A-TRAC Switch - Toyota FJ Cruiser Forum
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post #1 of 4 (permalink) Old 05-07-2006, 09:36 PM Thread Starter
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A-TRAC Switch

To read the original full thread and post questions/comments on this topic, please go to https://www.fjcruiserforums.com/forum...tall-pics.html

If anyone needs the background on adding the A-Trac option, please read through the previous thread: 2 cheap and easy A-TRAC hacks - Toyota FJ Cruiser Forum

Here's the process: 1. Remove the small cover under the parking brake. You can insert a screwdriver under the edge to pop it up - no screws.

2. Take out the rubber cup holder separator in the back of the center console and remove the 2 bolts with a 10mm socket.

3. Pull the top of the center console (around the shifters) straight up with your hands. It is held by clips and pulls up easily. Unscrew the 4wd shifter knob and pull the console top off. Put the shifter knob back on right away because the sharp threads of the shifter easily scratch the plastic panels!

4. Remove the two 10mm bolts on the sides of the console on either side of the (automatic) shifter. They are obvious, but I haven't seen them on a manual transmission model. Pull the console staight back away from the switch panel - no need to remove it.

5. Remove the 10mm bolts at the bottom of the switch panel and pop out the plastic retainers on each side. I didn't have a special tool, but if you push the center of the retainer clip straight in, you can remove the whole retainer.

6. Pull the switch panel out until you see the switches and wiring from behind.

7. At the A-Trac switch position, pull the switch blank out of the front. There will be a wiring plug connected to the back of the blank, but it may or may not be the correct one to connect to the switch. This threw me.

8. Push the A-Trac switch into the hole where the blank was removed and plug in the correct connector. The A-Trac connector has 4 wires running to it. Two of the wires are pink with a green stripe and white with a black stripe. I got confused because the connector in the location where the A-Trac switch goes had a pink wire with a blue stripe and a purple wire. I had a hard time seeing the black stripe on the white wire and the directions I read said to look for a black and white wire.

I can tell you this is easy and it works! I do not plan to try the hack which allows the A-Trac and locking diff to be active at the same time. It seems to be a lot more of a "hack" than simply adding a factory switch, and I'm not sure I understand the benefit at all.

I'll include some thumbnails in this post and then more in the next post.
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post #2 of 4 (permalink) Old 05-07-2006, 09:40 PM Thread Starter
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Re: A-Trac switch install with pics

more thumbnails...
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post #3 of 4 (permalink) Old 12-20-2006, 01:47 PM
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A-TRAC SWITCH: Simple installation video

To read the original full thread and post questions/comments on this topic, please go to https://www.fjcruiserforums.com/forum...diff-hack.html

I have received several requests to take the combined knowledge of my original post:


and place it in a seperate, and more easily read format. Original credit for the ECU hack goes to Alex, credit for the photos goes to SwissArmySUV.

This procedure was changed on 12/28 to remove the need for a wire tap. Some inline pictures were hyperlinked due to size.

PROBLEM: Early production 2007 model FJs (~pre-November 2006) do not allow A-TRAC to operate in conjunction with the Rear Differential Locker (RR DIFF LOCK) or vice-versa. The ECU allows only one or the other to be active, but not both.

WORKAROUND: Alex discovered a way to "fool" the ECU into thinking that the RR DIFF LOCK was always inactive by cutting the RR DIFF status wire coming from the rear, and applying +12v to it as it entered the ECU. From the ECUs perspective, +12v on this wire indicates that the RR DIFF is off. Since the ECU thinks the RR DIFF LOCK is off, it has no issues allowing A-TRAC to engage. Personally, I had issues cutting ANY wire on a factory wiring harness, much less one that is under the hood (exposed to elements) and connects to an ECU, so I looked for a different way.

