Need live help: '92 diff-lock light on and locked, didn't push button

[GCRad1]

I'm on the road and my diff-lock light came on and it is indeed engaged and I did not push the button. I am in at Cisco grove campground an hour away from Reno or Sacramento on HWY80.

I am starting with unhooking the batter to see it that works. I will check fuses next.

Any other suggestion as I do not want to drive all the way back to SoCal locked!

Thanks in advance Mud members!

 

[Cruiser804]

Center diff or one of the axles?

 

[SUMMIT CRUISERS]

If you can't get the CDL light to come off and to unlock, you could remove the front drive shaft and drive home in rear wheel drive. Two 14mm wrenches will do the trick. I would try about everything from driving in reverse while pushing the button to try to get it to unlock. Not sure if anything bad would happen while running it on the pavement with the cdl locked, the only time I did it (by mistake) the front end lurched a bit while tight turning. Could be bad on the birfields. Maybe someone else can chime in.

 

[bryson]

Don't push the button again - see if that works.

Sorry... I had to.

If you do have to drive with the CDL locked, the advice to take off the front driveshaft is good advice. As long as the CDL stays locked, it won't cause you any problems. Good luck!

 

[LINUS]

Doesn't the emergency flasher light switch plug in & work like a CDL switch? you could swap, then unlock & then just either leave the e-flasher switch plugged in, or pull it & leave the wiring pigtail alone, in case the CDL switch is shot & tried to lock it again.

 

[jonheld]

Shifting the transfer case into low range will lock the center diff. Try shifting back and forth between low and high range and see if that helps.

There is a plug on the rear of the transfer case (1:00 when looking at the rear of the case) that runs the CDL in low range. Remove that plug and see if you now have control from the dash switch.

Exercise the dash switch several times.

If nothing works then it's possible that there is a short somewhere in the wiring either from the dash switch or the transmission harness that runs under the truck.

If you're on the road, I'd simply leave it locked and remove the front drive shaft. It won't hurt anything but the truck will handle differently.

 

[matttaylor1976]

If you're still having issues, i'll be up at Eagle Lakes in about 4 or 5 hours. I could swing by and give you a hand. PM on its way.

 

[JohnVee]

Have you tried unhooking and rehooking the connector for the diff lock switch on the transfer case? It's a plug connector on the top front passenger side of the TC. You can also remove the switch itself (the sensor looking thing the harness connects to) and exercise the switch manually. There will be a spring loaded ball at the end of the switch. You can cycle that by hand and maybe clear any fouling inside it. 17mm wrench needed, maybe? Or an adjustable will get you there, too. Maybe just unhooking the connector will defeat the CDL.

Let us know how it goes. Good luck.

--john

 

[Satchmo]

Hey sorry if I'm too late :

I've had the same problem before, and the lock disengaged if I just started driving once I reached about 30 mph. (with the CDL switch off, of course) Just make sure to drive really slow until you have a straight line to pick up speed on. Good luck! I hope you're already out of there

 

[itbrokeagain]

My cdl is also stuck on and has been for over a year. I have 60 hubs up front so its not a big deal. Imo its easier to take the drive flanges off

 

[GCRad1]

Ok, thank you all for all the advise! While I was prepared to just remove the front drive shaft, I didn't. I first removed the 20amp fuse for the CDL that is located in the fuse panel below the steering wheel. After removing that, it don't seem to have any effect as the CDL was out for a moment when I restarted and the light came back on. We noticed that when we taped on the solenoid body on top of the transfer case we could hear it trying to do something. But we also could hear noise from the side kick panel. User there is a black box with "transmission" on it, so we unplugged it. CDL light is now off. I drove it around in the campground and no binding in the front end. So for now, I am going to drive it home. If I have an issue on the transit home, I will simply pull the front drive shaft. I'm quite alright with that as I drove 9-months with it in 2WD with CDL locked when I broke the outter front stub axle housing. I have all that shown in my build thread.

Again, thanks for all the help and I will see how it goes from here!

 

[landcrshr]

Of course, you could always try pulling the pin #7 wire from the CDL control relay. (pin 7 mod)

 

[jonheld]

Of course, you could always try pulling the pin #7 wire from the CDL control relay. (pin 7 mod)

Pin 7 mod not applicable to FJ80s.
Actually, it is applicable, but it is the same thing as pulling the connector on the transfer case. Since the shift points on an A440F are not electronically controlled, it does nothing else.

 

[jonheld]

GCRad1,
The CDL actuator powers in both directions for lock/unlock. It is not spring loaded where it auto returns to an unlocked position.
It is possible that the end position fingers on inside of the actuator assembly are toast. These trigger the logic for lock and unlock final position.
That would explain why the motor is trying to constantly lock or unlock, but that needs to be bench tested to confirm.

Once you get off the road and settled back at home and can diagnose the system, post up again.

 

[landcrshr]

Pin 7 mod not applicable to FJ80s.
Actually, it is applicable, but it is the same thing as pulling the connector on the transfer case. Since the shift points on an A440F are not electronically controlled, it does nothing else.

Right, but if it were a wiring issue between the 4LO switch and the control relay then pulling pin 7 would remove the false 4LO condition, where as pulling the connector from the switch would do nothing.

 

[jonheld]

True. It would be a logical way to troubleshoot the harness.