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I have tried this several different times and different ways, but I can't get it to work. I can't for the life of me figure how you got a small rectangle of electrical tape to stay on the male side of pin 11. Since this didn't work for me (I either couldn't get my hands in there to get the tape on or when I did the tape would not stay on when reconnecting), I tried using a small piece of wire insulation to cover the male side of pin 11. It of course just got pushed back and apparently didn't do the job either. Then I just "pushed" e pin 11 aside with a samll screwdriver so that it would not slide into the female end, and there is no way there was a connection being made. But I still could not get both ATRAC and RR lock to engage SO, I thought I had a bad T-splice because the splice was for a 16-14 GA and the wire is more like a 22-18 GA. I finally tracked down a smaller T-Tap from NAPA this morning (18-14) and it seems to be making the "bite" into the insulation. NOW, the ATRAC won't even come on at all, but the RR Diff lock will. I have no connection on the pin 11 (because it's pushed aside), and I have a +12v to the wire coming out of the female side of pin 11 to the fusebox.

When I re-straighten pin 11, I get my ATRAC back, but still no simultaneous engagment of ATRAc and RR lock/

What the heck am I doing wrong?

In the midst of my frustration this weekend I managed to hook up my new Warn dual beam lights, but I cannot rest until I get this hack right.

Please help.
 

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Discussion Starter · #42 ·
I have tried this several different times and different ways, but I can't get it to work. I can't for the life of me figure how you got a small rectangle of electrical tape to stay on the male side of pin 11. Since this didn't work for me (I either couldn't get my hands in there to get the tape on or when I did the tape would not stay on when reconnecting), I tried using a small piece of wire insulation to cover the male side of pin 11. It of course just got pushed back and apparently didn't do the job either. Then I just "pushed" e pin 11 aside with a samll screwdriver so that it would not slide into the female end, and there is no way there was a connection being made. But I still could not get both ATRAC and RR lock to engage SO, I thought I had a bad T-splice because the splice was for a 16-14 GA and the wire is more like a 22-18 GA. I finally tracked down a smaller T-Tap from NAPA this morning (18-14) and it seems to be making the "bite" into the insulation. NOW, the ATRAC won't even come on at all, but the RR Diff lock will. I have no connection on the pin 11 (because it's pushed aside), and I have a +12v to the wire coming out of the female side of pin 11 to the fusebox.

When I re-straighten pin 11, I get my ATRAC back, but still no simultaneous engagment of ATRAc and RR lock/

What the heck am I doing wrong?

In the midst of my frustration this weekend I managed to hook up my new Warn dual beam lights, but I cannot rest until I get this hack right.

Please help.

Ok, let's see if we can this this working. These are basic troubleshooting questions and should not be taken the wrong way. :)

1) Are you sure that you are working with connector LA2 and not LA3?

2) Are you sure you are working with the correct side of the connector? If you are applying +12V to the differential side of the wire instead of the ECU side of the wire, I would expect to see the issue that you are reporting. The ECU must see +12V on this line to engage A-TRAC.

3) Are you sure that your newly tapped line is actually at a constant +12V with the truck running? Make sure the fuse you connected it to is not switched/blown.

A general rule in this circuit is this: If A-TRAC will NOT come on, then there is no +12V present on the sensor line.

Just as an FYI: The last truck I did, I used a small bit of heat-shrink tubing (rather than tape) that was the about the same OD of the pin. I hit it with a heat gun/hair dryer to shrink it onto the pin, leaving a mm or so to fold over. Worked like a champ.
 

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Thanks for the response. I was wondering if maybe I sent a code with all my trial and "errors" and perhaps I need to reset? I saw someone doing this on another post (might have been Alex).

Anyway, in response to your questions:
1) Yes, I am certain about LA2. It has 11 pins, and the blue/yellow one is in the top left position as I recall, right? (please say right).

2) From looking at the pictures posted I THINK I've got the splice on the correct side, but now you have me thinking. I have it on the female side of the LA2 connector (closest to me vs. the male side being closest to the firewall). Please say I'm wrong on this and then I'm just an idiot but that would solve everything.

3) I connected the tapped line to the exact same one in the picture posted (top row, second from left- between two existing fuses).

I really like the heat shrink tubing idea. I will try that but I'll wait for your responses to the above before I make the next move.

I appreaciate your help on this...I'm headed to Telico this weekend and I would love to have this working to compare from my last trip on the same trails.

FJC
 

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Discussion Starter · #44 ·
Thanks for the response. I was wondering if maybe I sent a code with all my trial and "errors" and perhaps I need to reset? I saw someone doing this on another post (might have been Alex).

