Trailer brake warning/controller problems… help?

[boatmanea]

While towing on a long (3 week) RV trip I have been having multiple issues… This is a long post, but I am wondering if these are interconnected or just sh*t-luck.

I have a 2017 Ram 3500 Laramie Longhorn mega-cab short-bed DRW with factory installed electronic brake controller and heavy-duty tow suspension with about 97,000 miles. I am pulling a 2021 Grand Design ST3740BH-R 5th-wheel using a Pull-rite auto-slider hitch. NO previous issues with this on a similar 8,000 mile cross-country trip last year.

About 3 days into our 2022 cross-country trip, I started having an intermittent messages alternating between “check trailer brake wiring” and “trailer brake disconnected.” This cycled about 3 or 4 times before staying on. I had NO trailer brakes at this point with my brake pedal or manually. I got off at the next exit and parked at a truck stop. Truck off and restart without any change. I rechecked the plug in the bed and on the bumper, cleaned the blades, bent them to make better contact - same message. Checked my voltage at the bed and bumper and at the junction box where the pig-tail plugs in - all good. Crawled under the RV and check all the connections I could get to and the wire that I could see - all good. All the lights worked, just no brakes. Managed to find a mobile-tech ran some diagnostics and told us it was the truck (without looking at the trailer?!?) Took it to a dealer the next day who did a full diagnostic and told us it was the trailer. Took it to a trailer repair shop who found a loose magnet wire that had been crimped between the magnet and the brake drum. Bingo. Problem solved and we were back underway…

1 day later got the dreaded “service DEF In 150 miles” message. Managed to find a mobile-tech and a dealer who had the parts in stock (DEF pump and heater went bad) and after about 5 hours, we were back underway…

Now about a week later, we start having the same intermittent messages alternating between “check trailer brake wiring” and “trailer brake disconnected.” It kept flashing on and off for varying lengths of time and without any relation to bumps in the road or slope and sometimes would go away completely for an hour or a few minutes. Again, no brakes on the trailer. We were close enough to the campsite and limped into camp. Seemed like the same issue and I figured it was a bad brake wire someplace. I have no capacity to pull wheels and drums to check inside, so I do what I can on the road on a Sunday. Went to Lowes and bought some wire and crimps and replaced the interconnecting wire that runs through both axles. Then the trailer disconnected warning went away. Problem solved? Not for long…

The next day we were about 200 feet out of the campsite and the warnings begin. I get the “check trailer brake wiring” but no disconnect warning. I had trailer brakes, but only with the manual control, so I thought we’d be ok to continue traveling. Of course, it’s a holiday, so no one is available to help anyway. Unfortunately, now I noticed I had a “check engine” light on. Engine running fine and towing like the beast it is, no shudders, hiccups, or anything. Scrolling through the saved messages, I only have the two “check trailer brake wiring” and “trailer brake disconnected” messages and nothing about servicing the engine. Turn the truck off and on, no change. Still have brakes manually and it’s July 4th, so we roll on. About half-way to our next camp site, the red icon for trailer brakes just disappears and I have brakes again with the pedal. At this point the saved messages are blank, but I still have a check engine light. After we get to our campsite and restart the truck after checking in, I have no warnings, no warning lights, and no saved messages - everything seems to be functioning normally.

So, the main question I have is, what the heck is going on with my trailer brakes? Is it the brake controller module going bad? How can I prove that the controller is bad when everything is functioning normally? Would a bad brake controller somehow also trigger a check engine light with no message? Was there even an engine issue or was this just an electrical glitch? Should I take it to the dealer again? They should be able to find the codes, but is this going to just point back to the trailer (which I don’t think is the issue at all since I have trailer brakes and everything is functioning normally.) Or, now that everything has gone away, should I just keep going? Thoughts?

 

[2003F350]

Okay I got through that post...you're right it was long but you had a LOT of detail you needed to get out there. Well done.

The easiest way to tell if it's the truck or the trailer is to hook the trailer to a different truck and/or hook the truck to a different trailer (I know, not the easiest when you're on the road - good luck finding someone willing though some RVers are okay with helping each other out) and take them for a ride to see what comes up.

For the trailer brake issue...it wouldn't surprise me if you've still got some bad wiring or a bad connection somewhere around the brakes on the trailer. Grand Designs are good units, but in the post-covid world the entire RV industry is having issues with build quality. There has also been a push for 'environmentally friendly' wire coverings...that smell good to rodents. So it is POSSIBLE that you have a chewed wire somewhere as well. Because they've moved a lot of the wiring to the inside of the coach, that could be a devil to track down. Since the warning went away and you got all braking back, I would 100% lean toward a loose or bad connection - I fought that issue all last summer on my flatbed. In my case the plug wasn't making a good connection but it was a cheap plug, not a more expensive one like on our camper.

For your check engine light, a lot of times that doesn't store a message in your DIC - you need to have that code pulled, either by a dealer or at an auto parts store with a code reader. Without knowing what that code is, we can't do any diagnosis really, especially if the truck is running correctly. It's entirely possible that it was a 'soft code,' meaning whatever triggered it was an anomaly and has since resolved itself, turning the light off. The code SHOULD still be stored though.

 

[tankertec]

sorry to hear about your problems when out to enjoy a trip. we did 4000 mile trip june 21 and had no issues at all with truck or tailer. point on reply, yes probably wiring issue with brake system. loose grounds or no ground can cause lots of weird issues. had issue with sisters car that everything in the dash ,radio,a/c fan ,wipers all turned on and off with blink of turn signals. ground on rubber mounted steering collum to dash broken. with codes know mine will throw a soft code for 0.1 volt difference between battery voltage and pcm ,ecm . just dealt with ignition win node replacement which was causing alot of issues starting and staying running which was hopefully causing all the 0.1 differences. we will see. use ohm meter to check grounds so if high resistance you know theres a problem. had trailer with battery ground through metal frame and wood of floor. wood dries out and ground got loose. hope you get it fixed up.

 

[18CrewDually]

Other than plug, the second most common issue I see are magnet wire connections at the backing plate and axle. Usually they are a crimped connector that allows moisture and corrosion causing a poor connection ending in the copper wire strands over heated and brittle making no connection. The last trailer I worked on had this issue on both front and rear axles on the driverside resulting in the brake controller NOT recognizing a trailer being hooked up so it had no brakes. Magnets were fine. I stripped back to good clean wire and they all work fine.