04 LX470 AHC, brake controller, & Electrical Issues Question (2 Viewers)

[westwardCruiser]

I just put this in my 04 LC and it seems like the VSC lights and the backfeeding (I noticed my fan would blow prior) has stopped, but when I went to lock the truck with the key fob it did nothing. Removed the wire harness and it worked fine.

I don't remember that being an issue before, but then again I usually pulled the harness every time I stopped.

Anyone else out there with an 04 have any input on how this worked out for them?

 

[SICARIO]

Adding a relay to the system is the right way prevent backfeeding. However, the relay that Toyota provides is wired incorrectly. They put a splitter on the 12v line and ran it to both sides of the relay, so the relay stays stuck on even after you turn the vehicle off.

The fix: you have to remove the wrapping from the wiring harness and identify the wire going to the signal side of the relay. That needs to be wired to a separate 12v keyed power source. I wired mine in to the accessory 12v outlet. There’s no worry of overloading that outlet since the signal side of the relay pulls a very low amperage. I also took the opportunity to redo all of the spliced connections on the harness with solder and shrink type (they used a crimp connection with electrical tape)

This finally fixed my backfeedubg issue.

If my description doesn’t make sense, I’ll pull mine apart and identify the wire that needs to be cut and relocated.

Hope this helps

 

[westwardCruiser]

Adding a relay to the system is the right way prevent backfeeding. However, the relay that Toyota provides is wired incorrectly. They put a splitter on the 12v line and ran it to both sides of the relay, so the relay stays stuck on even after you turn the vehicle off.

The fix: you have to remove the wrapping from the wiring harness and identify the wire going to the signal side of the relay. That needs to be wired to a separate 12v keyed power source. I wired mine in to the accessory 12v outlet. There’s no worry of overloading that outlet since the signal side of the relay pulls a very low amperage. I also took the opportunity to redo all of the spliced connections on the harness with solder and shrink type (they used a crimp connection with electrical tape)

This finally fixed my backfeedubg issue.

If my description doesn’t make sense, I’ll pull mine apart and identify the wire that needs to be cut and relocated.

Hope this helps

Thanks, I don't think I've seen that explained before! What a major PITA, it's unfortunate they got it wrong twice.
I'll give it a try when I get some time and let you know if I get completely stuck. Hopefully I can get some pictures without you tearing into yours.

 

[skivan]

Thanks, I don't think I've seen that explained before! What a major PITA, it's unfortunate they got it wrong twice.
I'll give it a try when I get some time and let you know if I get completely stuck. Hopefully I can get some pictures without you tearing into yours.

Thanks, I don't think I've seen that explained before! What a major PITA, it's unfortunate they got it wrong twice.
I'll give it a try when I get some time and let you know if I get completely stuck. Hopefully I can get some pictures without you tearing into yours.

Following these updates -- i just put the relay in my 04 LC in prep for our first time out with the trailer this year, but it's still giving me the VSC dash light when my trailer is plugged in and then truck started (trailer has a battery that's backfeeding i assume). no brake controller but with the relay installed and 7 pin hooked up my key fob didn't work either.

I don't know which of the wires would be the powered wire to the "signal side of the relay" but would be stoked if you took a look and reported back Sicario. thanks very much for figuring that out. @westwardCruiser did you figure yours out? i think we're in the same boat. happy camping.

 

[SICARIO]

I’ll try to open it up tomorrow and take some pictures.

 

[westwardCruiser]

I might actually get to it this weekend. I leave to go camping on 6/2, so that is my incentive!

@SICARIO would it be easier for you if I took some pictures of mine and you just identified which wires to cut?

 

[skivan]

i had a few minute and went to take a look. The relay is a Denso 156700-2470, and the diagram is below. i think what you're saying (forgive me for being slow) is that the 'signal' wire needs to be connected to a keyed dc source (like the 12 v accessory right next to it), so that the switch is on once keyed. then current from the trailer can't flow back to the truck once the switch is off. so looking at the diagram, i assume you used the 'signal' position on the relay and connected that to the hot side of the 12v accessory. This is the black/white wire on the harness. There are 3 other wires -- black ground (positions 2), black battery (position 3) and blue output (position 4).

thanks for any comments, and hope i saved you the digging.

