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Give me your tips for getting your rear diff to lock

5K views 25 replies 7 participants last post by  FFL1 
#1 ·
Hello All,
Just bought my 07 about 2 weeks ago. The rear diff wouldn't lock up when I was purchasing so I got them to knock 1100 off. They offered to fix it for me and leave the price as is, but I figured if I could get it working, I'll take the cash (which of course will immediately get spent in mods).

Well my gamble is not paying off yet. I've tried turning in circles, going forward, reversing, etc. but I can't get the locker to engage.

Does anyone have any tricks I could use to get this sucker to engage before I have to replace it?

Thanks a bunch
 
#2 ·
Its most likely the switch on the transfer case. Put it in Low & insure that all of the lights come on LL , VSC, ETC. IF they do not it is the low range switch on the T case. They are about 70$ and a PIMA to change. Look for the thread on this forum to disable the speed control & any speed rear locker. The Mod bypasses the switch & viola you have any speed locker, No speed control on your ATRAC & all of the electronic nannies go away with the push of the rear locker.
 
#4 ·
Pull the clip off the E locker at the rear axle & check to see if you are getting voltage to the actuator.
 
#5 ·
Drive in an "S" pattern, not a circle. (once you're in 4LO of course)
 
#8 ·
The clicking should be ATRAC, but if you have no switch I dont think it could be...which maybe isnt good lol. I do not believe it comes 'engaged' until you install the switch. Honestly, that is a question I am unsure of..
 
#12 ·
Sounds like you were in 4Hi not 4Lo... there should be no traction control or vehicle stability control enabled once you are in 4Lo. And since you don't have the ATRAC button we know that it was not activated.

Are you sure you are in 4Lo? If for some reason you were in 4Hi and thought you were in 4Lo, that would definitely give you some issues in trying to activate the locker.
 
#14 ·
Try it again and be 100% sure... it might be a "doh!" moment and everything is fine! :grin
(hopefully anyway!)
:cheers:
 
#15 · (Edited)
i want to be sure that i understand, the 4wd light stays on green and not blinking when in 4wd? the rear diff lamp is red and blinking? you are stopped when activating the rear diff lock switch? ( i realize the manual states under 5mph)


first disconnect the plug at the rear diff and see if its getting power. if it is then its the rear diff. if not then i would see if the 4wd lo switch is gummed up.
move the 4wd lever from 4lo to 4 high rapidly several times not fixed step 2
remove 4wd lo switch, squeeze, check continuity reinstall or replace depending on outcome.

the fj must be driven in 4wd monthly or things get gummed up.

the only clicking i've ever heard was from behind the glovebox just prior to the 4wd computer going bad.

also get the atrac switch and install it.


just my .02

lmk the what you find out.
 
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#18 · (Edited)
tools needed:
small bladed screwdriver
3/8 drive 1 1/16 crows foot
3/8 drive rachet
ohm meter


if it turns out the 4 lo switch needs to be removed do the research to get idea however you don't need to drop the t-case. you can't get access by removing the center console so, get it on ramps, get on your creeper and use the screwdriver to separate the wiring connector from the switch and the crows foot to loosen the switch. don't be timid to get on it and wear gloves. you will feel it break free then loosen the rest of the way by hand.
my hands are kinda big so i removed the heat shield first.
when you have the switch out just push/release the ball detent and check continuity. mine was so gummed up that when i pushed it i heard/felt it pop.
as it turned out the switch checked good however i had to replace the 4wd ecu. i also did the ADD solder mod for good measure
good posts on the wiring for the ecu and the switches

http://www.fjcruiserforums.com/foru...d-4low-xfer-case-switch-non-op-diff-lock.html

http://www.fjcruiserforums.com/foru...499-4wd-inop-constant-flashing-4wd-light.html.

i can not stress the importance of using the 4wd monthly to keep everything running right.

if you run into problems/questions, pm me.
 
#19 · (Edited)
If you were hearing clicking noises, I'll second what winterpeg said about you actually being in 4lo. Did you put your vehicle in neutral before switching from 4hi to 4lo? How fast could you go? If you were in 4 lo, top speed is maybe 25ish mph


Also, you want to be moving slowly. If you stop and wait for it to engage, there is a good chance it never will.
 
#21 ·
Ok here is the update.

I installed the atrac switch and I'm not getting the dash light to turn on.

Second - un plugged the rear diff switches to check power. I'm getting power back there constantly even when not in 4wd. It looks like it switches off the ground. When the truck is on, it gets power. The power is cycling from 0-12v when in 4lo and the RR diff switch is on.

Any ideas?


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#24 ·
if you can get the 4wd green light to stay illuminated then the 4wd ecu and add are working properly.
there are three switches on the tcase, 4hi, neutral and 4lo. the 4lo is on the right (passenger) side. if the 4wd ecu doesnt think its in 4lo it wont engage the atrac or rear diff lock. this link shows a good pic of the location of the switch.


http://i219.photobucket.com/albums/cc306/suthrnstealthrt/FJ Case install/fjcasesensor.jpg

see my previous post for tools required.

thats the only thing i can think of that the atrac and rear diff have in common.
 
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#25 ·
@FFL1 you were right. I got to the front left (drivers side) t case switch. I bypassed it with some spare wire, boom, a trac works, rear locker locked almost immediately (had a little grassy area right by me). I'll be ordering a replacement switch tonight. I didn't see how I would be able to easily get to the switch to replace it from the cabin. I'll use your previous post to get that changed. Went ahead and changed all my fluids while I was down there today minus rr diff since I hadn't narrowed down the problem yet. My gamble paid off! Thanks to everyone for all the input and help.

Once the switch gets replaced I'll post to confirm the problem is fixed.


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#26 · (Edited)
i guess i should have asked if you had a manual or an automatic.

you have to do it from underneath. it cannot be accessed by removing the center console. pull like a SOB and it will break loose.

good job on the troubleshooting.
 
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