Trailer Brake Lockup While Driving 55 MPH

[ino1thing]

2018 GD 310GK (Solitude). 2020 Chevy Silverado 3500. Using OEM brake controller. While driving approx. 55 mph and without touching brake pedal the trailer brakes locked up briefly (1 second or less). Caused a skid of 8 feet and threw a bunch of smoke. When we pulled over to investigate, the trailer brakes did not work.

Turned off truck, pulled and reinstalled 7-pin umbilical. Wiggled it around a bit. Started truck and noticed a diagnostic message saying traile brake connection was inoperative. Turned off truck, pulled and reinstalled umbilical and now truck diagnostic status reports brake connection is good.

Drove slowly to camp site, brakes working fine. Tried to measure voltages while pressing brake pedal and/or brake controller without much success, as discussed in other posts (due to complexities of ABS and whatnot). Will try again with trailer plugged in if I have a second 7-pin connector on bumper.

Inspected wires at each brake but did not observe any issues. When brake is applied I can hear buzzing from brakes. Inspected back side of truck bed 7-pin connector and it appears ok.

Inspected connections where trailer umbilical connects to trailer in junction box. All looks good.

The behavior of the lockup is similar to what would happen if the breakaway switch had activated. Inspection of these connections looks good and the plunger is intact. I've never tested this circuit as recommended elsewhere in these forums.

Wondering if this is the most likely culprit. Should I replace it? Have to drive home in a couple days (200 miles) so looking for quick responses.

Thanks.

 

[Soundsailor]

2018 GD 310GK (Solitude). 2020 Chevy Silverado 3500. Using OEM brake controller. While driving approx. 55 mph and without touching brake pedal the trailer brakes locked up briefly (1 second or less). Caused a skid of 8 feet and threw a bunch of smoke. When we pulled over to investigate, the trailer brakes did not work.

Turned off truck, pulled and reinstalled 7-pin umbilical. Wiggled it around a bit. Started truck and noticed a diagnostic message saying traile brake connection was inoperative. Turned off truck, pulled and reinstalled umbilical and now truck diagnostic status reports brake connection is good.

Drove slowly to camp site, brakes working fine. Tried to measure voltages while pressing brake pedal and/or brake controller without much success, as discussed in other posts (due to complexities of ABS and whatnot). Will try again with trailer plugged in if I have a second 7-pin connector on bumper.

Inspected wires at each brake but did not observe any issues. When brake is applied I can hear buzzing from brakes. Inspected back side of truck bed 7-pin connector and it appears ok.

Inspected connections where trailer umbilical connects to trailer in junction box. All looks good.

The behavior of the lockup is similar to what would happen if the breakaway switch had activated. Inspection of these connections looks good and the plunger is intact. I've never tested this circuit as recommended elsewhere in these forums.

Wondering if this is the most likely culprit. Should I replace it? Have to drive home in a couple days (200 miles) so looking for quick responses.

Thanks.

My initial thought after reading your title was the controller. After reading the whole post it also seems reasonable that you have a partially stripped wire causing the brake lock up. A few folks on the forum have found worn wires, could that be your culprit?

 

[ino1thing]

Thanks for the quick response Soundsailor! If there are any stripped or exposed wires, they are not visible in the areas I've inspected. Perhaps inside drum somewhere. Might explain intermittent nature of the truck's diagnostics.

Hope it's not the OEM controller.

So, if a stripped wire in that circuit goes to ground, will that activate all 4 brakes?

 

[finz04]

Check your emergency breakaway switch as well. Perhaps there is an intermitent short. That would lock up the brakes.

 

[Wileykid]

Pull the pin on the emergency switch, check that it works, and look inside it. On my last trailer, on one of my does it work, it did not. I inspected it and found it to be fried internally. Not sure how that happened, but was simple to replace the switch.

I am not sure how, but maybe the contacts or wires could have momentarily shorted?

 

[Riverbug]

If it isn't something do to with the emergency switch, then you might pull the tires and hubs. I had random troubles (not exactly like your situation) but did not find the issue until I did hub maintenance. Once I had eyes on the brake assemblies I found a wire had pinched, worn the insulation off, and was shorting against a spindle. If you have exhausted all other potential problems, might be a place to check. Otherwise, you may need to follow the wires and check for shorts.

