Trailer Break Override triggers ABS and VSC dash light

[gm350reratliff]

Well crap. Seems the installation process caused a fried yaw sensor. This was either caused by a faulty controller or a test probe that applied voltage to a zero voltage line. Part ordered and I had to get the trailer place to cough up a new controller and over $1600 for part and labor. Thankfully they agreed to do so.

A simple plug-and-play has turned in to a multi-week ordeal. Heads-up to *make sure* whomever is installing your controller knows what they are doing. I'm taking the replacement controller to the dealer and have them install it.

It absolutely requires a relay or diode to prevent the back feed.

If the trailer place used the factory pigtail, there shouldn't be any need to test the wires with a probe. Even if said test probe was used (if testing the factory electric brake controller pigtail) I doubt it could cause a failure like that. I'll have to go and check my 2014 but I don't recall it saying anything about the need to add a relay or diode. I still think there something screwy with Toyota's wiring.

Holy smokes. What the heck is going on here? Would a dealer normally know to add a relay/diode if they were to install the controller? I feel like this is something Toyota needs to address. This shouldn't be so complicated.

Sorry to hear about your troubles.

From 1999 to 2010 I worked at a truck accessory shop that was also next door to a RV dealer. I've installed hundreds of brake controllers over that time period on a wide array of vehicles and never remember having to add a relay or diode. Giving the issues now, that may be what is needed though. I Still feel Toyota should've provided a notice to the customer about this.

I need to figure out where to put the relay or diode.

Should be easy. Just get a SPDT (single pole double throw) relay. You want to interrupt the brake switch signal wire (commonly red on most brake controllers). With the brake signal wire cut, attach the wire coming from the vehicle to the 86 pin on the relay. The cut wire coming from the brake controller will go to the 87 pin on the relay. Now, connect a jumper wire from the ground wire (commonly white on most brake controllers) to the 85 pin. Next connect a jumper wire from the 12v supply wire ( commonly black on most brake controllers) to the 30 pin on the relay.

This should allow normal electric brake controller function when using the brake pedal and when only using the manual slide on the controller with the exception of brake lights when using the manual slide on the controller. The relay will prevent the controller from sending a brake light feed back to the vehicle.

I can draw a diagram if anybody needs it but not on this ipad.

That's what the trailer guy said. He is asked for the failed part and are going (together with the brake ctrl company) back to Toyota to have them explain how their "factory feature" doesn't work.

I would also like to hear Toyota's explanation for this. We shouldn't need to add a relay. This has been plug and play for years.

 

[brian0128]

Should be easy. Just get a SPDT (single pole double throw) relay. You want to interrupt the brake switch signal wire (commonly red on most brake controllers). With the brake signal wire cut, attach the wire coming from the vehicle to the 86 pin on the relay. The cut wire coming from the brake controller will go to the 87 pin on the relay. Now, connect a jumper wire from the ground wire (commonly white on most brake controllers) to the 85 pin. Next connect a jumper wire from the 12v supply wire ( commonly black on most brake controllers) to the 30 pin on the relay.

This should allow normal electric brake controller function when using the brake pedal and when only using the manual slide on the controller with the exception of brake lights when using the manual slide on the controller. The relay will prevent the controller from sending a brake light feed back to the vehicle.

I can draw a diagram if anybody needs it but not on this ipad.

What's the difference in wiring in a diode or a relay? Same procedure?

 

[gm350reratliff]

What's the difference in wiring in a diode or a relay? Same procedure?

The difference in wiring would be only the brake switch wire (commonly red on most brake controllers) would need to be cut and the diode installed inline with the anode towards the truck side and the cathode towards the brake controller. You would just have to figure out which diode to use. I would be afraid that, in the event of having to use the manual slide on the controller a lot, a bunch of heat could be generated. The other issue is, there is sometimes a small amount of reverse current that a diode can let by so it may not be completely effective. Those two reasons alone are why I suggest using a relay instead.

 

[1engineer]

I am not an electrical engineer nor do I have a trailer brake installed. I have however read most threads here discussing the trailer brake and I do not recall anyone mentioning having to install a relay or a diode. Here are some links:
http://www.toyota-4runner.org/5th-gen-t4rs/71991-has-anyone-wired-trailer-brake-control.html
http://www.toyota-4runner.org/5th-gen-t4rs/86610-trailer-brake-controller-installation.html
http://www.toyota-4runner.org/5th-gen-t4rs/97192-help-travel-trailer-braking-system-towing.html

Hope this helps you guys....

 

[gilpinbrewer]

Here is the Wiring diagram for the brake controller hookup. This may help.

 

[gm350reratliff]

Here is the Wiring diagram for the brake controller hookup. This may help.

Thanks.

Looking at the diagram on page 3 shows there should be a diode in place to prevent this nonsense. Maybe a bad run of diodes in some 4Runners?
[MENTION=66316]1engineer[/MENTION] is right. This is something new as nobody has ever had this issue before and had to install an extra relay or diode.

**Before we go any farther, I would like to say that adding a relay or diode inline should be considered a band-aid until a real fix from Toyota is released. Yes, the extra relay will work but something else is at fault here. Again, the one main issue when adding a relay like I described a page or so back is, when using the manual slide on the controller the brake lights will not come on because the relay is interrupting that circuit to prevent feed back to the vehicle. The brake lights (and brake controller) will still function as normal when using the brake pedal.

 

[TOY2G]

I'm a fan of the Hopkins Flex Mount. it makes it much easier to mount a controller and not have it look like-a da-poo-poo in the cabin.

