1992 fj80 noise when center diff lock is off

[pnw92]

Crazy to issue last night. Driving on the 2 lane hwy in the snow my 1992 pc lost all power, headlights, everything just turned off and black. Used the jumper box x and got it fire back up. Super scary without even hazard lights. Happened 2x more times. Had someone come out and bring a battery. Limped it home and when I pulled off the hwy the lc died again. When I tried to jump it no love. Son walked a mile home and grabbed another battery. Started up but when I put it in R, or Drive it made these horrible grinding sounds from the front end and wouldn’t drive. As a last resort I pushed the Center Diff Lock and was able to make it the mile home. See video below. Any suggestions? We live in the mountains and this is our only transportation. Thank you

New video · Saturday, Dec 27 🎬

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[ppc]

Crazy to issue last night. Driving on the 2 lane hwy in the snow my 1992 pc lost all power, headlights, everything just turned off and black. Used the jumper box x and got it fire back up. Super scary without even hazard lights. Happened 2x more times. Had someone come out and bring a battery. Limped it home and when I pulled off the hwy the lc died again. When I tried to jump it no love. Son walked a mile home and grabbed another battery. Started up but when I put it in R, or Drive it made these horrible grinding sounds from the front end and wouldn’t drive. As a last resort I pushed the Center Diff Lock and was able to make it the mile home. See video below. Any suggestions? We live in the mountains and this is our only transportation. Thank you

Have you checked to make sure the transfer case is not in neutral?
Otherwise a stripped front drive flange, broken birfield or axle. When there is one wheel spins all the torque goes to that one wheel. When the CDL is locked 50 percent of the torque is sent to the rear axle. Because the center is locked then both drive shafts rotate at the same speed. In your case the noise while shifting to park is the parking pawl is ratcheting because the transmission , transfer case front driveshaft is still rotating while the vehicle is stopped.

 

[pnw92]

My son and I are going to crawl under and look at the transfer case. I ran what you responded with into Gemini and it spat this out. Is this what we should be looking for?

A 1992 FJ80 Land Cruiser being stuck in "Neutral" on the transfer case (meaning the engine revs in gear but the wheels don't move) is typically caused by a failure in the mechanical linkage or a vacuum/electrical issue if you have a center differential lock involved.


Since the 1992 FJ80 features a constant 4WD (Full-Time 4WD) system, the transfer case shifter only controls the High/Neutral/Low ranges, while a dash button or automatic logic controls the Center Diff Lock.


1. Physical Linkage Failure (Most Common)


If the shifter feels "loose," "floppy," or has no resistance, the linkage has likely disconnected or a bushing has perished.


• The Pivot Bolt: There is a pivot bolt on the side of the transfer case where the linkage connects. These are notorious for backing out or seizing.


• Plastic Bushings: Small plastic bushings at the linkage ends can dry rot and fall out, causing the rod to slip out of the eyelet.


• Diagnosis: Crawl under the vehicle (driver’s side) and have someone gently move the transfer case lever. Look for a rod that is moving but not actually pushing the lever on the side of the transfer case.


2. Shift Rail "Jam"


The FJ80 transfer case (HF2A) requires you to push the lever down/forward or left/right (depending on the specific gate) to move from High to Low.


• The "Seized Shifter" Syndrome: If the transfer case isn't used often, the external shift pivot on top of the case can seize due to road salt and grime.


• Internal Fork Misalignment: If the vehicle was shifted forcefully while under "gear bind" (driveline tension), the internal shift fork can occasionally get stuck between gates.


• Diagnosis: If the lever is rock solid and won't budge into High or Low, the external pivot is likely seized. Spray it heavily with PB Blaster or Kroil and let it sit.


3. Driveline Bind


If you were in 4-Low or had the Center Diff Locked on a high-traction surface (pavement), the gears may be "bound" so tightly that the spring-loaded internals cannot pull the collar back into gear.