 

[ino1thing]

We do not have cell service at camp site, so my responses will be sporadic at best. Really appreciate all the assistance.

I replaced the breakaway switch and busted the old one open to inspect. It looks fine. Very simple operation. Not much to go wrong inside.

Guess I'll have to try some of the other ideas when I get home.

 

[wannabervin]

Thanks for the quick response Soundsailor! If there are any stripped or exposed wires, they are not visible in the areas I've inspected. Perhaps inside drum somewhere. Might explain intermittent nature of the truck's diagnostics.

Hope it's not the OEM controller.

So, if a stripped wire in that circuit goes to ground, will that activate all 4 brakes?

The brake wires run through the axles. We had an issue with the brakes disconnecting and reconnecting while driving. (But not locking up). Dealership replaced the wiring, this time zip tied to the outside of the axles. Service manager showed me the old wires. Very brittle and frayed. No issues since.

 

[ino1thing]

The brake wires run through the axles. We had an issue with the brakes disconnecting and reconnecting while driving. (But not locking up). Dealership replaced the wiring, this time zip tied to the outside of the axles. Service manager showed me the old wires. Very brittle and frayed. No issues since.

Thanks for the feedback wannabervin. I've read similar stories elsewhere. We had another occurrence of lockup on the way home AFTER I disconnected the OEM brake controller by cutting the brake wire in the 7-pin pig tail at the trailer junction box and verifying with multimeter that there was no voltage going to trailer brake wire when brakes applied in truck. I had to pull over and after much consideration, I cut the brake wires at the driver's side hubs (since we had already decided to drive home without trailer brakes and simply relying upon engine brake, exhaust brake and truck foot brake.

After getting home safely, I disassembled a couple hubs to inspect for wiring damage and found none. I cannot figure out where the voltage to activate the brakes is coming from, so I ended up taking it into a service shop. After describing the whole story to their head mechanic, he could not come up with anything either, but he agreed to keep the trailer and troubleshoot further using his own truck. His first thought was the OEM brake controller went rogue, but then he verified I cut the correct wire so now he needs to think a bit harder.

 

[Steven@147]

Thanks for the feedback wannabervin. I've read similar stories elsewhere. We had another occurrence of lockup on the way home AFTER I disconnected the OEM brake controller by cutting the brake wire in the 7-pin pig tail at the trailer junction box and verifying with multimeter that there was no voltage going to trailer brake wire when brakes applied in truck. I had to pull over and after much consideration, I cut the brake wires at the driver's side hubs (since we had already decided to drive home without trailer brakes and simply relying upon engine brake, exhaust brake and truck foot brake.

After getting home safely, I disassembled a couple hubs to inspect for wiring damage and found none. I cannot figure out where the voltage to activate the brakes is coming from, so I ended up taking it into a service shop. After describing the whole story to their head mechanic, he could not come up with anything either, but he agreed to keep the trailer and troubleshoot further using his own truck. His first thought was the OEM brake controller went rogue, but then he verified I cut the correct wire so now he needs to think a bit harder.

My thoughts, normally power to actuate the RV brakes only comes from two independent sources. Pin 2 of the 7 way being fed from your trucks brake controller. Or RV battery power direct to the RV brakes through the brake away switch.

If you have a brake wire in the RV hard shorted to ground your truck should sense this and disconnect further braking action. In this case you should get a "Trailer Brake Disconnect" message from your truck. In the case of an intermittent brake wire short to ground you may get a "Check Trailer Brake Wiring" message from your truck. I think GM, Ford and Ram all send a short brake pulse through pin 2 of the 7 way connector to the RV to make sure the brakes are still connected.

Now if you cut the pin 2 wire of the 7 way, that should kill that brake power source. And if you replaced the brake away switch that should eliminate that possibility. Now this is an RV Without ABS.

