Re-Examining the A-TRAC + RR DIFF LOCK Hack...

[superstar555]

Guys, I think there is a better way to do this than cutting the wire entering the 4WD ECU, and the answer is on page 190 of the wiring diagram...Junction L20.

I need to look at it a bit more, but I am thinking something along the lines of a "skip shift" eliminator where a dummy plug that isolates pin 8 and at the same time taps +12V to pin 11 (jumpered from another line in the same connector) is inserted in-line of the factory harness. All other lines would pass thru the connector as normal, and if push came to shove on a warranty issue, the in-line adapter is easily removed.

Isolating L20:P8 is easy, but I need to actually get under the truck with a meter looking for a constant source of +12V on L20; I'm betting there is at least one.

Am I missing something here?

[PRCruiser]

man, if you are a geek in electronics try to figure out how to activate the atrac when the Fj is not equipped with it and rear locker... I bought the button but nothing happens.

[highbeams]

the wire you t splice is a constant 12 volt
so snip and splice and it is doen in 2 minutes, or check poke and find an easier way spending more time

[Tranman]

Superstar, Alex's wire mod is pretty easy already. If you can find an easier way, go for it! Good luck finding advice. What you said went WAY OVER my head.

When you figure it out, do let us know. Good luck.

[Hwtrader]

PRCruiser previously said:

man, if you are a geek in electronics try to figure out how to activate the atrac when the Fj is not equipped with it and rear locker... I bought the button but nothing happens.

Simple! Just pull the master cylinder, ABS module, computer and sensors off a locker equipped FJ and drive yours underneath.

[utah tojo]

superstar555 previously said:

Guys, I think there is a better way to do this than cutting the wire entering the 4WD ECU, and the answer is on page 190 of the wiring diagram...Junction L20.

I need to look at it a bit more, but I am thinking something along the lines of a "skip shift" eliminator where a dummy plug that isolates pin 8 and at the same time taps +12V to pin 11 (jumpered from another line in the same connector) is inserted in-line of the factory harness. All other lines would pass thru the connector as normal, and if push came to shove on a warranty issue, the in-line adapter is easily removed.

Isolating L20:P8 is easy, but I need to actually get under the truck with a meter looking for a constant source of +12V on L20; I'm betting there is at least one.

Am I missing something here?

I've also been thinking along the same lines. Wish I had one to figure it out. One of these days. We owe the guy who figured it out alot. Being in electronics I hate the idea of cutting or stripping insulator where corrosion can get in.

[superstar555]

I have finalized my suggested alternative "No Cut" solution.

Behind the driver's side kick-panel lurks connector LA2.



1) Disconnect the battery.
2) Remove the kick panel.
3) Disconnect LA2. See FJ Wiring Diagram for location.




4) Isolate Pin 11 of connector LA2 (refer to page 285 in the FJ Wiring Diagram) on the Differential (female) side of the connection. A small piece of electrical tape works.
5) Short Pin 4 to Pin 11 (page 285 again, male side of the connector, 4 sits on top of 11) with a small piece of bare wire. The friction of the connector will hold the wire in place. This provides the constant +12V to the 4WD ECU. **SEE NOTE** This doesn't work on all FJs. See SASUVs post further down in this thread for details.
6) Re-assemble and enjoy A-TRAC + RR DIFF without any cutting or permanent modification. To return to stock, just remove the jumper and tape.


NOTES:
1) This may not work if you don't have the trailer towing package since LA2 : Pin 4 is the left tail light power supply for a trailer. Someone without a towing package needs to verify +12V on LA2 : Pin 4.

I'll try to photo-document the procedure this weekend if I have time.


EDIT: PERFORM THIS AT YOUR OWN RISK. UNDERSTAND WHAT YOU ARE DOING BEFORE YOU BEGIN!!!

[superstar555]

Tranman previously said:

Superstar, Alex's wire mod is pretty easy already. If you can find an easier way, go for it! Good luck finding advice. What you said went WAY OVER my head.

When you figure it out, do let us know. Good luck.

I agree that his mod is easy, I just wanted to avoid cutting a wire, especially one located in the engine compartment.

He blazed the trail, I just paved it.

[Tranman]

Dude, I have no trailer pkg. Post the pics and I will give your mod a try. I have no idea what I am doing but your thought process seems reasonable. Plus it's reversible right?

[Zurn]

Pictures for us wireing diagram challenged people would be sweet! I am also a bit concerned about cutting wires so if this works, I’m in…