Trailer Brake Error & Pre-Collision System Malfunction warnings

Last month while towing my horse trailer I got these two warnings flashing on my dash. I had hauled to an event in the morning with no problems but when I got in vehicle to go home, these warnings were there. Have not noticed any issues with the feel of braking. And I have lights and signals working throughout.
I hitched to our flatbed trailer to determine if it was related only to the horse trailer. Nope. I get the warnings with either one.
HISTORY: I’ve had this truck for 3 yrs and from the beginning I’ve had an intermittent message with the IBC telling me the trailer was disconnected. Also have had the collision warning go off at seriously weird times but intermittently as well. Weird meaning an oncoming car in the opposite lane (not drifting over) and the blaring sound going off. Hate that. Most recently it went off on the interstate. I was in left lane next to the divider pylons for the toll lanes. Someone in the toll lanes passed me on the left (they get to go fast because they pay $$) and that bloody alarm went off. Scared the out of me! But intermittent meaning pretty rare that either problem has happened.
Husband just took the truck to dealer (like it says in both warnings) and they had no idea and sent him on his way, so no help there.
Has anyone experienced this or have any thoughts?





UPDATE: After going back to Toyota, this time with a trailer in tow and having hooked to 3 different trailers but getting the same warnings, I stood my ground and told the tech, service writer, and another guy standing there that they needed to quit blaming the trailer and start looking at the “brain” of the truck to figure out the problem. Told them I wanted them to contact Toyota corporate to figure this out.
Well, shazam! They called a short time later and learned they had a device they could plug into the 7-pin at the back that replicated a trailer and figured out the “brain” needed a new relay. Ordered a new relay. It came in the next week. All was well and I was able to haul my horse to NC with one hiccup.
After taking a rest stop, when I restarted truck I got a different pair of warnings: “Pre-Collision System Unavailable” and “Trailer Wiring, Type, or Connection Fault”. Grrr! Still needed to get gas so went to get gas, shut it down, restarted after and haven’t seen any more warnings. Lights and brakes are working. The only change I made was to use a Velcro strap around the the trailer plug and hinged cover on the 7-pin receptacle. No issues since.
I wasn’t thrilled at having an integrated brake controller but bought the truck during COVID when it was hard to get anything. Thought “What happens when the integrated brake controller has issues?” Prefer an aftermarket which can be switched out in a jiffy for a couple hundred bucks. Integrated going bad means you have to motivate techs to go beyond their usual scope, wait for parts to come in, and return to have installed.
Never mind that on one return to Toyota my husband and I were walking in to the service lanes inside the building at closing time and somebody pushed a button for the glass roll-down door to close without checking if door was clear of any traffic, including pedestrian. The door came down directly on husband’s head, causing a nasty concussion. Still dealing with that.

 

Never had an issue towning, but my pre-collision alarm has gone off on me on the highway at odd times as well. Following.

 

I’m currently dealing with a similar issue. Turns out there is a technical service bulletin to update the software on the trailer brake controller. Toyota did this for me 3 weeks ago. I took the truck camping and it happened again. Went right back to Toyota who said the original tech forgot to clear all the old codes but that it was done and the problem should be fixed. However, the intermittent error continues.

 

I had trailer brake controller errors and intermittency that was caused by a little corrosion in the trailer 7-pin connector. Dielectric grease and working it back and forth onto the truck connector a few (10-20) times and the errors went away.

 

Driving home from work yesterday I stopped at a stoplight and my fuel gauge instantly dropped to 0 with a warning indicator. Got home, checked fuses, top of tank for bad wiring, nothing.. Started it up this morning, still reading no fuel (I had just filled it up) , started driving to work and boom, trailer brake / pre collision warning popped up. Unplugged the battery which seemed to fix the TB/ PC but still reads no fuel. Just left a troublesome F150 for the Tunda. poop..

 

Lopo, Tundra dashboards light up like a Christmas tree anytime there’s an error in the computer. The common displays reflect trailer brake and pre-collision system errors. However, this doesn’t mean the error is necessarily with either of these systems. Frustrating, I know. However, there is a known issue for trucks with an integrated trailer brake system. Therefore, your first step should be to have Toyota flash your brake controller computer then see if the problem comes back.

 

Turns out a mouse chewed on wiring in two spots above the gas tank. Little bastards…So frustrating ….
Hoping that strategic peppermint oil spray, bounce dryer sheets and traps prevent that from happening again. Grrrrrrr

 

I’ve had Pre-Collision warnings and false warnings from that alarm. If your truck is lifted, then it’s possibly the angle. When you were towing, did you ever feel light steering at any given time?

 

Honda sells an anti rodent wrap for the wiring. Apparently soy based plastics taste good to rodents.

 

Truck has the TRD Pro Fox suspension (2” in front & 1.5 in rear). I used the TRD speed sensor relocate kit and made sure all the abs/speed sensors have slack. Steering felt normal while towing and regular driving and the issue started. I’m beginning to think it’s a wiring issue. Thanks Topo for sharing your findings. I’ll take a look.

 

this happened to me and I don’t know what to do…I don’t tow anything lol.

 

Hey Cam, sometimes my check engine light is on and sometimes it’s not. The code was suggesting an issue with tranny solenoid 4. Dealership replaced it last week. So far, 200 miles without issue.