Cdl stuck on in lowbox

Joined
Jan 5, 2021
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7
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Hokitika
Got an issue with my 91 80 series and it's center diff lock, whenever I put it into lowbox the cdl automatically comes on and I can't seem to be able to turn it off. It comes off when I go back into high but when I'm in low it just stays on. Don't know much about these as I'm quite new to the 4wd world so any help is greatly appreciated.
 

zonker

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Mar 3, 2015
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Lonely Nevada
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Read the 80 series FAQ by Romer at the head of 80 series tech forum. Lots of info to bring you up to speed in a lot of areas. Especially the CDL switch and Pin 7 modification which will help improve your current conundrum.
 
Joined
Oct 22, 2019
Messages
56
Location
San Diego
As others have said… this is standard operating procedure. Cdl switches on with low range gearing. You typically want both about 90% of the time anyways.

That being said it is so nice for the other 10% of the time when you don’t want the two things working at the same time. That’s why so many do the cdl switch and pin 7 mod. There is wiring already in place for a separate center dif button, it’s behind your center control buttons up by the rear windshield heater button. Just buy a switch, get access, plug it in, and that’s done. I believe this allows you to press cdl in 4H. Then you go to the panel behind the dead pedal, and remove the pin 7 wire. I believe that is what gives you full control of cdl on/off in any range.

I would put this on a very high priority list. It’s easy, a good project to get you started on working on the vehicle, and it’s super useful. My bro uses cdl in high range cause he can’t be bothered to switch out of 4H sometimes. I always click it off when approach a sharp and slow (yet safe) turn.

I lent my little bro the 80 one time, he had no experience and I probably isn’t coach him enough on engine braking. He rode the brakes climbing down Yosemite and lost brakes altogether. He knew enough to swap to 4L to help him get down the steep climb without running into the cars in front of him. I had swapped in the cdl switch and pin 7 mod not a week earlier. Thank for I did that little $50 upgrade saved me so much in trouble due to the binding they would have experienced.
Anyways, fun first project. Do it soon. Welcome to the club
 
Joined
Dec 8, 2006
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New Jersey
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Cheers for the info guys, that switch is definitely the next thing on the list 👍
I'm not sure about New Zealand spec, but a US spec 91 FJ80 with the fulltime 4WD transfer case has the CENTER DIFF LOCK button on the dash.
This enables you to lock/unlock the CDL in high range. There is no need to do the "pin 7 mod" on the earlier trucks as they did not have ABS and the transmission was not electronically controlled. If you simply unplug the low range switch on the top of the transfer case, the dash button now controls the CDL in both low and high range.
 
Joined
Jan 5, 2021
Messages
7
Location
Hokitika
I'm not sure about New Zealand spec, but a US spec 91 FJ80 with the fulltime 4WD transfer case has the CENTER DIFF LOCK button on the dash.
This enables you to lock/unlock the CDL in high range. There is no need to do the "pin 7 mod" on the earlier trucks as they did not have ABS and the transmission was not electronically controlled. If you simply unplug the low range switch on the top of the transfer case, the dash button now controls the CDL in both low and high range.
Ok I'll give that a shot first, thanks mate
 

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