From what I hear all new drum brake RVs coming from GD all have ABS. This puts a whole new wrinkle in RV braking action. I do not know for sure how the manufacturer installs the RV ABS system or how its powered. But I would check out the RV ABS controller to make sure it is not randomly sending out power to the RV brakes. If you can find the ABS controller, disconnect the power feed into it, should be just a plug and see if your problem goes away, Admittingly if you disconnect the ABS controller there probably will not be any brakes on the RV but I don't know exactly how these RV ABS systems work.

Here's a diagram I found of Lipperts RV ABS system, yours should be similar. I would suspect the RVs ABS controller,

 

[Chaps2018]

I recognize this discussion is focused on wiring/controllers.

Just wanted to add my recent experience where a wheel locked up at speed and resulted in a flat spot/blowout.

In changing the wheel I noticed the hub would not rotate forward—only backwards.

I removed the hub to find the adjustment star screw/barrel assembly had fallen out of the Dexter Never-Adjust brake plate. After the star adjuster screw wore down enough it wedged in between the pad and drum effectively locking up the
Hub.

I had just installed a new brake plate 2k miles ago.

Upon inspection of the failed brake plate assembly, I could not find any defects that would have caused the adjuster screw to fall out.

 

[ino1thing]

My thoughts, normally power to actuate the RV brakes only comes from two independent sources. Pin 2 of the 7 way being fed from your trucks brake controller. Or RV battery power direct to the RV brakes through the brake away switch.

If you have a brake wire in the RV hard shorted to ground your truck should sense this and disconnect further braking action. In this case you should get a "Trailer Brake Disconnect" message from your truck. In the case of an intermittent brake wire short to ground you may get a "Check Trailer Brake Wiring" message from your truck. I think GM, Ford and Ram all send a short brake pulse through pin 2 of the 7 way connector to the RV to make sure the brakes are still connected.

Now if you cut the pin 2 wire of the 7 way, that should kill that brake power source. And if you replaced the brake away switch that should eliminate that possibility. Now this is an RV Without ABS.

From what I hear all new drum brake RVs coming from GD all have ABS. This puts a whole new wrinkle in RV braking action. I do not know for sure how the manufacturer installs the RV ABS system or how its powered. But I would check out the RV ABS controller to make sure it is not randomly sending out power to the RV brakes. If you can find the ABS controller, disconnect the power feed into it, should be just a plug and see if your problem goes away, Admittingly if you disconnect the ABS controller there probably will not be any brakes on the RV but I don't know exactly how these RV ABS systems work.

Here's a diagram I found of Lipperts RV ABS system, yours should be similar. I would suspect the RVs ABS controller,

Thank you Steven@147!

I contacted GD and confirmed that my trailer does NOT have ABS system. They just began installing this system last year, while mine is from 2018. So, we're still looking for the 12V source. Stay tuned!

 

[ino1thing]

I recognize this discussion is focused on wiring/controllers.

Just wanted to add my recent experience where a wheel locked up at speed and resulted in a flat spot/blowout.

In changing the wheel I noticed the hub would not rotate forward—only backwards.

I removed the hub to find the adjustment star screw/barrel assembly had fallen out of the Dexter Never-Adjust brake plate. After the star adjuster screw wore down enough it wedged in between the pad and drum effectively locking up the
Hub.

I had just installed a new brake plate 2k miles ago.

Upon inspection of the failed brake plate assembly, I could not find any defects that would have caused the adjuster screw to fall out.

Thanks for the feedback bjlakatos. We will keep an eye out for similar mechanical failure mechanism.

 

[ino1thing]

We took the trailer to an RV mechanic who performed a fairly thorough checkout, including impedance testing of all wires in braking circuit. No shorts were found. The mechanic towed the trailer before reconnecting any of the wires that I cut, using his own truck, and verified there were no trailer brakes and he experienced no brake lockups during a 30 mile road trip. He then repaired all the cut wires, performed the impedance tests and towed it for another 30 miles with no brake lockups. He released the trailer to me since he could not duplicate the problem.

I took the truck to a Chevy dealer and requested diagnostics on the trailer braking systems. They found a C1114 code had been thrown. Further analysis led them to conclude that the Integrated Brake Controller Power Control Module was faulty so I had them replace it. This is one of three or four modules mounted under the truck bed above the spare tire.

