Differential locks not working, any ideas?

[Fman]

I am selling my 1993 80 series, it has never seen a rock or piece of dirt in its 14 years of life. A potential buyer stopped by this evening and we could not get the differentials to lock.

After switching the selector to rear or rear/front, they started to blink on the dash and never stopped blinking, and the center diff. lock never came on. I waited approx. 30 seconds and nothing ever changed. The tcase was in low range. According to the manual, the diff lock should stop blinking once the axle is locked up.

Has anyone had this happen before? what were the repair steps needed to fix the problem? We have never tried these lockers up to this point, any ideas?

Thanks for the input
Fman

 

[OGBeno]

I am selling my 1993 80 series, it has never seen a rock or piece of dirt in its 14 years of life. A potential buyer stopped by this evening and we could not get the differentials to lock.

After switching the selector to rear or rear/front, they started to blink on the dash and never stopped blinking, and the center diff. lock never came on. I waited approx. 30 seconds and nothing ever changed. The tcase was in low range. According to the manual, the diff lock should stop blinking once the axle is locked up.

Has anyone had this happen before? what were the repair steps needed to fix the problem? We have never tried these lockers up to this point, any ideas?

Thanks for the input
Fman

Generally, you also need to move the vehicle a few feet for the lockers to engage with the gears inside of the differential.

Same is true for disengaging them after you are done using them.

Are you the original owner? Have you ever engaged the lockers yourself?

 

[-Spike-]

I am selling my 1993 80 series, it has never seen a rock or piece of dirt in its 14 years of life. Fman

That probably answers that question.

Try putting it in 4low multiple times, 'excercising' the center diff lock. Often they can be inoperable after not being used for long periods. Usually they can be coerced into working again. The CDL must engage before the diff locks will engage.

-Spike

 

[NorCalSam]

Generally, you also need to move the vehicle a few feet for the lockers to engage with the gears inside of the differential.

Same is true for disengaging them after you are done using them.

Are you the original owner? Have you ever engaged the lockers yourself?

ditto

 

[Fman]

That probably answers that question.

Try putting it in 4low multiple times, 'excercising' the center diff lock. Often they can be inoperable after not being used for long periods. Usually they can be coerced into working again. The CDL must engage before the diff locks will engage.

-Spike

I am assuming you are referring the CDL as the center diff. lock? If yes, the CDL is not coming on at all. We tried moving the rig forward multiple times in 4LOW but no luck with anything, just the flashing red front and rear diff. locks.

 

[cruiserdan]

The center is not locking or the signal that indicates the center is locked is your primary problem. After you get the center to lock (and indicate as such) the ends should lock if they are not gummed-up as well.


D-

 

[Fman]

The center is not locking or the signal that indicates the center is locked is your primary problem. After you get the center to lock (and indicate as such) the ends should lock if they are not gummed-up as well.


D-

I am assuming pressing in the button DIFF LOCK should activate the center diff. lock indicator on the dash? I have yet to see it come one, just the flashing frt/rear indicators. Do you know what I can do to troubleshoot the CDL switch and why it is not coming on?

My next question, typically is this a minor problem? I dont have much time to work on this rig, and dont want to stick it to the new owner if it is going to be a costly repair.

Thanks
Fman

 

[cruiserdan]

If your vehicle is stock the transfer case must first be shifted into low range to lock the center. The "difflock swith" only controls the ends.

 

[Fman]

We had it low range, then engaged the frt/rear lockers with no results other than the flashing indicators and NO diff lock light turning on.

After doing some searching on this site, I found out that it sounds like it might be the sensor on the t-case that turns on the diff lock. Does this sound correct? Someone mentioned a $50 part and easy install. Does anyone have a picture of where the sensor is located on the t-case?

Thanks !

 

[Brentbba]

So the center diff indicator is a solid 'on' or no? If like the '94 I have, if the computers don't know the center is locked it won't allow the front or rear to lock up. I hadn't used mine for the first 9 years of it's life and it took several and I mean several attempts before the center would lock up.