I have the flex mount in 3 of our 4 tow capable vehicles, and it does not affect the ABS or Track lights on any of them, including the Lexus.

 

[fubar]

Truck back from the dealer without all the blinky lights. Yaw controller replaced and the dealer installed the Prodigy 2 *WITHOUT* adding a relay or diode. Same tech, different story today.

*sigh*

I have not tested it with the trailer attached, but so far so good.

 

[pbcolt]

Truck back from the dealer without all the blinky lights. Yaw controller replaced and the dealer installed the Prodigy 2 *WITHOUT* adding a relay or diode. Same tech, different story today.

*sigh*

I have not tested it with the trailer attached, but so far so good.

Let us know what happens when you hook up the trailer and use the manual slide.

 

[fubar]

Test with trailer. Initial results good...for about a mile.

I used the manual override several times to calibrate the brakes. All seemed fine. About a mile in, while *not* using the manual override, the ABS/VSC lights came on. Fortunately the errors were not persistent and the lights were fine when I turned the truck off-on.

V-mail to the Toyota Service Adviser for explanation.

:wtf:

 

[be77solo]

Thanks for keeping us posted! Definitely curious to see this resolved... so far I've towed without breaks but will need to do so soon, have a controller w/harness sitting in glovebox waiting to install until I see what's up with this thread.

 

[brian0128]

My dash lights went out after 3 days of not towing. I hooked the trailer up and tried the manual brake overide and the lights are back on again. I tried turning the engine off then on but it didn't clear the lights. Once the lights clear then I'm going to try out a friends controller from his 2010 SR5.

 

[hamlet]

Running with a P3 and have the same issue. I suspect, as others have, that it's the ground wire that needs a good mounting location. Have yet to find a good one, obviously the one I used is not a good ground... Having said that, it's seems to be a Toyota thing as others don't need to run a separate ground wire if using the factory plug.

Now, for all those with the lights coming on when using the manual braking lever, are you able to lock up your trailer wheels (regardless of the dash lights coming on)? I have yet to succeed, even with a high voltage setting on the P3, which makes me suspect that it's a grounding issue.

 

[fubar]

I was also not able to lock the brakes at full boost.

Will check ground too...

 

[brian0128]

Running with a P3 and have the same issue. I suspect, as others have, that it's the ground wire that needs a good mounting location. Have yet to find a good one, obviously the one I used is not a good ground... Having said that, it's seems to be a Toyota thing as others don't need to run a separate ground wire if using the factory plug.

Now, for all those with the lights coming on when using the manual braking lever, are you able to lock up your trailer wheels (regardless of the dash lights coming on)? I have yet to succeed, even with a high voltage setting on the P3, which makes me suspect that it's a grounding issue.

I was not able to lock the trailer wheels and I ran the ground wire to a decent looking grounding point. I will see if I can switch ground locations tonight and see if it makes a difference.

 

[itsdchz]

Just a thought... Why does the Toyota version have that second white ground wire? There is a ground already within the factory connection, and a ground wire is also ran in the wire harness that goes from the P3 to the Factory connection?
Has anyone tried not connection that second ground wire? Are we double grounding or causing some type of "short"? Why is the second white ground necessary? I have moved the ground mounting point of the white, secondary ground, twice and still have the VSC and ABS light fire when manual braking.

 

[brian0128]

Just a thought... Why does the Toyota version have that second white ground wire? There is a ground already within the factory connection, and a ground wire is also ran in the wire harness that goes from the P3 to the Factory connection?
Has anyone tried not connection that second ground wire? Are we double grounding or causing some type of "short"? Why is the second white ground necessary? I have moved the ground mounting point of the white, secondary ground, twice and still have the VSC and ABS light fire when manual braking.

I'm not sure but that's a good question. Do your VSC and ABS light go away if you restart the truck? Are you able to lock your brakes?

 

[Photi]

What are commonalities?

Just a thought... Why does the Toyota version have that second white ground wire? There is a ground already within the factory connection, and a ground wire is also ran in the wire harness that goes from the P3 to the Factory connection?
Has anyone tried not connection that second ground wire? Are we double grounding or causing some type of "short"? Why is the second white ground necessary? I have moved the ground mounting point of the white, secondary ground, twice and still have the VSC and ABS light fire when manual braking.

I'm very interested in this thread as I was about to install my P3 from another vehicle in my 2015 TEP.
In every case in this thread, where the model of brake controller was specified it was a Tekonsha P2 or P3. In every case it was also a 2014 or 2015 MY vehicle(I think) - therefore - is the problem an interaction between Tekonsha controllers and the 2014/15 instead of just being a Toyota problem?

Does anyone have a brake controller other than a P2 or P3 in their 2014/15 vehicle that is either failing or working properly?

Just a thought... I'd be happy to Ebay my P3 and get something that works properly and doesn't throw codes...

 

[fubar]

I checked the wiring done at the dealer for my Tekonsha P2 using the factory supplied harness. It does not seem to include an additional ground wire.

I have ordered the eTrailer harness mentioned earlier as that seems like the most likely solution.

 

[Carolina Roscoe]

I checked the wiring done at the dealer for my Tekonsha P2 using the factory supplied harness. It does not seem to include an additional ground wire.

I have ordered the eTrailer harness mentioned earlier as that seems like the most likely solution.

I ordered and installed the the E-trailer harness and the P3, I still got the error.:shrug: