Trailering Dilemma - Help!!!

[Brent Wall]

I am greatly disturbed because I have a new VLX setting in my driveway that I cannot use. Let me explain.

Twice in the past two weeks when the boat trailer was attached to our tow vehicle, we lost electrical power to a variety of functions including all the towing connections. Of course, this makes it impossible to back the trailer without a mechanical lockout. Fortunately, in the first instance, we were at home so a mechanical lockout was readily available. More importantly, Lexus covered the $1500 repair to the vehicle electrical system under warranty.

On Monday, the same thing happened again. However, this time it occurred at the top of the boat ramp and we were stuck there until my wife could drive home, retrieve the mechanical lockout and return to the lake with it. (It’s a good thing the ramps were not busy). Lexus again repaired the vehicle under warranty; this time by replacing several fuses.

Now the major dilemma. The Lexus folks are saying the problem must be the trailer wiring but my Malibu dealer says that the trailer checked out OK before delivery (3 months ago). This scenario ultimately means I’m stuck in the middle with a boat I can’t get to the lake without serious financial risk. Although Lexus has resolved the problem under warranty twice, they may not cover it again since they believe the problem is the trailer wiring. (Recall that the bill for the first instance was $1500).

I could really use your advise in getting this issue resolved. What are your thoughts on the cause of this issue and how to get it resolved?

[Bill_AirJunky]

So are you using any adapters of any kind? ie; 5 flat - 7 round? If so, get new ones for testing.

Easiest way I can think of diagnosing the problem is to hook the trailer to another truck.

Or hook the truck to another trailer?

[Brent Wall]

So are you using any adapters of any kind? ie; 5 flat - 7 round? If so, get new ones for testing.

Easiest way I can think of diagnosing the problem is to hook the trailer to another truck.

Or hook the truck to another trailer?

Yes, I am using a 5 flat to 7 round adapter. Also new.

Keep in mind, I have towed the new boat without incident on a dozen other occassions.

[RTS]

Do you have an invoice showing what Lexus repaired? That may help with the diagnosis. What electrical components are going bad when the trialer is hooked up? Certainly not just a fuse, right?

First thing I would do is run to the store and get another adapter and see if that fixes things.

Edited June 17, 2009 by rts

[UberXY]

Somewhere, you have a hot wire that is going to ground.

Think back: did the problem happen when:

1. you used a turn signal?

2. you hit the brakes?

3. you put the car in reverse?

4. you turned on the parking lights or headlights on the Lexus?

If you can positively answer yes to any of these questions, it's gonna be easy to track down. If all are no, and it just happens, that's gonna be tough.

It's a good idea to carry a spare lockout in the car, but I bet you have that figured out now. I used to keep one on the boat keychain.

Ub

Edited June 17, 2009 by UberXY

[Brent Wall]

Somewhere, you have a hot wire that is going to ground.

Think back: did the problem happen when:

1. you used a turn signal?

2. you hit the brakes?

3. you put the car in reverse?

4. you turned on the parking lights or headlights on the Lexus?

If you can positively answer yes to any of these questions, it's gonna be easy to track down. If all are no, and it just happens, that's gonna be tough.

It's a good idea to carry a spare lockout in the car, but I bet you have that figured out now. I used to keep one on the boat keychain.

Ub

In both cases we were either backing up or getting ready to back up. In the first instance I can't say for sure whether the issue occurred before or after we put the vehicle in reverse. In the second case, I know that we had not put it in reverse, just stopped at the top of the ramp. Of course, this implies that we hit the brakes. However, we hit the brakes lots of times on the way to the lake without incident. Seems to be very intermittent.

[skyskier]

Since it only happens when the trailer is hooked up, logic says it must be a problem with the trailer wiring. I would ask your Bu dealer to go over the trailer wiring inch by inch. Documentation and certification from your Bu dealer may help you with the Lexus dealer if it happens again. Hopefully your Bu dealer will find the problem. Best of luck!

[UberXY]

In both cases we were either backing up or getting ready to back up. In the first instance I can't say for sure whether the issue occurred before or after we put the vehicle in reverse. In the second case, I know that we had not put it in reverse, just stopped at the top of the ramp. Of course, this implies that we hit the brakes. However, we hit the brakes lots of times on the way to the lake without incident. Seems to be very intermittent.

It's gonna be tough to track down with a voltmeter. I guess the best thing you can do is crawl under the trailer and look for a place where the wiring harness could be chafing against the trailer frame.

Best of luck. I have six trailers and it seems like something electrical is always wrong with one of them.

Ub

[H2Idah0]

If you have a swivel tongue on your trailer AND you swivel it when you park your trailer, start there.