Hopefully, this proves to be the fix. We'll find out during our next trip in a couple weeks.

Thanks to everyone for the thoughtful feedback.

 

[Scott'n'Wendy]

Thanks for posting up your results.
Knowing if the Chevy trailer controller faults it could lock up the trailer wheels would have me a bit nervous. Maybe they can all do it but I hadn't heard of it before.

 

[huntindog]

2018 GD 310GK (Solitude). 2020 Chevy Silverado 3500. Using OEM brake controller. While driving approx. 55 mph and without touching brake pedal the trailer brakes locked up briefly (1 second or less). Caused a skid of 8 feet and threw a bunch of smoke. When we pulled over to investigate, the trailer brakes did not work.

Turned off truck, pulled and reinstalled 7-pin umbilical. Wiggled it around a bit. Started truck and noticed a diagnostic message saying traile brake connection was inoperative. Turned off truck, pulled and reinstalled umbilical and now truck diagnostic status reports brake connection is good.

Drove slowly to camp site, brakes working fine. Tried to measure voltages while pressing brake pedal and/or brake controller without much success, as discussed in other posts (due to complexities of ABS and whatnot). Will try again with trailer plugged in if I have a second 7-pin connector on bumper.

Inspected wires at each brake but did not observe any issues. When brake is applied I can hear buzzing from brakes. Inspected back side of truck bed 7-pin connector and it appears ok.

Inspected connections where trailer umbilical connects to trailer in junction box. All looks good.

The behavior of the lockup is similar to what would happen if the breakaway switch had activated. Inspection of these connections looks good and the plunger is intact. I've never tested this circuit as recommended elsewhere in these forums.

Wondering if this is the most likely culprit. Should I replace it? Have to drive home in a couple days (200 miles) so looking for quick responses.

Thanks.

The breakaway switch is a prime suspect. I have had a faulty on on a new trailer. I have replaced quite a few over the years
They are cheap enough to make it the first thing to try

 

[ino1thing]

Thanks for posting up your results.
Knowing if the Chevy trailer controller faults it could lock up the trailer wheels would have me a bit nervous. Maybe they can all do it but I hadn't heard of it before.

I read somewhere that these integrated brake controllers periodically pulse the trailer brake circuit to verify whether a trailer is connected and to determine what kind of brake circuit is connected. I took this to mean that a voltage is applied. It is not a stretch to me to imagine that if the power control module is failing or faulty that this voltage pulse could be large at times and thus cause a brief brake lockup.

 

[ino1thing]

The breakaway switch is a prime suspect. I have had a faulty on on a new trailer. I have replaced quite a few over the years
They are cheap enough to make it the first thing to try

This is the first thing we tried. The only breakaway switch I could find while at the campsite was a 3-wire version at a NAPA store, so I put that one on. I believe the third wire supported the built-in test function. It had a button to press and an LED light would turn on if the test was successful. I did not like this added complexity, so I had the RV technician replace this with a standard 2-wire version.

 

[Riverbug]

We took the trailer to an RV mechanic who performed a fairly thorough checkout, including impedance testing of all wires in braking circuit. No shorts were found. The mechanic towed the trailer before reconnecting any of the wires that I cut, using his own truck, and verified there were no trailer brakes and he experienced no brake lockups during a 30 mile road trip. He then repaired all the cut wires, performed the impedance tests and towed it for another 30 miles with no brake lockups. He released the trailer to me since he could not duplicate the problem.

I took the truck to a Chevy dealer and requested diagnostics on the trailer braking systems. They found a C1114 code had been thrown. Further analysis led them to conclude that the Integrated Brake Controller Power Control Module was faulty so I had them replace it. This is one of three or four modules mounted under the truck bed above the spare tire.

Hopefully, this proves to be the fix. We'll find out during our next trip in a couple weeks.

Thanks to everyone for the thoughtful feedback.

Really good to know, wouldn't have thought to check for a thrown code on the truck. Hope that turns out to be your solution.