Rear Differential Lock Won’t Engage (1 Viewer)

Joined
Feb 9, 2005
Messages
24
98 LC, 60 K miles. Just got around to testing factory Rear Differential Locker. Icon comes on but then starts blinking. I tried forward and reverse driving (very slow speed) in Low Range on dirt, also turning---no joy. All other indicators seem good: Center Differential and ABS icons come on as they should. I suspect lock in not engaging since I can make short turns without dragging a rear wheel.

The FSM is not much help, nothing in the Diagnostics Volume, and the Repair Volume starts out with “jack up all four wheels and start engine”; I’m not equipped to do that. I did check the fuse and it’s OK.

Am I overlooking something simple, something else to make it kick in? It’s no big deal since I probably will never have to lock the differential, but it’s on the vehicle so I would like it to work.

No way to contact the PO, but I suspect this feature was never used since it came of the production line.

Thanks for any advice you can give me.
 
Joined
May 29, 2005
Messages
150
Location
Connecticut
 
I haven't locked mine since last winter, but I recall the blinking but then it "kicked-in" and the blinking stopped and the rear lock indicator on the dash stayed on. I will try mine again right now. Stay tuned.
 
Joined
May 29, 2005
Messages
150
Location
Connecticut
 
Just tried it again and the rear diff indicator come on right away and did not blink. I started by putting it into "L" and then locked the center diff, then locked the rear. Everything appears to be working, center diff, rear diff, and ABS lights were on.. no blinking.
 
Joined
Nov 15, 2003
Messages
637
 
 
 
Desert Rat,

It can be a number of things; it could be the locker itself or a relay somewhere.

I had a similar situation with my 99 LC. I checked the obvious stuff (for me). I swapped relays with a friend that has another 100 series, I checked fuses, I went underneath the truck and had someone turn the lockers on so I can hear if it is engaging or not.

It turned out that is was a small solenoid on the transfer case itself. This little solenoid will tell the ECU that the transfer case is actually in low range, and then it will lock the rear lockers. It was a $80 something part from the dealer.

Anyway, I hope you figure it out. I had to take mine to the dealer to figure it out. Good luck.
 

tabraha

Hello My Name is: TAD
SILVER Star
Joined
Aug 20, 2003
Messages
2,546
Location
South Carolina
 
 
 
Repeatedly try to activate the locker too. If not used every once in a while it can freeze slightly. Attempting to engage several times in a row can sometimes gradually get it back free again so that it can engage.
 
Joined
Mar 3, 2004
Messages
2,080
Location
OZ
 
Below is a list of things to make it flash.
I expect the most probable cause to be not locking fully due to no use. If this is the case then repeated on off cycles while driving on dirt in low range may just get it unsiezed. The detection switch in the diff will only operate when it is fully locked, so it may not be activated if the lock is a bit siezed.
However if the "low" range detection switch on the transfer is not activated, it will cause the light to blink and not lock. Try reselecting low range aggressively, to get the low range switch to work.


From the 1999 diff lock circuit info

The rear diff. indicator light blinks under the following conditions :
* When the rear diff. lock SW is turned on with the ignition SW on and the transfer lever at a position other than L.
* When the rear diff. lock SW is turned on at a speed over 8 km/h (5 mph), with the ignition SW on and the transfer position
lever at L position.
* When the rear diff. lock motor is operating the rear differential to free from lock, and the detection SW (Rear diff. lock ) is
off.
 
Joined
Feb 9, 2005
Messages
24
Thanks everybody.

I'll keep trying to engage the lock and see if it frees up. Either it's 'sticky' or the motor or ECU is faulty. If I can't get to work right, someday I may troubleshoot further.
 

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