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Some owners equip their Toyota with an aftermarket brake controller, which is used to activate the brakes on the trailer. As it taps into the vehicle's electrical wiring, this electronic device may interfere with the operation of the Pre-collision system. The solution to the problem is the addition of an extra relay, which triggers the controller only when braking.
I don't have a wired brake controller, it is an Echo Wireless Bluetooth controller which plugs right into the receiver on the car and then my 7-pin plugs into that. I have ordered a new brake controller (because they insist that's the problem, too) but it hasn't come in yet.
With the failure happening with just the trailer plugged in without the wireless controller I would be checking to make sure the ground circuit on your trailer is good. Looking at the Airstream Bambi wiring diagram the trailer brakes and lights connect through a grounding bus bar, if the chassis ground to the bus is poor the lights could be feeding back through the brake circuit (or visa versa). Just trying to help diagnose remotely
With the failure happening with just the trailer plugged in without the wireless controller I would be checking to make sure the ground circuit on your trailer is good. Looking at the Airstream Bambi wiring diagram the trailer brakes and lights connect through a grounding bus bar, if the chassis ground to the bus is poor the lights could be feeding back through the brake circuit (or visa versa). Just trying to help diagnose remotely
thank you for this suggestion. I will check it now!
There is a mentioned in owners manual that you may need to disable PCS while towing another vehicle. Is this vehicle reference in owner's manual a trailer? I can't say for sure
Hi! I recently purchased a 2020 GX specifically for towing. I picked my camper up for the first time Wednesday (16ft Airstream, dry weight 3,000lbs) and within 2-3 miles I got a PSC Malfunction notice. I took it to the dealer the next day and they couldn't see anything wrong so they cleared the codes. Saturday, I went to move the camper again, and within 2-3 miles again, I got the warning. I went to the dealership with the camper and again they found nothing, aaa technician rode with me for about 5 miles and the warning didn't return, so we hoped it was solved. Nope. About 28 miles on the interstate with no issues, got off the highway and I got the warning again. I am a super frustrated to say the least. Has anyone experienced this? Any ideas where to start? I have an appointment at an RV shop Thursday to make sure I adjusted the hitch setup correctly.
Hi missdovi! I have the same year GX like yours (premium) and had the same problem yesterday. I was towing a 19cb Airstream (slightly bigger than yours) with a new WDH and within 2 miles on road, I got the pre-collision system malfunction warning. I continued driving 30 miles home though and didn't feel anything different in driving besides the annoying warning message. I used the same echo wireless brake controller like yours.
Before this trip, I had towed it several times for a total of 500 miles with my old WDH, and I have never seen this problem. The only different factor is my new WDH, but I had it professional installed at a RV dealer, and there was no visual sagging or anything when I looked at it.
I haven't taken my GX to the dealer yet and came across your post here. Did you find out the cause? Appreciate you sharing what you find.
