RAM Trailer Brake Controller Operation and Trouble-Shooting

[Steven@147]

Every once in a while we get the CTBW "Check Trailer Brake Wiring" message or TBD "Trailer Brake Disconnected" warning.

When we left Tucson this spring we got the warning message on the truck after a hard stop and it took a long time for us to get it cleared. I had thought it was just the 7 way plug but now I'm not so sure. I don't want it to happen again at a bad time with no RV brakes. I've read on the forum a lot of owners have had this problem and found frayed or shorted wires inside the axle tubes or found undersized wires. I'm in the process of planning to remove and replace the RV brake wires running through the axle tubes. Some have replaced the brake wires with a larger 10 gage wire.

I found a really good conversation on a RAM HD forum explaining how the RAM Integrated Trailer Brake Control Module works, in conjunction with speed, truck brake pedal or trailer brake manual selector, something I haven't seen before. The conversation also explains how at speeds below 20 MPH, trailer braking is reduced by the Brake Controller. It's a real good write up and backed up by OBDII data placed in charts and graphs. Also explains the differences between "Light and Heavy Electrical", Light and Heavy Electrical over Hydraulic selections and what it does to the trailer brake controller output.
Read here - https://hdrams.com/forum/index.php?threads/brake-controller-troubleshooting-technical-info.6004/

For me, I believe the information is factual, I did a selected copy and paste from the RAM HD forum and printed it out and inserted it into the truck owners manual. The owners manual doesn't give you much info at all about how the truck trailer brake systems works.

Thought I would share the info I found. When I get my brake wires removed and replaced I'll tell you the results of what I found.

 

[dryfly]

An article appeared this morning on Mike Sokol's RV Electricity regarding similar problem with 2024 GM brakes. It came to me in his daily email so I can't link it. Basically stated it had to do with issue of truck communicating with trailer battery voltage through the 7 pin connector, and getting a voltage error.

 

[Hoopy Frood]

My understanding about the brake wiring, is that one should have individual 12 gauge wire from a junction box to each wheel/brake. I think most of the OEM wire is 14 gauge, and if it's 12 gauge, it's daisy chained together so you may not get maximum voltage to each brake. I believe for 12" brakes, the maximum amperage draw will be around 4 amps, so if the brakes are daisy chained, you'd be drawing 16 amps along the length of that wire. I've always meant to check mine to see what the amps are, but just haven't done it yet. Supposedly some people have wired each wheel independently and noticed a big difference in braking ability. But that's strictly apocryphal, so YMMV.

 

[Steven@147]

Well I think I found our problem. We had a nice day today and so I spent all afternoon replacing the brake wiring on our axles. The front axle had two places of frayed wire and the rear axle had one area that was bad inside the axle tube part of the way down the tube and the OEM wire is double insulated. Anyone of these bad places in the wire touching the axle tube and it would give us a short in the brake wiring and the problem we were experiencing. It was intermittent at first and progressively got worse. When we left Tucson this spring I didn't think I was going to get the error to go away and then it was ok all the way to Indiana.
Installed new 12 gage wire, sealed splices, encased in convoluted tubing and tie strapped to the back side of the axles. Yeah the rest of the brake wiring seems to be 14 gage wire. Well anyway got the bad places fixed so we should be good to go now.

 

[Hoopy Frood]

Did you notice any change in the braking force with the change to 12 gauge wire, and rewiring?

 

[Steven@147]

Did you notice any change in the braking force with the change to 12 gauge wire, and rewiring?

Hello Howard. I haven't towed it yet just got it done this afternoon but I doubt it will make that much of a difference in braking force. If I had also replaced the 14 gage wire from the junction box all the way to the the axels with 12 gage, probably would notice an improvement.

Now I'm slow grilling T-Bones for supper.

 

[Hoopy Frood]

Hello Howard. I haven't towed it yet just got it done this afternoon but I doubt it will make that much of a difference in braking force. If I had also replaced the 14 gage wire from the junction box all the way to the the axels with 12 gage, probably would notice an improvement.

Now I'm slow grilling T-Bones for supper.

Gotcha. I was just curious, I've heard that it makes a big difference, but have never really read of anyone that has actually done it and posted back.

We had lunch at our grandsons BBQ joint: "Wolfepack BBQ". Best ribs anywhere. But I'm always open to T-bones.

 

[traveldawg]

Well I think I found our problem. We had a nice day today and so I spent all afternoon replacing the brake wiring on our axles. The front axle had two places of frayed wire and the rear axle had one area that was bad inside the axle tube part of the way down the tube and the OEM wire is double insulated. Anyone of these bad places in the wire touching the axle tube and it would give us a short in the brake wiring and the problem we were experiencing. It was intermittent at first and progressively got worse. When we left Tucson this spring I didn't think I was going to get the error to go away and then it was ok all the way to Indiana.
Installed new 12 gage wire, sealed splices, encased in convoluted tubing and tie strapped to the back side of the axles. Yeah the rest of the brake wiring seems to be 14 gage wire. Well anyway got the bad places fixed so we should be good to go now.

