center diff - no engage (1 Viewer)

Joined
Mar 5, 2014
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377
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outside Atlanta
Hello all,
Just came home from work today and it had rained so I decided to cycle my diffs in the yard - just to keep them on their toes.
I have a 94 with lockers and ABS.
well the center lock didn't engage so neither would my fronts and rear. I only tried it about 10 times and gave up. Came in and did some searches and will have to check later to see if the actuator is making any noise etc. and also try to engage it about 500 more times...
The thing that bothers me is I do not get a center diff light when the key is turned on. I do get the abs and front and rear lights. When trying to engage I noticed the ABS light didn't come on either. Isn't the lights coming on when the key is turned on separate from actually engaging the lock?
Well I'm beat tonight so will check back in tomorrow.
thanks,
Jerry
 
Joined
Feb 5, 2014
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1,361
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Weilerbach, Germany
I'm probably just pointing out the obvious, but when rarely used, the actuator will likely bind-up. I think if the actuator is bound, the light won't work at all.
 

murf

Lifer
Joined
Jun 24, 2007
Messages
10,516
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Scottsdale, Arizona
Yes, check the actuator for the center diff located on top if the tcase. The axle actuators are actually the same so you an swap one of those over for a test. Once you get the center diff to lock the abs light will come on once it "sees" the center diff actuated.
 
Joined
May 17, 2003
Messages
1,191
Location
Irving, TX
It's also possible that it's engaging, but the sensor is not making contact, which will prevent the diff lock and ABS lights from coming on. Have you tried it on a higher traction surface to see if the driveline binds up?
 
Joined
Nov 26, 2013
Messages
91
Location
Melbourne Australia
Climb under and take off the plugs that go to the actuator and check/clean them (at the rear/top of the TC), mine were full of dried up mud that stopped the CDL engage.
 
Joined
Oct 25, 2011
Messages
439
Location
Alabaster, Alabama
I'm gonna bet it's the sensor that has gone bad. If you are hearing the locker actuator cycle but getting no light after you've moved the truck around in the dirt then then the sensor is bad. You're CDL is most likely locking. The sensor is just confirming it's locked. Quick test is to pull off the connector that goes to the sensor on the transfer case and jump the 2 prongs on the harness side of the connector with a paper clip or piece of wire . You should get a CDL light then.
 

allan man

SILVER Star
Joined
Mar 9, 2008
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Las Vegas,Nevada
Those sensors can be cleaned....I had this problem in the past drove me At my absolute wits end turned out to be my actuator ......I just cleaned the the copper contacts on the spur gear...... Be careful when you take it apart mark the position of the spur gear otherwise it will over/under turn your spur gear and lead you to more problems.
Drop your t case about 4" it is accessible from the top without taking it off completely.
 
Joined
Mar 5, 2014
Messages
377
Location
outside Atlanta
Thanks for all the input. At work so haven't been able to mess with it because I need to get home tonight:)
I did try a few things , tried the ctr on pavement this morning- no help, then I just turned key on and shifted to 4lo - I didn't hear the actuator or anything and no lights still.
Pulled the diagram off all data just to look it over. Looks like the L4 transfer position sw is what sends power to the relay then to the actuator. Is that switch on the transfer case or possibly under the console on the shifter? Was also wondering if your CTR diff light comes on momentarily when you turn the key on- like the FR/R diffs.
Again thanks for the help and will try to get on it as ASAP
Jerry
 
Joined
Mar 5, 2014
Messages
377
Location
outside Atlanta
I'm gonna bet it's the sensor that has gone bad. If you are hearing the locker actuator cycle but getting no light after you've moved the truck around in the dirt then then the sensor is bad. You're CDL is most likely locking. The sensor is just confirming it's locked. Quick test is to pull off the connector that goes to the sensor on the transfer case and jump the 2 prongs on the harness side of the connector with a paper clip or piece of wire . You should get a CDL light then.
I will def try this just to make sure bulb is good
Thanks
 
Joined
Jul 26, 2012
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SacTown!
I had the same problem and if not used for a while it will give you some trouble. This could be just me but when I had the issues I left it on by accident and drove it for a while. After a while all of sudden on the freeway the CDL engaged(need CDL switch mod), must be all the vibration and movements of gears. Once it worked I can cycle it freely with the switch, just need to remember to exercise it once in a while.
 
Joined
Mar 5, 2014
Messages
377
Location
outside Atlanta
I had the same problem and if not used for a while it will give you some trouble. This could be just me but when I had the issues I left it on by accident and drove it for a while. After a while all of sudden on the freeway the CDL engaged(need CDL switch mod), must be all the vibration and movements of gears. Once it worked I can cycle it freely with the switch, just need to remember to exercise it once in a while.
I guess you have the cdl switch? I have to shift the trans into 4lo and don't think I could get going that fast???? Anyway I was also able to hear the relay-but not the actuator- today so I may try to lightly malletize the actuator with a dead blow . That is...if I can get to it
 
Joined
Jul 26, 2012
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4,918
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SacTown!
I guess you have the cdl switch? I have to shift the trans into 4lo and don't think I could get going that fast???? Anyway I was also able to hear the relay-but not the actuator- today so I may try to lightly malletize the actuator with a dead blow . That is...if I can get to it


Yes I have the CDL switch and 7th pin mod. I really like the CDL switch me but on the fence about the 7th pin mod.
 
Joined
Feb 14, 2015
Messages
46
Location
NE Tennessee
Reelitchy --

Did you ever get your center diff working? I have the same issue as you. I bought a '93 with lockers that all worked initially. After a few times of shifting into 4lo the center diff light stopped working. I took out the fuse and replaced it and it worked again for one or two tries but now doesn't work. I do not get a light when starting or in 4lo but do hear the relay click. I don't hear the actuator. When I jump what I think is the CDL sensor (maybe its the L4 sensor??) the center diff light comes on and I can then engage the front and rear lockers. My next step I guess is to take out the sensor and see if I can get it working . . . Just wondering if you ever fixed yours.
 
Joined
Sep 23, 2008
Messages
55
Location
Southeast PA
I did get to work again. I had the connector at t case cleaned and checked for being in full contact and back to engaging. Hope this helps
 

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