FJ80 DIFF LOCK ISSUES

[dak4]

I have a 1993 fj80.
My rig is parked on a hard surface, and when I start the truck, the Diff Lock engages and the ABS light also lights up on the dash. I can feel the Diff Lock is on, and it won't disengage. I have tried, putting it in reverse and backing up a little bit and driving forward. It doesn't disengage.
Any Help is appreciated.

 

[bulhas]

are you new to the rig?? is their a CDL switch activated?? perhaps the transfer case shift knob is pushed forward

I tend to drive in an S pattern when things wont unlock or lock....

 

[dak4]

are you new to the rig?? is their a CDL switch activated?? perhaps the transfer case shift knob is pushed forward

I tend to drive in an S pattern when things wont unlock or lock....

Thanks for the reply.

I am new to this one. I had a 91 for years, but it was slightly different as far as the diff lock goes. This year does not have a CDL switch. There is a spot for it if I want to install one. The transfer case shift knob is in the HIGH position now.

I was thinking of taking it for a spin, but I heard driving with DIFF Lock on Hard surfaces can damage the drive train.

 

[Grim Reaper]

If it's in high and UN modified the diff lock should not engage. As wired from the factory you only get the diffs locked in low. Is the diff light(s) blinking? It's not locked till it's a solid light.

If you turn the diff knob on in high it will blink but not engage.

For driving on the street turn the diff knob counter clockwise till it stops. That should turn off the lights on the dash. And yes you don't want to drive on pavement with the diffs locked. It will drive horrible and you can break axle shafts and other expensive things.

 

[yohavos]

A quick (somewhat reliable?) way to see if someone has previously installed a CDL switch is to pop open a switch blank or the dash to see if the terminator is still on the factory CDL switch wiring.

If the terminator is gone, someone probaly had a CDL switch installed then yanked it. I'm not sure what would happen if the terminator wasn't there.

Another option is to check your 4L position sensor on the t-case. If it's failed (or stuck?), it may act like the truck is in low and will keep your center diff locked.

Any more info on the back story here? Were you driving it in LOW before this?

 

[dak4]

A quick (somewhat reliable?) way to see if someone has previously installed a CDL switch is to pop open a switch blank or the dash to see if the terminator is still on the factory CDL switch wiring.

If the terminator is gone, someone probaly had a CDL switch installed then yanked it. I'm not sure what would happen if the terminator wasn't there.

Another option is to check your 4L position sensor on the t-case. If it's failed (or stuck?), it may act like the truck is in low and will keep your center diff locked.

Any more info on the back story here? Were you driving it in LOW before this?

Thanks for the Reply. I will check the terminator for the CDL. As for the 4L position sensor, how can I check that? When putting it into 4Low it is hard to get it there. Very stiff. But it gets there, and into Neutral and back to 4 High same thing. very stiff. About a week ago I drove it in about a foot of snow in the mountains in 4 Low. The CDL automatically kicked in like it should and turned off once I put it back into 4 High.
I noticed the problem the other morning. The day before I had put the 4 Low on, but didn't drive. I put it back into 4 high and shut the engine off. It was on a hard surface. The next day I noticed the diff lock was on and ABS off in 4 high. Not sure if that has anything to do with it, or just a coincidence.

 

[dak4]

If it's in high and UN modified the diff lock should not engage. As wired from the factory you only get the diffs locked in low. Is the diff light(s) blinking? It's not locked till it's a solid light.

If you turn the diff knob on in high it will blink but not engage.

For driving on the street turn the diff knob counter clockwise till it stops. That should turn off the lights on the dash. And yes you don't want to drive on pavement with the diffs locked. It will drive horrible and you can break axle shafts and other expensive things.

Thanks for the reply.

There is a solid light and the ABS light is illuminated. There is no diff Knob on mine.

 

[yohavos]

I noticed the problem the other morning. The day before I had put the 4 Low on, but didn't drive. I put it back into 4 high and shut the engine off. It was on a hard surface. The next day I noticed the diff lock was on and ABS off in 4 high. Not sure if that has anything to do with it, or just a coincidence.

Okay -- this may not be too much of a problem. If I understand correctly, you put the truck in 4LO, which locked the center diff. Then, you put it back in 4HI, without moving, and turned it off.

If the center diff didn't unlock after you put it back in 4HI, then a little movement should let it do so. Turning on pavement with the CDL is the issue, straight lines aren't as bad (though it's not good practice to be on pavement with CDL locked period).

If it's possible, moving the rig a bit (in straight line if you can help it) may be enough to let the CDL disengage. Getting it to a non-paved or slick surface would be ideal...

 

[ppc]

Pull the connector off the passenger side of the rear extension on the transfer case. That is the 4Low sensor. If that sensor switch is stuck in a shorted position the CDL will not unlock. If disconnecting the connector turns the CDL and ABS lights off you know the cause being the sensor switch. This is for a non-modified setup.

 

[CJF]

Driving it locked on the pavement won't hurt a d*mn thing.

Go take it for a spin already.

Welcome,

Curtis

 

[dak4]

I went for a short drive and got the diff lock to disengage. I went over to a rocky/dirt field to see if I could get to diff lock back on in 4 Low, and it wouldn't go on, and the ABS light did not come on either. Some kind of relay or sensor issue?

 

[Pin_Head]

If the CDL and ABs lights don't come on, then the F&R diff lockers won't work. Either the center diff isn't locking or the sensor isn't indicating that it is locked.

 

[CJF]

I went for a short drive and got the diff lock to disengage. I went over to a rocky/dirt field to see if I could get to diff lock back on in 4 Low, and it wouldn't go on, and the ABS light did not come on either. Some kind of relay or sensor issue?

Most likely just sticky from lack of use.

Put in Lo, drive up and down your street till it locks, put in Hi, drive up and down till it unlocks, repeat.

 

[ikeedikeed]

^^^THIS.
It could be that you're expecting instantaneous locking, when it usually requires 1-5 seconds of driving to engage or disengage ANY locker, centre, rear or front. If it's being stubborn, drive in increasingly large Ss until it works. You can't just sit there motionless expecting it to work instantly.

 

[CruiseOrlando]

You can also just jack up the rear end so the tires come off the ground. They should unbind and allow it to unlock if there's some kind of mechanical issue keeping the locker engaged.

 

[Benbmore3d]

Anyone know why an ABS and Diff Lock light would come on when my 1995 fzj80 does NOT have diff locks? I was in 4 wheel low and they came on. Nothing felt wrong and 8t performed fine but those lights came on. The lights went 9ff once I was back in regular High, Drive. Any ideas? Thanks in advance.

 

[Pin_Head]

Because you have a locking center differential?

 

[subzali]

Anyone know why an ABS and Diff Lock light would come on when my 1995 fzj80 does NOT have diff locks? I was in 4 wheel low and they came on. Nothing felt wrong and 8t performed fine but those lights came on. The lights went 9ff once I was back in regular High, Drive. Any ideas? Thanks in advance.

That is normal factory operation. Your 1995 has a CENTER diff lock that is automatically locked when you shift into low range.

 

[Fj80oregon]

Because you have a locking center differential?

 

[Fj80oregon]

That is normal factory operation. Your 1995 has a CENTER diff lock that is automatically locked when you shift into low range.

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