Nice find. Glad you figured it out and glad you took the time to post.

 

[Redapple63]

Excellent write up! Do you think the areas that degraded were from movement and rubbing?

That’s what it looks like to me.

Bill

 

[Scott'n'Wendy]

Good find there! Thanks for posting it up.
14 ga will take care of brakes pretty well. 12ga is better but doubt you will notice any braking difference.

MMMMMMM....T-bones.....

 

[Scott'n'Wendy]

Excellent write up! Do you think the areas that degraded were from movement and rubbing?

That’s what it looks like to me.

Bill

Me too....

 

[Steven@147]

I uploaded a video to our You Tube channel on how I replaced the axle wiring, which is a not profit channel. If you can stand my dead pan demeanor, I was tired and hurting from crawling around in the gravel. https://youtu.be/iF4wVd_MCs8

Not positive what caused it, sure looks like vibration and rubbing on the axle tube because it looks like someone took find sand paper to the wires.. Could have also been skinned when they pulled the wire through the axle tube if they were not careful, then the skinned area rubbed on the tube.

I'm not sure how much difference its going to make by replacing the axle wiring. I suspect that I "may" feel a difference once I try to brake above 20 MPH. As I read on the HDRAM forum, RAM puts out diminished trailer braking voltage/amps below 20 MPH so on my usual manual brake test starting out towing I probably won't notice much. But we'll see, it's got to be better, I mean you kind of get that pucker factor coming down a hill and get a "Trailer Brakes Disconnected" warning but then it goes away.

Oh, Man,,,,, the T-bones were delicious, slow grilled for an hour 30 minutes then topped with garlic butter !!!

 

[el Rojo]

Thanks for the write up Steven.

Red

 

[dschonfeld]

Our RAM 3500 brake controller error diagnosed!

Every once in a while we get the CTBW "Check Trailer Brake Wiring" message or TBD "Trailer Brake Disconnected" warning.

When we left Tucson this spring we got the warning message on the truck after a hard stop and it took a long time for us to get it cleared. I had thought it was just the 7 way plug but now I'm not so sure. I don't want it to happen again at a bad time with no RV brakes. I've read on the forum a lot of owners have had this problem and found frayed or shorted wires inside the axle tubes or found undersized wires. I'm in the process of planning to remove and replace the RV brake wires running through the axle tubes. Some have replaced the brake wires with a larger 10 gage wire.

I found a really good conversation on a RAM HD forum explaining how the RAM Integrated Trailer Brake Control Module works, in conjunction with speed, truck brake pedal or trailer brake manual selector, something I haven't seen before. The conversation also explains how at speeds below 20 MPH, trailer braking is reduced by the Brake Controller. It's a real good write up and backed up by OBDII data placed in charts and graphs. Also explains the differences between "Light and Heavy Electrical", Light and Heavy Electrical over Hydraulic selections and what it does to the trailer brake controller output.
Read here - https://hdrams.com/forum/index.php?threads/brake-controller-troubleshooting-technical-info.6004/

For me, I believe the information is factual, I did a selected copy and paste from the RAM HD forum and printed it out and inserted it into the truck owners manual. The owners manual doesn't give you much info at all about how the truck trailer brake systems works.

Thought I would share the info I found. When I get my brake wires removed and replaced I'll tell you the results of what I found.

Great resource, thanks! We also were experiencing a very intermittent CTBW error on the dash in our 2017 RAM 3500 (pulling a 2018 Solitude 384GK). It first happened in 2021 of course in the mountains of Vermont. From then on, it would happen every 200-1000 miles of towing. We'd go days and days with no issue, and then it would happen several times in a row. At first we thought it was correlated to bumps on the road, but it also happened when towing smoothly. It usually happened after being on the road a while, but sometimes was in the first 10 minutes. We looked at the wiring, and tried everything. Contact cleaner in the 7pin, dielectric grease. Bending the blades together in the connector. A carefully designed dance and hopping on one foot.

Then we spoke to our dealer, who had a text message (they sent me the screenshot) explaining that multiple times they had found that RAMs pulling Solitudes requires an SAE certified 7pin connector on the trailer (female) side. Apparently the factory installed 7pin on our solitude was not technically SAE certified because it had the two blades in the connector that pinched the blade coming out of the truck. The SAE certified connectors, like the Hopkins one they recommended, had only a single blade that pushed against the blade from the truck side of the connector. EDIT: buried in that reference post is this set of pictures. Exactly what I'm talking about. https://hdrams.com/forum/index.php?...oubleshooting-technical-info.6004/post-102837

The brake controller would at times not have enough surface area connectivity to register that the trailer was connected. The solution: replace the 7pin connector on the trailer with a $10 new one That has a single flat surface not the two blades that squeeze together (and can bend apart).