 

[SICARIO]

The black wire was the 12v in. That is the one I cut and ran to the 12v socket. I tested it out last weekend with our first trailer camping trip, worked perfectly.

 

[westwardCruiser]

I think I'm in business, I jammed a ~20 gauge hookup wire into the 12v wire harness and soldered the other end to the black wire. No VSC lights or evidence of flow back. And my doors lock! I think I'm in the clear.

The green wire is the + wire for the 12v outlet.

Thanks so much @SICARIO

 

[taco47001]

@SICARIO @westwardCruiser
I juts want to make sure I'm understanding correctly, one needs to cut the black wire shown. Which end gets attached to the 12v keyed source? The wire going to the relay shown or the other end? I'm assuming the one going TO the really but I'd hate to be wrong and and up frying something very important. Thank you in advance.


Edit: I went ahead and wired the 12v keyed signal to the relay wire as shown. Boom! Finally no more electrical demons from travel trailer backfeed.

 

[tw22]

I might need some help with this when my relay part # PN-82241-60100 arrives.
Still not quite following what needs to be done for install.

Maybe it will make more sense once I start looking at the part.

 

[outdoor7or24]

Where is this relay located? I looked in my drivers side rear cargo, pulled out the jack and tools, I did not see it.
Should I take the metal plate for holding the jack out to find this relay?
2005 LX is my model.

I hooked up my Prodigy P3 with plug n play harness (it was a little harder than plug and play) and it seems to work okay. However I do not want to have electrical issues...

The black wire was the 12v in. That is the one I cut and ran to the 12v socket. I tested it out last weekend with our first trailer camping trip, worked perfectly.

View attachment 1707889

 

[tw22]

I haven’t installed the relay yet either in the back of my truck existing wiring is tucked behind the tail light corner . See picture. However there’s two plugs.

I’m not sure which one to disconnect to connect the relay inline.,? Anyone have any ideas?

 

[SICARIO]

I haven’t installed the relay yet either in the back of my truck existing wiring is tucked behind the tail light corner . See picture. However there’s two plugs.

I’m not sure which one to disconnect to connect the relay inline.,? Anyone have any ideas?

View attachment 1934657

It looks like the relay is already installed. Disconnect both blue plugs and what you remove is the relay with associated wires. Follow my instruction on fixing the wiring on it and you should be in business.

 

[Ray J]

Totally going to try this! I've had this issue sporadically as well. Other than pulling from the battery to the vehicle, any long term problems if it goes uncorrected, using the unplug it method

 

[Asanka]

Part 8224160100 is discontinued, and I'm having the same issue. Are those plugs available to buy to DIY the relay?

i had a few minute and went to take a look. The relay is a Denso 156700-2470, and the diagram is below. i think what you're saying (forgive me for being slow) is that the 'signal' wire needs to be connected to a keyed dc source (like the 12 v accessory right next to it), so that the switch is on once keyed. then current from the trailer can't flow back to the truck once the switch is off. so looking at the diagram, i assume you used the 'signal' position on the relay and connected that to the hot side of the 12v accessory. This is the black/white wire on the harness. There are 3 other wires -- black ground (positions 2), black battery (position 3) and blue output (position 4).

thanks for any comments, and hope i saved you the digging.


View attachment 1707799

 

[bgriest]

Part 8224160100 is discontinued, and I'm having the same issue. Are those plugs available to buy to DIY the relay?

I just picked up an off-road trailer with battery yesterday. I have all the symptoms, rear wiper, VCS lights, electric locks. Anybody source the part or is there another solution?

 

[bgriest]

Obviously took me a while to get around to it, but with all the direction and pictures I was able to take care of the trailer battery return issue. Thanks to all the contributors of this thread. I'm an electrical idiot and this was an intimidating project for me. Splice into green, cut and connect black. That much I can do. Just had to get it straight in my head and locate the proper wires. I plugged the trailer in before putting everything back together with no symptoms. Fingers crossed. It was driving me crazy.