Transmissions / Transfer Cases / Traction AidsThis area is for discussion, questions and problems with the FJ Cruiser's gear train, including topics on A-TRAC, VSC, locking diffs, gear ratios, manual vs. AT, etc.
this thread is great .. thanks bugs for directing us kids lost in all the other crazy threads on this topic... you boys are a becon of hope for the people that dont have time to figure it out on their own.. THANK YOU!
Kat.
Hey, no problem! I started to read the thread you started but was overwhelmed by all the negative vibes, so to speak. I have used my VSC/TRAC cancel switch on several occasions where I knew the truck would get fooled by one tire momentarily slipping, like sand along the edge of the street (from all the snow we have been having--sanded roads). You have to pull out from businesses into 45mph traffic and there isn't usually a big opening so you pretty much have to be aggressive. The TRAC can be very unnerving trying to get into traffic and the FJ just won't go. Good luck with everything.
Bugs
Here is what I have on file (I am back at home, with my perma-FJ files). This is the full write-up and probably known formerly as the "cut A-TRAC hack"
A BIG BIG BIG thanks to Alex H., he did all the study and theory behind it, working with the elec diagrams and logic flow of the FJ's systems - and he doesn't even have an FJ!! . I'm just the lab rat who was crazy enough to try it first. So yes, I now can have both the ATRAC system and the rear locker on at the same time, or just ATRAC, or just rear locker, or none of the above.
Ok, on to how to do it!!.. First off, do this at your own risk, yes this could void your warranty, no don't do it if you have no idea what you are doing, and nobody is responsable if you screw it up or anything else!! But if you want to use the rear locker and ATRAC at the same time, read on!
This is the master cylinder, with the VSC computer on the side of it. For those with service manuals and/or electrical diagrams for the FJ, the large connector with all the wires is A4, the smaller one is A5.
This is the wire you are looking for - it's blue/yellow. It's pin 26 on the connector, in the electrical diagrams it's terminal EXI3.
You want to cut the blue/yellow, leaving a good amount of length. You then want to take the connector side of the blue/yellow, and using a T-junction or tap, connect it to the Black/orange wire on connector A5 (pin 1). You do not want to cut the black/orange, just tap into it. The remaining blue/yellow in the wire harness just tie away inside the harness, do not ground it or connect it to anything.
That's it! You now can use ATRAC with the rear locker. Damn that was simple wasn't it?
Ok, the theory behind it (all via Alex). The blue/yellow wire is a signal wire from the rear locker (actualy it's from the dash light circut). When the locker is off, this wire has +12v, telling the VSC computer that the locker is off and it can use ATRAC. When the locker is locked, this wire has 0v, telling the system the locker is locked and then it won't let ATRAC turn on. All we have done is take the wire, and tap it into the 12V acc power on connector A5. This tells the VSC computer that the locker isn't on, all the time, even when the locker is on. This doesn't affect the locker light or any of the other lights or system. It just fools the VSC computer into thinking the locker is off all the time.
ATRAC works by sensing wheel spin on each axle. If it senses one wheel on an axle spining faster than the other, it applies brake to that wheel to lock it and transfer the power to the other wheel. Since the rear is locked, one wheel on that axle can't spin at a diffrent speed than the other, so the ATRAC system never activates on that axle, it ignores it. It will then only activate on the front if it senses one wheel spining up there.
And some more.....
To answer the original question, you can disable all skid-control features (VSC,TRAC,ATRAC,ABS) if you disconnect the rear-difflock-switch-position wire, which is located at connector A4, pin 26 (light-blue/yellow wire). This will cause the skid control ECU to think the rear diff is locked all the time. Simply put a switch on this wire and you can disable all skid-control features whenever you want, at your own risk. (side note: this does not interfere with the ability to lock the rear diff.)
Clear as mud (or is that mod)?
The pic's, you already have....
Thanks to everyone who contributed to this mod.After alot of pondering I decided to go with this method.I just tried it out and it works great....Thanks dbbd1
Last edited by Toyota Pete : 02-18-2007 at 08:02 PM.
Hi.. i did the install and it works great.. just one thing though . is it common to need to turn the truck off and back on again in order to turn the vsc back on again?
So I started by unplugging the VSC and stripping the e-tape and cover to expose the wires.
Then I found access into the cabin through a removable grommit (careful I dropped it as it tends to pop out).
I cut the purple wire and spliced in 2 lengths of wire about 3 feet each and fed them through the hole. the backing you see in the hole is just the padding inside the cabin under the dash and can pull back easily.
I used a toggle switch as they are the easist to install, attach the wires and just drill a 1/2" hole then screw it in.
It's kind of hard to see here but I cut a small notch in the grommit before I replaced it so the wires could feed through. Clean up the wiring with some zip ties and some e-tape and you are all set. Let me know if you have any questions.
ok, i just did the mod and ofcoarse i absolutly love it. just one problem/question. if i turn the switch off and disable the VSC it all goes as it should the VSC disables itself, but after im dont having fun and i want to turn it back on i flip the switch back to the "on" position but the VSC stays off and wont re engage until i turn the truck off and back on.
is this normal, is it the same with you guys, or is something wrong????
thanks
~mike
__________________ ( O TOYOTA O )
THE FIRST EVER FJC COMMERCIAL!!!!
P.S. - the BD FJC wheelin in the first like 8 seconds with the tinted corner lights.....yeah.....thats me
I found the wire gray wire that the 4wd tells the Skid Control ECU to turn off VSC. I also found the white/blue stripe wire that turns off the slip indicator. These are the wires running into the Skid Control ECU. I took a pic of the two wires. Gray = VSC off, white/blue stripe = Slip indicator off. Grounding these wires takes the voltage away and in turn turns off the VSC or Slip indicator.
I also found that the gray wire runs to a connector just behind the glovebox if you would rather work with it inside the cab. The white/blue stripe wire is behind the gauge cluster. I couldn't get to that one.
I tried these and they did in fact work. When I removed the ground the system came back on without restarting the vehicle. I was going to add two switches, one for each wire. They would apply the ground when I turned on the switch.
I decided not to do this because when I turn on my locker from my locker mod, my VSC and my slip indicator turn off. That is what I wanted.
Hope this helps someone in their quest to customize. Do this at your own risk.
ok, i just did the mod and ofcoarse i absolutly love it. just one problem/question. if i turn the switch off and disable the VSC it all goes as it should the VSC disables itself, but after im dont having fun and i want to turn it back on i flip the switch back to the "on" position but the VSC stays off and wont re engage until i turn the truck off and back on.
is this normal, is it the same with you guys, or is something wrong????
thanks
~mike
I have a switch for the grey wire and it works well, disabling both VSC and TRAC but leaves ABS working normally. I posted how I did the mod back on post # 57. I also have to turn the engine off and restart to re enable VSC/TRAC.
Linear Mode