It's an easy swap although in ours, the old 7pin was molded on (most connectors have a screw you remove to take off the connector) so the procedure was literally to saw it off (disconnect 12v battery first!) and then reconnect the new one. So I let the dealer do it. We've towed near 10K miles since the fix without a single issue.

 

[Steven@147]

snip

Then we spoke to our dealer, who had a text message (they sent me the screenshot) explaining that multiple times they had found that RAMs pulling Solitudes requires an SAE certified 7pin connector on the trailer (female) side. Apparently the factory installed 7pin on our solitude was not technically SAE certified because it had the two blades in the connector that pinched the blade coming out of the truck. The SAE certified connectors, like the Hopkins one they recommended, had only a single blade that pushed against the blade from the truck side of the connector. EDIT: buried in that reference post is this set of pictures. Exactly what I'm talking about. https://hdrams.com/forum/index.php?...oubleshooting-technical-info.6004/post-102837

The brake controller would at times not have enough surface area connectivity to register that the trailer was connected. The solution: replace the 7pin connector on the trailer with a $10 new one That has a single flat surface not the two blades that squeeze together (and can bend apart).

It's an easy swap although in ours, the old 7pin was molded on (most connectors have a screw you remove to take off the connector) so the procedure was literally to saw it off (disconnect 12v battery first!) and then reconnect the new one. So I let the dealer do it. We've towed near 10K miles since the fix without a single issue.

This is what a lot of owners refer to as the old style and new style 7 pin connector. We have the old style (double blade pinch style?) and I haven't changed it yet to the single blade new style. I'll get to it sooner or later.

Yeah such a pain to chop off the old connector and install the new. Absolutely disconnect the RV battery when changing the 7 pin connector, because pin 4 is going to be energized 12VDC all the time from the RV battery unless the battery is disconnected.

I read where some people were referring to the CTBW message (check trailer brake wiring) as an open brake circuit indication and the TBD message (trailer brakes disconnected) as a shorted brake circuit but I'm not sure about that.

No matter what kind of error a person is getting from their tow vehicle, you got to start trouble shooting like from the 7 pin trailer connector through the cord and into the junction box and keep testing all the way to the wheel brake magnets until you find the cause. Some owners have found their particular problem was the wires on the brake magnets came loose inside the wheel and shorted against the brake assembly. You got to take the wheel brake drum off to check that.

Once I got our axle rewiring done I hooked up our truck and tested each wheel, they all are working fine. I could even hear the "ticking" sound at each RV wheel that they talk about in the HD RAM forum brake operation, its the RAM trailer brake controller pulsing the brake circuit to make sure its still connected. Funny I had never paid attention and heard it before, but its there.

Hope anyone having brake problems can use this thread to find their brake problem. An intermittent brake problem is the hardest to find because its not a hard and constant fault.

 

[tubastew]

I too am a victim of CTBW followed by TBD messages. I had pretty much proven to myself there was nothing wrong with the RAM brake controller on my 2020 Ram 3500, as I was an RV transporter for awhile and never got the messages while pulling the 18 new trailers cross country.

I read messages, looked at YouTube videos, and did my own diagnostics. I changed the 7 way plug (not the problem); I changed the magnets and drums (again not the problem, but after 50k miles was showing a good amount of wear); I spoke with a local trailer fabricator who said the factory controllers are so sensitive the delay in longer trailers could cause error messages to display and their solution was to install a wheel magnet closer to controller, i.e. in the tongue of the trailer (once again, not the problem).

The only thing left was the wiring. A visual inspection did not find any faults. I could not recreate the problem while wiggling wires while my wife pressed the brakes. I dreaded having to run the wire from the kingpin back to the axle. I decided to replace the wires that run through the axle first. My plan was to install new grommets in the holes and run new wires through the axle. I cut the wires from the brakes and tied new wire, and then black tape around the splice. As luck would have it, when I pulled them through the axle, they got stuck coming out of the hole and I broke the splice.

At any rate I found this blog and discovered my problem was a common occurrence and the solution was to use wire ties to secure the wires to the back of the axle. Fortunately for me, Harbor Freight is right up the road. Wire ties, heat shrink butt connectors, and heat shrink tape were all available.

Upon inspection, each axle wire had bare metal exposed. The worst spot was somewhere in the middle of the rear axle.

I’ve included pics of the frayed wire and the new installation. Thanks to all the contributors on this topic. BTW, I disconnected the magnets in the kingpin, it was an amperage parasite.

 

[ajg617]

Interesting. I got my first trailer disconnect message (twice) pulling the RV up to the repair shop last month while on the highway with my 2020 Ram. Have never seen that before.

 

[Steven@147]

REplacing the brake wires in the RV axle tubes totally eliminated our problem. Wont cure everyone's problems but it fixed ours.

 

[Wileykid]

I had problems on my last trailer of the dreaded "service trailer brake" warning. I finally found a pinched wire where it crossed the frame near the brake backing plate. Wiggle it all you want, no problems, go over a good bump, wire would pinch in the frame, and get the warning. Replaced all the wires in that area along with proper way to run them around the frame, no problems after that.