• Diagnosis: Try to "rock" the vehicle. With the engine off and the transmission in Neutral, have a couple of people physically rock the Land Cruiser forward and backward while you try to move the transfer case lever. This often relieves the pressure on the gears.


4. Center Diff Lock Confusion


In a 1992 FJ80, the transfer case Neutral is a true mechanical disconnect. However, if your Center Diff Lock (CDL) is engaged but one of your driveshafts or axles is broken, the truck will not move (power escapes through the broken side) until the CDL is active.


• Diagnosis: Check if your "Center Diff Lock" light is on. If the truck moves only when the button is pushed but stays "dead" when it's off, you have a broken axle or CV joint, not a transfer case issue.


Recommended Quick Fixes


1. The "Two-Person" Rock: Shift the main transmission to Neutral, turn off the engine, and rock the truck vigorously while pulling the transfer case lever toward "H" (High).


2. Visual Inspection: Slide under the middle of the truck with a flashlight. Look at the driver's side of the transfer case. Check if the linkage rod (about 1/4" thick) is actually attached to the lever on the case.


3. Check the "CDL" Button: Ensure the Center Diff Lock isn't stuck in a "half-way" state which can sometimes confuse the vacuum/electric actuators.


Would you like me to find the specific part numbers for the linkage bushings or a diagram of the shift linkage assembly?

 

[ppc]

@pnw92 ,

Ignore all that Gemini AI bullsh1t. The center differential is working as it should.

Use the forum search or Google this website for "stripped drive flanges".

 

[Kernal]

Ditto what PPC said: have your son stand (safely) outside the vehicle while you put the transmission into gear.
Have him try to pin-point the source of the sound including near the front drive flanges (under the plastic wheel covers if they're still in place)
Do not get under or directly in front or behind the vehicle of course while doing this.

Agree also, it's generally a more efficient use of your time to just come to this forum, try some searches on your own, then ask your questions.

 

[jonheld]

1992 pc lost all power, headlights, everything just turned off and black. Used the jumper box x and got it fire back up. Super scary without even hazard lights. Happened 2x more times. Had someone come out and bring a battery. Limped it home and when I pulled off the hwy the lc died again. When I tried to jump it no love. Son walked a mile home and grabbed another battery.

Corroded/loose battery terminals or fusible links. I would put money on fusible links if they've never been changed in 33 years. 90982-08264. Lives off the positive battery terminal.

Started up but when I put it in R, or Drive it made these horrible grinding sounds from the front end and wouldn’t drive. As a last resort I pushed the Center Diff Lock and was able to make it the mile home.

Stripped front drive flange. More common on the older 91/92 FJ80 due to the length of the drive flange splines.
You can keep the CDL locked and continue to drive until you replace the flange.

 

[mudgudgeon]

Have you checked to make sure the transfer case is not in neutral?

When the CDL is locked 50 percent of the torque is sent to the rear axle.

Not if it's in neutral

 

[mudgudgeon]

I ran what you responded with into Gemini and it spat this out

Damn dude!
The dribble from Gemini is going to keep mechanics employed well into the AI future!


Sounds like you are dealing with two different issues.
Coincidence they both popped up together? Or both exacerbated by the conditions you were in? Probably.

@jonheld has given solid advice above.

 

[pnw92]

Corroded/loose battery terminals or fusible links. I would put money on fusible links if they've never been changed in 33 years. 90982-08264. Lives off the positive battery terminal.
View attachment 4056555

Stripped front drive flange. More common on the older 91/92 FJ80 due to the length of the drive flange splines.
You can keep the CDL locked and continue to drive until you replace the flange.

View attachment 4056556

 

[pnw92]

Is there any is there any restrictions on speed or concerns with handling we should watch out for? We are going to attempt to drive to the dealership if we can make it the 120 mile round trip and pick up the parts you mentioned. We both really appreciate the help. Tottally new to Land Cruisers. We have only had ours for 7 months.