If the center is locking, and you can 'feel' the difference in the way the truck moves and the center diff lock indicator is not 'on' it could be a simple as the center diff lock switch on the transfer case. You can try the paper clip test. Put the truck in 4L, then while parked, pull the wiring harness from the center diff indicator on the tcase. Put a paper clip between the two sides of the harness and see if the center diff indicator goes solid 'on'. If it does the switch is bad. Around $40-45 for a smart shoppper IIRC.

 

[Fman]

The transfer case is definitely engaging in LOW range, I have no doubt about this. The lockers are not engaging, it feels no different when turning sharply on the street. I have ARBs in my 70 FJ40 and can definitely tell when the rear is locked.

When I turn the ingnition on before starting, the center diff lock light does NOT come on, the other two front and rear diff lock lights DO come on. I guess I am a little confused on how the "diff lock" light will allow the front or rear to engage. So if the light is not coming on when I turn the ignition on, does this indicate the sensor is probably bad or I have a burned out light on the dash?

 

[Fman]

Just got done doing the paperclip test, and the center diff lock light came on as soon as the paperclip was installed into the connector. I even left it in, ran it and engaged the lockers and wala, LOCKED!

I took out the old sensor, cleaned it and put it back in and it is still not working. It looks like the pin mechanism works good, kinda hard to believe it is not making good contact. If I stand correct, I believe when the tcase is engaged to LOW it activates that pin and makes contact so the center diff lock light will come on, correct?

Does anyone have the part number handy for that sensor? and a good supplier? and thanks again for all the help, I do appreciate it.

Fman

 

[cruiserdan]

You have only determied that the circuit is live. You have yet to determine if the center is really locking. It doesn't matter how many switches you replace if the center is not actually locking.


Have you tested the switch to see if the contacts close? Have you tested the vehicle to see if the center is actually locked?

 

[FirstToy]

I had a sensor not indicate a locked rear but keep blinking (it would, in fact lock).

I read on George Scolaro's site about pulling out and cleaning the CDL sensor. He also gave it a strategic hit w/ a hammer!

The rear diff sensor looked the same and so I followed George's instrucitons- and whamo, my lockers all work like butter.

 

[Brentbba]

So in your post #11 you state that by the seat of your pants, the truck is in low range. Sounds like a sensor to me. Cruiserdan is your absolute best source for that part. If the truck electronics don't know the center is locked, it won't allow the rear or front to lock. Give Dan a call - American Toyota, board sponsor x8. He's your best friend when it comes to Yota parts.

 

[Tools R Us]

Is the actuator motor running? The best way to tell is get under the truck and have a helper turn the key on without starting the motor, then shift the transfer/push the switch. You should hear the motor on top of the transfer run and shift the locker.

https://forum.ih8mud.com/showthread.php?t=68015

 

[kennyv0826]

I had a similar problem with my 94 when I bought it. It actually took driving it around in low range for a while before it tripped the CDL light to turn on (even though it felt like it was locked). Once that happend my front and rear lockers worked fine although they could prolly stand to have the motors pulled and cleaned up with new lube.

 

[Cube Dweller]

I was the driver last night. When I was trying to get the dif locks to engage I tried making a slight turn on the pavement and it felt like the drivetrain was winding indicating the center dif was locked, but I can't be sure. Also, the ABS light never came on, but was functional when I tested the warning lights w/ the ignition on position.

BTW, this is a very clean rig- no body damage that I could find, paint is very nice, interior is in good shape as well with the typical 80 leather weathering, no splits that I saw. Drove well too.

 

[cruiserdan]

If the drivetrain is winding then it's probably the indicator switch.

 

[kennyv0826]

If the drivetrain is winding then it's probably the indicator switch.

Mine didn't start working until I hit an obstacle I was trying to climb at about 15-20mph. It was almost like it jarred it enough to knock it where it needed to be.

I haven't had problems since (other than the light staying on a little longer than it should sometimes). I am going to go through both acuators when I rebuild the front and rear axles.