SOLUTION After perusing the factory wiring diagram, I was able to track down the connector in which the RR DIFF signal joins the main engine compartment wiring harness. I surmised that by isolating this RR DIFF LOCK signal BEFORE it entered the engine compartment, I would be able to avoid cutting it at all. Subsequent testing has proven my theory, and I have modified 4 FJs (including my own) since then without cutting a single wire, or modifying the FJ in any way that is not 100% reversible. This modification is not difficult in the least, but DOES take a bit longer to accomplish than the Alex mod. Personally, I am able to complete it in less than 30 minutes, and for me, the extra effort is worth it for the benefits mentioned above.


Before we begin, here are the tools that are required:


Let's get a good look at the connector we will be utilizing:

Pay close attention to Pin 11. That is the ONLY pin we are concerned with.

Step #1: To get access to this connector, you must remove the driver's side the dead pedal, sill panel, and the driver's side kick panel. Location of LA2 is noted below:

Step #2: Once you have access to LA2, disconnect the battery (for safety), unplug the LA2 connector by pressing the white tab on the "passenger" side of the plug and gently pulling. Don't pull on the wires, pull on the plug itself.

Once you have the female plug out, you will need to remove the male side of the plug. This is held in by a small tab on the left side of the blue plug holder. Insert a wide blade screwdriver to dislodge the latch, and then gently push the "male" side of the connector out of the blue retaining structure (towards the firewall). You should now have the male side free:


Now that the "male" side of the connector is free, find pin 11 (it is blue with a yellow stripe). Once you know which wire you need, gently pry up the primary retainer mechanism on the top of the plug:


Once this is lifted, insert a small, thin, flat blade screwdriver in from the wire side of the connector, in-between the wire and the top of the connector. This should disengage the secondary retaining latch holding the wire in. Pull the pin out of the connector. It should come out easily.


Once the pin is out of the connector, go ahead and reconnect LA2. No tape or other isolation is required.

Take the newly freed pin and connect a length of wire to it. If you happen to have a female spade connector the right size, use it. If not, just wrap the wire around the pin several times to ensure a good connection. This is a low current application.


Now, tape up the connection.


Personally, I did not want to use heat-shrink tubing alone as it can be a PITA to remove later, so I taped first, and then used some tubing without shrinking it down all the way. Just enough to help hold things together.


Now, connect the other end of the wire to a +12V switched source:


Before re-assembling the trim pieces, now is a good time to make sure everything is connected properly. Turn on the truck, shift into L (1st), 4LO, and turn on RR DIFF LOCK and A-TRAC in no particular order, If everything is right you should see this:


If Toyota ever decides to retro-fit pre-November FJ's, just un-tape the pin, and reverse this procedure.

FAQ UPDATE 2/14/2007

"I accidentally connected the +12v wire to the wrong side of the circuit. Now my truck will not start"

Correct the hack, and check the 10A IGN fuse in the drivers side fuse panel. If blown (it is), replace it.
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post #4 of 4 (permalink) Old 01-05-2008, 05:49 PM
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A-TRAC SWITCH: Simple installation video

To read the original full thread and post questions/comments on this topic, please go to https://www.fjcruiserforums.com/forum...ion-video.html

I happened to have my camera while installing my A-TRAC switch today and figured I'd shoot a short "how-to' video while I was at it. This is literally one of the easiest items you can add to your FJ if you don't already have one.

This is easier to install than the '08 side visors!

Two quick things to remember:

1. Adding the A-TRAC switch is only for 4WD FJs with the locking rear differential.

2. A-TRAC will work with the locker up to 4 mph from the factory. No further modifications are required

Here are a couple of places to purchase the switch FJ CRUISER OFFROAD and TRD

SOLD - Integrated rear hitch receiver through a modified All-Pro rear bumper, Demello front bumper with Smittybilt XRC8 winch, Bilstein 5100 adjustables, Toytec rears with ProComps, Rasta front and center skids, Trail-Gear t-case skid, All-Pro high tuck tailpipe, Total Chaos Lower Link Skids, Harbor Freight hitch mounted disposable backup light, SCUBA mod...

Last edited by LandCruiserSteve; 03-21-2008 at 03:42 PM.
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