100 Series Central Locking Diff

[Richie]

Hi Guys, I have a 98 100 series diesel auto. After pressing the central diff lock button yesterday on the dash it will now not disengage. The button is off but the light is staying on with the lock engaged. I have tried going forwards and backwards, I have taken all four wheels off the floor and it will still not release. When pressing the button I can here no noise at all apart from the button click, no relay noise. Should I be able to hear a relay? Any other ideas?
I have to drive it so it is obviously not good for it!!!
many thanks in advance
Rich

 

[Ross IV]

Richie,
the first thing i would try is making sure you are not still in 4L.
i am not a jerk, just one thing at a time.
next shift it back and forth b/w Hi and Lo and then after that press the button until it breaks b/c of frustration. HA!

do the simplest thing first and then go tothe most complicated last. your diff will lock automatically in 4L so that could be your problem.

 

[Richie]

Hi, Thanks for the reply. It was never in 4L always 4H, It engaged with the button but never un-engaged. I can not hear any noise when the button is pushed i.e. relay or under the car.
cheers Rich

 

[100 TD]

There was another post on this I think recently, where a small part in the centre diff lock actuator broke and possibly had the same symptons. Do a search and see what you can find.

On another note
Check the 20A DIFF fuses for the CDL, probably right kick panel
Park the car on a flat surface, grass or dirt if possible (a big flat dirt area off the side of the road somewhere if possible)
Ensure IGNITION in ON
Ensure Rear diff lock is not turned OFF
Select NEUTRAL, with handbrake off
Ensure the Neutral light on your dash is lit up
Ensure the CDL switch is OUT (there is little difference between IN and OUT, push it to make sure)
Use the LOW RANGE LEVER to select NEUTRAL
PUSH the LOW RANGE LEVER "quick and hard" to select LOW RANGE
Push the LOW RANGE LEVER quick and hard from LOW RANGE to HIGH RANGE
Start engine, place transmission in drive, drive left then right while on dirt if possible.
See if anything happens.
Some of the reasons the CDL will stay locked is, something is electrically U/S, there is mechanical problems with actuator, the Low range detection switch is stuck, which over rides the push button switch and tells it to stay locked.

 

[100 TD]

If what I said to try doesn't work, then you may want to remove the actuator as in here https://forum.ih8mud.com/showthread.php?t=93242

 

[Richie]

Bugger

Thanks very much for the replies,
I have tried all of the above i.e. forwards/backwards/turning/L to H to no avail!! When I press the switch the actuator is doing nothing, no noise at all, and there is no noise from a relay, I presume that there must be a relay in the circuit somewhere?? Does anyone know which relay is associated with it?? Is it the black one with transmission written on the side?? I think this is an electrical problem but I can see myself having to take the actuator off tomorrow if I can't get to the bottom of it so it can unlock itself!!!
cheers Rich

 

[100 TD]

PM me your email address and I will send you a 2000 CDL circuit diagram, I doubt there is any difference in it compared to yours

 

[100 TD]

If the low range detection switch is stuck, you wont actuate any relay or motor as this inhibits the control of the switch.

 

[100 TD]

From your PM it sounds like a broken actuator or fuse/electrical problem but you have to send me your email address to get the diagram you requesred!

 

[hoser]

You can check the CDL actuator for engagement/disengagement. Crawl underneath to the transfer case and locate the plug. The CDL is towards the front and on top of the transfer case and the wiring and connector run down the passenger side (your DS). Use a little 9 volt battery or 12v source. If you can't hear it engage/disengage, you'll have to drop the transfer case slightly and remove the CDL.

There is also a CDL sensor towards the back of the transfer case on the same side. This simple push ball sensor tells whether your CDL is engaged or not. If stuck in the closed position, your CDL light will never go out. Can easily removed and tested.

This is all from the memory of my 80 series but I believe it still applies.

 

[Richie]

Update

Update:
Ok, After going through the circuit diagrams and testing various bits it seems that there should be two permanent lives to the motor and two switching earths. My two lives are not present!! When I put it into L or push the button in one of the switching earths is trying to work but with no lives present at the motor, it is doing nothing. The permanent live into the relay is there but it is not producing the two lives to the motor..... Does this point to a knackered relay???
I hope not because at $356 for a relay it could be expensive!!!! Does anyone know how to test the relay to see if it is working properly?
And lastly!, would it do any damage if I connected a live directly from the battery to the two on the motor so that I can try and disengage the diff lock??
Many thanks, hope this makes some sense!!!
Rich

 

[100 TD]

No damage will occur (famous last words!), PM me your phone number and I will give you a call and talk with you about what you have and have not.

 

[Richie]

Diff Lock disengaged!!

Thanks for all the replies, I bypassed the relay and the lock disengaged straight away!! I either have a dodgy relay or a dodgy switch!! Either way it is back in normal drive mode which is good!!
cheers Rich

 

[100 TD]

Good to hear, I ran out of time to ring you last night, let me know if you want me to call.