 

[mudgudgeon]

Is there any is there any restrictions on speed or concerns with handling we should watch out for? We are going to attempt to drive to the dealership if we can make it the 120 mile round trip and pick up the parts you mentioned. We both really appreciate the help. Tottally new to Land Cruisers. We have only had ours for 7 months.

I would remove the drive flanges from both front hubs. Clean the hub up the best you can, and use some duct tape to seal over the open end of the hub as neatly as you can. Aim is to keep road grime, dirt, water, salt etc out.
Ideally, remove the front driveshaft also so the front differential is not spinning. ( for a limp home scenario, leaving the driveshaft in would be ok)

With flanges removed (and hubs covered), CDL locked, driveshaft removed, you can drive indefinitely like this. Your vehicle essentially becomes a rear wheel drive vehicle. Drive it as you would any other vehicle.

 

[pnw92]

Located the sound. Passenger front. See video below. What would cause the grind sound when it is put in park? Still same?

New video · Sunday, Dec 28 🎬

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[pnw92]

Ditto what PPC said: have your son stand (safely) outside the vehicle while you put the transmission into gear.
Have him try to pin-point the source of the sound including near the front drive flanges (under the plastic wheel covers if they're still in place)
Do not get under or directly in front or behind the vehicle of course while doing this.

Agree also, it's generally a more efficient use of your time to just come to this forum, try some searches on your own, then ask your questions.

Did what you suggested see post below for what we found.

 

[pnw92]

I would remove the drive flanges from both front hubs. Clean the hub up the best you can, and use some duct tape to seal over the open end of the hub as neatly as you can. Aim is to keep road grime, dirt, water, salt etc out.
Ideally, remove the front driveshaft also so the front differential is not spinning. ( for a limp home scenario, leaving the driveshaft in would be ok)

With flanges removed (and hubs covered), CDL locked, driveshaft removed, you can drive indefinitely like this. Your vehicle essentially becomes a rear wheel drive vehicle. Drive it as you would any other vehicle.

Currently removing the front drive shaft

 

[pnw92]

With the front passenger tire off the ground we noticed the front drive shaft does not rotate when the tire is rotated. Is this still pointing to the flange being the issue?

 

[mudgudgeon]

Pop this cap off, you'll need a hammer and a large flat screwdriver to pry ot free from the hub.
If you already have the driveshaft out, have your helper turn the diff pinion flange by hand, you'll see the birfield/CV axle shaft spinning inside the flange behind the first cap.
The flange and axle shaft should be locked together with splines.
The splines wear out. When they are worn too much, eventually, there's nothing left to connect the inner axle shaft and the hub. Therefore no drive.

 

[pnw92]

Pop this cap off, you'll need a hammer and a large flat screwdriver to pry ot free from the hub.
If you already have the driveshaft out, have your helper turn the diff pinion flange by hand, you'll see the birfield/CV axle shaft spinning inside the flange behind the first cap.
The flange and axle shaft should be locked together with splines.
The splines wear out. When they are worn too much, eventually, there's nothing left to connect the inner axle shaft and the hub. Therefor

 

[jonheld]

With the front passenger tire off the ground we noticed the front drive shaft does not rotate when the tire is rotated. Is this still pointing to the flange being the issue?

Most likely.

 

[pnw92]

I would remove the drive flanges from both front hubs. Clean the hub up the best you can, and use some duct tape to seal over the open end of the hub as neatly as you can. Aim is to keep road grime, dirt, water, salt etc out.
Ideally, remove the front driveshaft also so the front differential is not spinning. ( for a limp home scenario, leaving the driveshaft in would be ok)

With flanges removed (and hubs covered), CDL locked, driveshaft removed, you can drive indefinitely like this. Your vehicle essentially becomes a rear wheel drive vehicle. Drive it as you would any other vehicle.

 

[CJF]

^^^