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2018 Ram Promaster 3500 High Top Extended Extended
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Discussion Starter · #1 · (Edited)
My factory trailer tow package on my 2018 Ram Promaster 3500 Extended has issues with the left turn signal/brake lights. (Brown & yellow wire). All my lights on the van work fine, I've read all the threads regarding similar issues on this forum. I unplugged the trailer control module in the driver's side rear corner panel. Checked and replaced the small 20 amp fuse on the long pigtail in battery box. Never did blow. My trailer lights are fine because I hooked it up to both of my Dodge Durango's and all lights work. I've called 2 Promaster dealers close to me in South Georgia. Both service advisors said they are clueless because they never sold a Promaster with a tow package. I ordered the van with it, plus many more upgrades. The odd thing is now when I plug the 4 prong tester in the 4 pin and also I used a 7 to 4 pin reducer to check both. All the lights work on the tester. Both blinkers and brakes. Driving lights too. So, I purchased a set of temporary magnet lights from Lowe's and plugged them in, no left blinker or left brake light. I plugged the temporary lights into the Durango's and it works as it should. The dealers told me to drive the 1-1/2 hours and I may possibly have to leave it if they have to order something. Really don't like that idea since I've did a van conversion. Don't won't a technician messing around with the complex of wiring for my solar, 110 and 12volt wiring that all converges in the garage under the bed close to the area they would be working. I know about the recall on the 2016 TCM, but my number 68229650AD appears to be the one they used for the recall. Any thoughts from my fellow Promaster owners?
 

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My factory trailer tow package on my 2018 Ram Promaster 3500 Extended has issues with the left turn signal/brake lights. (Brown & yellow wire). All my lights on the van work fine, I've read all the threads regarding similar issues on this forum. I unplugged the trailer control module in the driver's side rear corner panel. Checked and replaced the small 20 amp fuse on the long pigtail in battery box. Never did blow. My trailer lights are fine because I hooked it up to both of my Dodge Durango's and all lights work. I've called 2 Promaster dealers close to me in South Georgia. Both service advisors said they are clueless because they never sold a Promaster with a tow package. I ordered the van with it, plus many more upgrades. The odd thing is now when I plug the 4 prong tester in the 4 pin and also I used a 7 to 4 pin reducer to check both. All the lights work on the tester. Both blinkers and brakes. Driving lights too. So, I purchased a set of temporary magnet lights from Lowe's and plugged them in, no left blinker or left brake light. I plugged the temporary lights into the Durango's and it works as it should. The dealers told me to drive the 1-1/2 hours and I may possibly have to leave it if they have to order something. Really don't like that idea since I've did a van conversion. Don't won't a technician messing around with the complex of wiring for my solar, 110 and 12volt wiring that all converges in the garage under the bed close to the area they would be working. I know about the recall on the 2016 TCM, but my number 68229650AD appears to be the one they used for the recall. Any thoughts from my fellow Promaster owners?
I seems to have the same problem on my van, left blinker will sometime blink a few time then stop, sometime it won't work at. Same as left brake light, sometime it work sometime it don't. I probed voltage directly from the 4 and 7 pin hitch connector and neither lit up my test light when probing left turn signal terminal (right blinker work flawlessly every time). Lights on the van itself all works without issues. Beside replacing the trailer tow module (68379832AA) I'm pretty much at a lost.
 

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After more testing it seems I am getting constant 12v on both side while applying the brake but as soon as I put a load on the left side trailer brake light (ex: a filament bulb test light) the voltage drop to around 2v. If I do the same thing on the right side the voltage stay constant and the filament bulb light up.
 

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2018 Ram Promaster 3500 High Top Extended Extended
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Discussion Starter · #4 ·
After more testing it seems I am getting constant 12v on both side while applying the brake but as soon as I put a load on the left side trailer brake light (ex: a filament bulb test light) the voltage drop to around 2v. If I do the same thing on the right side the voltage stay constant and the filament bulb light up.
Finally figured it out and 100% fixed... I had to replace the control module located in the rear driver side pillar behind the plastic vent. The model number that was in my 2018 Ram Promaster wasn't the same as the earlier recall number. So, that made me think my module wasn't the problem. Well...after troubleshooting everything else I decided to have the Ram Promaster dealership order me a new one. I took the one out of my van (it just has double sided tape holding it in place) and showed it to the parts guy. He looked the number up and advised me that the one that shows up on his computer is a different model number. I was thinking this may be a good thing. He ordered it for me under warranty and shipped it to me a week later. Took me 5 minutes to reinstall the new one. Now all my trailer lights works great. I'll attach a picture of the one that was bad. I don't have a picture of the new one
But, just make sure to not get the one I'm sending you. It's a 2017 module that apparently isn't any good. Good luck!