[jayjoans]

+1

I'd start at the swivel tongue if you have one. I had some trailer electrical issues too and it traced back to wires that had been pinched in the swivel and compromised. They were difficult to see just by glancing, but closer inspection found them in bad shape.

[Faceplant409]

I'll third the swivel tongue inspection. I've had it happen once, JUST once.

Good luck!

Patrick

[JeffS]

There are trailer wiring adapters that isolate the truck from the trailer wiring.

These have their own 12V lead, with a fuse, so you are not using power from the car's internal electrical systems, just a direct connection to the battery.

Hoppy is the most common maker of these that I know of.

The way it gets wired - the wiring senses that a bulb has power to it, uses it's own relays to light the trailer lights.

And uses the 12V from the battery to power it.

Takes the truck out of the equation. And if you have a short that does not get caught by the fuse - the worst that can happen is you blow a $75 wiring control module.

-Jeff

[SmoothWaterMan]

I'd go back to the repair bill on the Lexus first, as someone mentioned. See just what it was that needed to be replaced, and see where that is in the electrical path. 99 out of 100 times an electrical problem on a trailer involves or is a bad ground. (Typically between trailer and tow vehicle)

Something to consider is to make sure the Lexus subscribes to the standard electrical pattern on their plug. Can't see why they wouldn't, but I've had some friends with Toyota's that needed additional accessories on the truck side to make it work.

Peter

[NvBoarder]

It sounds like it is a problem when you are backing the trailer. Don't know what kind of trailer it is but on the extreme trailer their is a relay attached to the master cyclinder of the trailer. When you put the veichle in reverse and the back up lights kicks on, that sends a signal to the relay that goes into bypass mode so the trailer doesn't lock up on you. This might be the bad wire or something along the lines of that. This is what I would do. Get a lead tester, fairly cheap looks like a screwdriver with a light inside and a wire with a clip to ground it and check each prong on the veichle and make sure that you know what prong does what, Brake, turn signal, reverse light. Then varify that the trailer wiring is set up the same way. If all of that is good then find the wire that goes to the relay and check to make sure it is good all the way back to the relay. Chances are good that when you put the truck into reverse it is crossing with another signal and shorting out. Could be as simple as a bad adapter plug but at least then you will know that everything lines up properly. My truck has a fuse designated to the reverse lights so if their is a short it pops and doesn't blow up the entire electrical system in the veichle which sounds like what is going on with you. Might not hurt to put a inline fuse between your backup lights and the rest of the system. Maybe your veichle has one but I thought it couldn't hurt to bring up. Good luck hope this helps

[MalibuTime]

If you have a swivel tongue on your trailer AND you swivel it when you park your trailer, start there.

One of the first things I did to my trailer was wrap all of those wires into a corrugated plastic wire loom. Same with the tower. Packages of that stuff are only like $2 at Frys.

[Killer]

I will all but gaurantee that its the yota, not the trailer.... BAD GROUND or wires are crossed in the harness

my family had a Rav4 that would blow fuses everytime you hooked up the flat 4, the hitch was an aftermarket one, but it never had a good ground, so we found our own way up by the tail light and hooked it up that way, bypassing the ground wire in the harness.

also had a subaru outback that did the same thing... my only explaination is they don't tow in Japan...

[Bake's Marine]

Any luck?

My guess is that you have a short in the trailer and the vehicle is not protected properly. With a multimeter you could tell if you have a problem with your trailer in about 30 seconds. Too bad your not close to Bake's i would gladly offer a hand to help diagnose the issue.

Best of Luck!

-Paul

[the_dude]

First,

Unless Lexus totally botched the design you should blow a fuse before damaging the vehicles electrical if the trailer wiring is shorting to ground.

Second you can see if there is a current short to ground on the trailer with a multimeter using the ohm meter function. Just press it against a good ground spot on the trailer and each circuit on your 5 prong plug (obvioulsy ground should give a nice reading).

I actually have a short to ground that has developed on my trailer recently and it would just blow a fuse in the truck until I fixed the problem.

[electricjohn]

On my Nissan pick up truck, fuse protection was overlooked on the trailering circuits by the designers. They had to recall my truck to add a harness extention with the fuses for those circuits. Short circuits on trailers were cooking the Body Control Module (BCM) which is a computer processor that controls everything in the vehicle except the drivetrain. This just goes to show engineers can put a faulty tow vehicle out on the market.

[68Slalom]

I agree with NVBoarder, you need to trace all the outlets on the connector from the truck. Using the test light you will know which stem controls what and there may be one hooked up in the truck that is not needed for your trailer. Once you map out which ones you need on the truck do a one by one test on the trailer, this really should be something your dealer can help you with even if it's a small fee of the technicians time I would lean towards trying to get some help from people that do it all the time. If it is something the dealer did wrong/right under warranty it may not be matching up with the trailer now.