Anyway, in response to your questions:
1) Yes, I am certain about LA2. It has 11 pins, and the blue/yellow one is in the top left position as I recall, right? (please say right).

2) From looking at the pictures posted I THINK I've got the splice on the correct side, but now you have me thinking. I have it on the female side of the LA2 connector (closest to me vs. the male side being closest to the firewall). Please say I'm wrong on this and then I'm just an idiot but that would solve everything.

3) I connected the tapped line to the exact same one in the picture posted (top row, second from left- between two existing fuses).

I really like the heat shrink tubing idea. I will try that but I'll wait for your responses to the above before I make the next move.

I appreaciate your help on this...I'm headed to Telico this weekend and I would love to have this working to compare from my last trip on the same trails.

FJC

Everything sounds right.

Check for +12V on the tap on the ECU side with a meter. This can be done by taking a SMALL piece of wire and stripping off ~2" of insulation. Insert the stripped side into the ECU side of the connector and let the other side hang loose. Re-assemble connector.

The friction of the connector will keep the wire in place long enough for you to use it as a probe to determine the voltage to the ECU.

If you get +12v here, try a reset.
 

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Thanks. I'll try that.

I was wondering...(dangerous, I know) What if I were to just cut the blue/yellow wire coming into the female side of LA2 and connect it directly to the +12v source/fusebox? This would not be my first choice because it's less reversable, but in theory would that work?

OR, just pull the female side of the pin out of the connector and connect it to the +12v source. How difficult would it be to pull that thing out?

Forget I asked that. I found a similar question on the previous thread.
 

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Discussion Starter · #47 · (Edited)
Thanks. I'll try that.

I was wondering...(dangerous, I know) What if I were to just cut the blue/yellow wire coming into the female side of LA2 and connect it directly to the +12v source/fusebox? This would not be my first choice because it's less reversable, but in theory would that work?

OR, just pull the female side of the pin out of the connector and connect it to the +12v source. How difficult would it be to pull that thing out?

Forget I asked that. I found a similar question on the previous thread.
Cutting anything negates one of the two benefits of my version (no cut, inside the cab). If you are ready to cut, just do the Alex mod as it is easier and takes a total of 5 minutes.

EDIT: Yes. That would work. At least your cut would be inside the cab of the truck rather than under the hood.
 

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SS555,

I appreciate your lengthy research and write up on this subject.

Thanks for answering my questions. I will be trying this out again tonight, so I hope to report success tomorrow.
 

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Discussion Starter · #49 ·
If anyone has a clue as to the (electrical) drive type in the rear diff sending unit, I'd like some details (I'm not tearing into mine again for at least a week...I promised the wife!).

What I am thinking is if the +12V sent by the rear diff sending unit is not source driven, but is a result of a pullup/pulldown, then one could skip isolating pin 11 altogether, and just insert the tap wire directly into the LA2 junction with a 1K Ohm resistor inline to the fuse box. This would make this mod a complete joke to do and would do away with the need for a tap at all. No cutting, no tapping, just a 1K Ohm resistor and a piece of wire routed to the fusebox.

Example:
LA2: Pin 11 junction ------------------MMM----------------Fusebox.


(MMM = 1K Ohm resistor. ------- = wire)


This would serve to keep the diff line at +12v all the time, and the resistor would prevent a dead-short when the rear diff sender drives low.

Anybody?
 

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Tapping a resistor to 12v there would have no effect- it would still be connected to ground by the Rear Diff Lock Indicator Switch.

Here is a simplified wiring diagram of that circuit showing where we are hacking the wiring:



The 12v input signal to the Skid ECU comes through the Diff Lock Indicator LED in the combination meter and is grounded at the Rear Diff Lock Indicator Switch. The Skid ECU is simply monitoring the presence (or absence of) 12v on this circuit. This is why we need to isolate the Skid ECU from the circuit and then supply 12v to it.


Why don't you just back the male pin out of connector LA2 and connect it to 12v? The pin is a lot easier to remove than you think. Pop the secondary release up like this:

You can use a steel scribe, the tool pictured is the recommended one but a scribe will also work.


Then pull up the tab inside the connector housing while tugging on the light blue/yellow wire. The pictured housing has female terminals, the male connector housing has a lot more room to work.


Simply connect the removed wire to 12v, insulate well and you are done. No cutting and it is easily reversible. Taping over the male pin and reconnecting it will stretch out the female pin. It wouldn't have a very reliable connection if you ever wanted to return it to factory condition, and seems to be difficult to do correctly.

