1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Center Diff possible problem

Discussion in '80-Series Tech' started by Gregb, Jan 27, 2004.

  1. Gregb

    Gregb

    Messages:
    11
    Likes Received:
    0
    Joined:
    Jan 27, 2004
    I purchased a cherry 94 LCC last week with 98k miles. It has the standard center diff lock but no front and rear lock.

    Probably never been off road. When I put it in 4L nether the center diff light nor the ABS light come on. To test it, I put it on 4 jack stands, and when in 4H the front and rear wheels both pull, but when I stop the front wheel by hand only the rear wheels pull. Normal of course. When I switch to 4L and try this I cannot stop the front axle, so this tells me the center differential is working normally I believe. Am I wrong? The dealer said the light was not supposed to come on, but he was wrong of course.

    An opinions?
     
  2. Hltoppr

    Hltoppr

    Messages:
    2,024
    Media:
    4
    Albums:
    2
    Likes Received:
    8
    Joined:
    Aug 29, 2002
    Location:
    Port of Indecision...otherwise Northern Arizona
    Light is supposed to come on for both the center diff lock and the ABS. Dealer was fibbing or just didn't know what he or she was talking about.

    Can you hear the center diff lock engage? Usually there is an audible "click" when it goes in and out.

    While I haven't personally tried the "stop by hand" technique, I somehow doubt that it would help much, but I could be wrong.

    -H-
     
  3. landtank

    landtank SILVER Star

    Messages:
    18,919
    Likes Received:
    1,069
    Joined:
    Mar 27, 2003
    Location:
    Groveland MA
    Sounds right, are you under a vehicle with the motor running in drive? There is a switch on the T-Case used to tell the various components the t-case is locked. Go to www.sleeoffroad.com in the tech section for what to do about it.
     
  4. e9999

    e9999 You want to do what...? Moderator

    Messages:
    16,579
    Likes Received:
    477
    Joined:
    Sep 21, 2003
    Location:
    US
    oooh yes!
    put it on 4 jacks, run the engine in drive and low gear, lie down underneath, and if you position the truck correctly, say in front of a major window or wall, you'll make America's Funniest Videos in no time :D (or -heaven forbids- the Darwin award... :'( )...

    :D :D
    E
     
  5. semlin

    semlin discouraged user

    Messages:
    5,222
    Media:
    1
    Albums:
    1
    Likes Received:
    771
    Joined:
    Mar 27, 2003
    Location:
    north of 49
    The wheels turning test sounds a bit scary to me but it does sound like the diff is locked, but I am suspicious that neither dash light comes on. You do not want the ABS trying to work when the diff is locked. Do the lights come on when you turn the ignition on without starting?

    You could try ordering the central diff lock dash switch (new from sleeoffroad.com or used from cruiserparts.net). This would be part diagnosis, part cool modification.
     
  6. sjcruiser

    sjcruiser

    Messages:
    834
    Likes Received:
    3
    Joined:
    Apr 3, 2003
    Remember, the power output is doubled in 4L - so it's possible that you cannot stop the wheels from turning by just grabbing it.
    I could idling up my inclined driveway in 4L, but not in 4H.

    Frank.
     
  7. ppc

    ppc M Go Blue

    Messages:
    1,798
    Likes Received:
    408
    Joined:
    Aug 18, 2003
    Location:
    Nashville, TN
    The adding the CDL switch isn't going to do much to diagnose the real problem.

    Attempt to lock the center diff, put in gear drive back and forth and make some turns. If your still on the jack stands this shouldn’t be necessary. Shift it back into park, shut the motor off but turn the key back to the on position without starting.

    First crawl under the truck and pull the connector of the front of the transfer (CDL Indicator switch). Short across the pins on the harness and look to see if the center shows as being locked (dash light glows). If is doesn't light then you have a wiring issue, burnout bulb, or blown fuse. If it does you know that from the harness forward is functioning properly. You can remove the switch on the front of the transfer and test it for proper on/off functioning with your multi-meter.

    If you still have not identified the problem pull the connector of the right rear of the transfer (L4 indicator). If you short across the connector you should hear the diff lock motor running. One side of the connector (yellow wire) should have 12V supplied to it. If no voltage is read, suspect a blown fuse or wiring problem. If voltage is present and no motor sound there is a problem with the CDL motor or wiring to it. If you hear the motor sound then pull the L4 switch and test it for proper operation with your multi-meter. If switch tests out OK then there may be a defective diff lock ECU or more wiring issues.

    The switches can be worked while spraying them with WD40 etc to restore there operation in some cases but it my be only a temporary fix. The diff lock motor can be directly run with a good strong 9V transistor radio battery.

    Let us know what you find.
     
  8. Gregb

    Gregb

    Messages:
    11
    Likes Received:
    0
    Joined:
    Jan 27, 2004
    Thanks to all for the tips (except the Funniest Home Video crack, of course I'm not under the vehicle with the wheels turning, jeez!). The ABS light comes on and goes off at startup, and I tried another idea, put two large floor jacks under rear wheels, lifted both back tires off the ground 1 inch, put in 4H, vehicle didn't move, rear wheels spun. Put in 4L, front wheels pull vehicle. That tells me center diff has to be working. I'll check the connections for the indicator and other tips. Will let you know what I find.

    Thanks.
     
  9. landtank

    landtank SILVER Star

    Messages:
    18,919
    Likes Received:
    1,069
    Joined:
    Mar 27, 2003
    Location:
    Groveland MA
    Greg, it's probably the switch on the T-case. I beleive it's the one up front on top.
     
  10. Gregb

    Gregb

    Messages:
    11
    Likes Received:
    0
    Joined:
    Jan 27, 2004
    Thanks Rick. Based on what I read on Sleeoffroad (thanks for the link!) I think you are right. I'll test the switch later today.
     
  11. Gregb

    Gregb

    Messages:
    11
    Likes Received:
    0
    Joined:
    Jan 27, 2004
    Problem solved. It was the indicator switch. I removed it, cleaned it, activated it manually sevaral times, reinstalled it and now it works perfectly. Internal contacts were probably bad due to lack of use. If it goes out again I'll replace it.

    Thanks for all the advice.