear lights are)

factory tow hitch wiring install directions are here

IF not factory check a site like etrailer and they will have similar wiring directions as most still connect inline with brake lights then have a little “module” box.

if all connections good and only one light out on trailer connector I’d put $ on the trailer light module.
 
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