Thanks for doing the hands-on research for this mod! I was originally thinking of doing it here as opposed to in the engine compartment. The wiring at the Skid ECU is so much more accessible I figured it would be easier to tell others how to do it as I still haven't even sat in an FJ Cruiser.
 

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Discussion Starter · #51 · (Edited)
Tapping a resistor to 12v there would have no effect- it would still be connected to ground by the Rear Diff Lock Indicator Switch.

Here is a simplified wiring diagram of that circuit showing where we are hacking the wiring:



The 12v input signal to the Skid ECU comes through the Diff Lock Indicator LED in the combination meter and is grounded at the Rear Diff Lock Indicator Switch. The Skid ECU is simply monitoring the presence (or absence of) 12v on this circuit. This is why we need to isolate the Skid ECU from the circuit and then supply 12v to it.


Why don't you just back the male pin out of connector LA2 and connect it to 12v? The pin is a lot easier to remove than you think. Pop the secondary release up like this:

You can use a steel scribe, the tool pictured is the recommended one but a scribe will also work.


Then pull up the tab inside the connector housing while tugging on the light blue/yellow wire. The pictured housing has female terminals, the male connector housing has a lot more room to work.


Simply connect the removed wire to 12v, insulate well and you are done. No cutting and it is easily reversible. Taping over the male pin and reconnecting it will stretch out the female pin. It wouldn't have a very reliable connection if you ever wanted to return it to factory condition, and seems to be difficult to do correctly.

Thanks for doing the hands-on research for this mod! I was originally thinking of doing it here as opposed to in the engine compartment. The wiring at the Skid ECU is so much more accessible I figured it would be easier to tell others how to do it as I still haven't even sat in an FJ Cruiser.
Damn! I knew it had to be too easy.


I took a good hard look at the LA2 connector with the thought of just pulling the pin (which I agree would be the preferred way), but was unsure about how the release worked. I was afraid that once I did the release, ALL the wires would come out. :) It's nice to know that there is a secondary release.
 

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I still haven't even sat in an FJ Cruiser.
Well, if you had stayed out here longer when you were out here a few days ago you could have! :D
 

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O.K. now I'm confused...but that shouldn't surprise you. You 2 are obviously electrical engineers or something and I am trying to keep up.

In previous posts I thought you had said supply the +12v to the female side of LA2 connector. Now are you saying I should apply the +12v from the fuse box to the male side of this connector?

Sorry if I've missed something but I don't want to screw something up.

Thanks
 

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Discussion Starter · #54 ·
O.K. now I'm confused...but that shouldn't surprise you. You 2 are obviously electrical engineers or something and I am trying to keep up.

In previous posts I thought you had said supply the +12v to the female side of LA2 connector. Now are you saying I should apply the +12v from the fuse box to the male side of this connector?

Sorry if I've missed something but I don't want to screw something up.

Thanks
Just hang loose for a few more hours. I'll redo the main post with an even easier method that requires nothing but a length of wire.
 

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Cool...

The other way seemed like a lot more work to me than snipping the wire under the hood.

Still, fishing out that wire from the plastic plug scares me a bit.
I have worked with wiring for years in vehicles, but never attempted to dissect a plug like that before.
 

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Discussion Starter · #56 ·
Cool...

The other way seemed like a lot more work to me than snipping the wire under the hood.

Still, fishing out that wire from the plastic plug scares me a bit.
I have worked with wiring for years in vehicles, but never attempted to dissect a plug like that before.
It's not as hard as it sounds. It used to take me longer to do the T-splice that it does to remove this wire from the connector.
 

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Well, if you had stayed out here longer when you were out here a few days ago you could have! :D
Dang it! The closest I got was driving a Corolla rental while listening to Jeff talk about how much he LOVES his Jeep!

Procedure has been updated with all new pictures and new instructions based on input from Alex.
Great writeup and photos Superstar! I always thought that this was the way the FJ Cruiser should have been built. Everyone should be able to do it one way or another now.
 

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Discussion Starter · #59 ·
Dang it! The closest I got was driving a Corolla rental while listening to Jeff talk about how much he LOVES his Jeep!



Great writeup and photos Superstar! I always thought that this was the way the FJ Cruiser should have been built. Everyone should be able to do it one way or another now.

You were right about the RR Diff Switch also grounding the signal...

Ask me how I know. ;)

How long does the burning wire smell last?

:stickpoke:

(Everything is A-OK)
 

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BRILLIANT! Kudos to SS555 and Alex. I've got it working and I will be testing it thoroughly this weekend at Telico trails 4, 5 & 6.

I thought it was just my imagination about the burning wire smell!

Thanks
 
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