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Finally figured it out and 100% fixed... I had to replace the control module located in the rear driver side pillar behind the plastic vent. The model number that was in my 2018 Ram Promaster wasn't the same as the earlier recall number. So, that made me think my module wasn't the problem. Well...after troubleshooting everything else I decided to have the Ram Promaster dealership order me a new one. I took the one out of my van (it just has double sided tape holding it in place) and showed it to the parts guy. He looked the number up and advised me that the one that shows up on his computer is a different model number. I was thinking this may be a good thing. He ordered it for me under warranty and shipped it to me a week later. Took me 5 minutes to reinstall the new one. Now all my trailer lights works great. I'll attach a picture of the one that was bad. I don't have a picture of the new one
But, just make sure to not get the one I'm sending you. It's a 2017 module that apparently isn't any good. Good luck!

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Thanks, I had an inch the problem would be the trailer tow module. I will try replacing it and report back. And you are right there is a new revision for that part which was replaced by #68379832AA
 

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2015 Winnebago Travato 59k on Promaster 3500
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Entirely different problem but couldn't see a way to send a message to Vansibel so will hope you see this post. I read thru your LED replacement post but couldn't see if you had replaced the dash light. I can't see my dash properly during daylight running and have been leaving my headlights on which burns out the headlights. I would like to know if it is reasonably easy to change the dash lights for a brighter LED. I am guessing that the dimming mechanism which exists won't work for an LED bulb. Thanks
 

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2018 Ram Promaster 3500 High Top Extended Extended
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Discussion Starter · #9 ·
Entirely different problem but couldn't see a way to send a message to Vansibel so will hope you see this post. I read thru your LED replacement post but couldn't see if you had replaced the dash light. I can't see my dash properly during daylight running and have been leaving my headlights on which burns out the headlights. I would like to know if it is reasonably easy to change the dash lights for a brighter LED. I am guessing that the dimming mechanism which exists won't work for an LED bulb. Thanks
I'm at a lost on your dash lights not being bright enough. Thankfully I haven't had this problem with my 2018 Promaster. Hopefully Vansibel will see this conversation. Good luck!
 

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Entirely different problem but couldn't see a way to send a message to Vansibel so will hope you see this post. I read thru your LED replacement post but couldn't see if you had replaced the dash light. I can't see my dash properly during daylight running and have been leaving my headlights on which burns out the headlights. I would like to know if it is reasonably easy to change the dash lights for a brighter LED. I am guessing that the dimming mechanism which exists won't work for an LED bulb. Thanks
By dash light you mean tachometer ? No I didn't changed those since I didn't saw any reason why, my dash light seems sufficient.
 

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Look like I spoke too soon... while changing the tow module seems to have resolved the issue while I was testing the left signal with a filament bulb, it look like the problem is back... Not sure if it's the tow module again but that would be quite the coincidence. Problem might be elsewhere but for now I'm at a lost and not in a rush to dissasemble the RV panel yet again. Any input is welcome at this point.
 

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Removed the panels and tested the current directly at the module and the 12v out for the trailer left light was not getting anything so I knew it was not the wiring. Brought the car to the dealer under warranty and they confirmed it was again the tow module... which they replaced and the problem went away.
 

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This post helped me alot. Thank you! I was pulling my hair out trying to figure out this left trailer light problem. It was very confusing because it only happens under load so a multimeter or trailer test tool wasn't helpful. I have a 2019 Ram Promaster 3500. When I replaced the trailer light module, the old module was dated 2017 model "68229650AD". The new one was dated 2020 model "68379832AA" and it solved the problem. Why they would put in a 2017 module into a 2019 van when there is a recall on the part is beyond me. Again, thank you for posting your experiences on this issue.
 

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Removed the panels and tested the current directly at the module and the 12v out for the trailer left light was not getting anything so I knew it was not the wiring. Brought the car to the dealer under warranty and they confirmed it was again the tow module... which they replaced and the problem went away.
The dealer tech who worked on my tow module went thru 7 modules before he found a good one. Failed 3 weeks later. Had to wait for the recall part revision to be available but you could disconnect/reconnect and trick the module temporarily.
 
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