Center Diff light on, no center diff lock. (1 Viewer)

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Joined
Feb 7, 2023
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Coos Bay, OR
Hey guys, I just bought my first land cruiser I named "The Land Crusher" off of my fathers fj40. Anyways, I bought my fj80 with the 3f for $4,000. Said the diff lock was stuck on, but I drove it and realized it wasn't on. But the light is on and it wont engage. I have a switch next to my defroster switch that doesn't work and it doesn't engage in L. Any ideas on how to troubleshoot? Thank you.
 
How do you 'know''the CDL isnt physically engaged?
 
How do you 'know''the CDL isnt physically engaged?
As far as I know, when you turn hard when you have it engaged, the far side wheel (turning left, the right wheel, or vise versa) will jump. I can also run highway speeds perfectly fine and at 16mpg. I assume that means its disengaged but im not sure.
 
Does it have freewheeling hubs on the front? It may have had a part-time kit installed and is giving a false engaged signal.

To test for CDL engagement properly you really need to disconnect the front propshaft (there are other more risky methods.....) and see if the transfer case still provides drive to the rear shaft.

Another possibility is that the CDL solenoid is actually engaged, but the CDL is busted.

Check all the plugs are connected to the transfer case. From memory there are two related to the CDL. One for CDL engage/disengage via the dash switch, and another forces CDL engagement when low range is selected regardless of dash switch selection (though US market & auto transmission models might differ).
 
Does it have freewheeling hubs on the front? It may have had a part-time kit installed and is giving a false engaged signal.

To test for CDL engagement properly you really need to disconnect the front propshaft (there are other more risky methods.....) and see if the transfer case still provides drive to the rear shaft.

Another possibility is that the CDL solenoid is actually engaged, but the CDL is busted.

Check all the plugs are connected to the transfer case. From memory there are two related to the CDL. One for CDL engage/disengage via the dash switch, and another forces CDL engagement when low range is selected regardless of dash switch selection (though US market & auto transmission models might differ).
Im not too familiar with anything 4x4 yet, trying to learn. If its related at all, what are freewheeling hubs? I will check the wires tomorrow though. Thank you.
 
80 series is a great vehicle to learn on :)

Here is a great resource explaining how differentials work in practice, and differentiates (ha ha, see what I did there :rofl: ) between centre diffs (CDL) and front/rear diffs.

And, this may assist with troubleshooting and component location: Land Cruiser 80 Series (HDJ80) centre diff lock troubleshooting - Motor-Roam - https://motor-roam.co.uk/land-cruiser-80-series-hdj80-centre-diff-lock-troubleshooting Or here for much more detail: Troubleshooting the Toyota FJ80 Land Cruiser Center Diff Lock (CDL) - - https://www.pnwadventures.com/toyota-fj80-landcruiser-cdl-troubleshooting/


I think it's highly unlikely your vehicle has a part-time kit installed, but freewheeling hubs (FWH) are components which lock/unlock the outer ends of the front axles from the wheel hubs. They may be manually or electrically switched/actuated.
Manual types look somethig like this:
1676165671901.jpeg
 
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The light on the dash is activated by the switch on the front of the transfer case, same type switch as what activates reverse lights in a manual gearbox.
If the switch is faulty it could be jammed internally in the on position or its plunger stuck causing the light to be constantly illuminated.
Jack one wheel off the ground, put trans in neutral / handbrake off and try turning the prop shaft that the raised wheel is driven by. If you can turn it then its not locked (look at the switch then), if you cant turn the prop shaft then probably locked up however would have imagined some bad trans windup would have damaged something by now
 
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Hey guys, I just bought my first land cruiser I named "The Land Crusher" off of my fathers fj40. Anyways, I bought my fj80 with the 3f for $4,000. Said the diff lock was stuck on, but I drove it and realized it wasn't on. But the light is on and it wont engage. I have a switch next to my defroster switch that doesn't work and it doesn't engage in L. Any ideas on how to troubleshoot? Thank you.
Start by removing the sensor switches on the TC. Check them one at a time for continuity and replace if necessary. That's the easiest, least expensive check that may solve the issue. There is a transfer indicator switch, a neutral position switch, and 1 other (name escapes me). At least those are what are on my FZJ80 which 2 were bad and needed replacement.
 

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