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CDL light on startup

Discussion in '80-Series Tech' started by Ivan, Dec 30, 2003.

  1. Ivan

    Ivan

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    does the CDL Light on the instrument cluster definately come on at startup?

    and if so, will it come on at startup even if there is a problem with the CDL system?

    will the other 2 Diff lights on the instrument cluster come on at startup even if you don't have factory lockers?

    will a problem with the CDL system trip an error code?

    i'm trying to troubleshoot my CDL not locking in low on a stock 93 (without diff locks)

    i thought it might just need to warm up, sine the PO never used it, but now i'm thinking it may be broke. i'm starting with the CDL light on the dash because it doesn't light at startup. the fuse (14) looks fine and the connections on the t-case look fine. :'(

    any help appreciated.
     
  2. Beowulf

    Beowulf

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    Ivan,

    >> will the other 2 Diff lights on the instrument cluster come on at startup <<
    >> even if you don't have factory lockers? <<

    No, as there are no bulbs in the dash cluster.

    >> will a problem with the CDL system trip an error code? <<

    If you're asking if a CDL problem will trip the MIL, then the answer is no.

    -B-
     
  3. landtank

    landtank SILVER Star

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    Sorry Ivan but I have given you some bad info. First I was looking at the schematic diagram for my 96 which has ABS. After looking more closely it appears that the switch I mentioned on the other post isn't what turns on the light at startup but a signal from the ABS ECU. Just noticed your driving a 93 and none of this is relavant.

    Sorry

    I still think attacking the Dash indcator is the way to go. I wouldn't be surprised if once that is working the whole system will.
     
  4. Ivan

    Ivan

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    thanks for your help guys.

    my 93 has the ABS also if that matters.

    4L without the CDL locking is a real bummer. i got stuck in the wet clay really quick and my friend's 4Runner made it right up. the worn down scoripion AT's i've got probably didn't help, but i have to get this CDL up and working before i go to alaska this summer.

    i'll try to replace the bulb tomorrow (not even positive it's burnt out), and cross my fingers.

    the cruiser is my only transport, so if anyone has the bulb type, or part number for that CDL light, it would be greatly appreciated. i'd much rather go buy it, and then break the dash apart :)

    if i can't fix it, anyone know a good cruiser mech. in austin, tx?
     
  5. landtank

    landtank SILVER Star

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    Ivan here is a jpg out of my electrical manual. As you can see the switch I mentioned is Normally open so the bulb lighting comes from that line attached to ABS ECU. If the bulb checks out good then I'd go to IH1 pin 3 and short it to ground. The bulb then should light regardless of either the ABS ECU or the switch. That would let you know that the wiring that far is ok, the supply to the bulb etcetera is ok. Then it's off to the ABS ECU.

    Hope this helps.
     
  6. cruiserman

    cruiserman

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    IMO it's extremely unlikely the bulb is dead. Do you have a CDL switch installed? It won't light at startup unless it's locked. Do you get the ABS light on the dash with the transfer in low?
     
  7. landtank

    landtank SILVER Star

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    [quote author=cruiserman link=board=2;threadid=9417;start=msg82216#msg82216 date=1072827963]
    It won't light at startup unless it's locked. [/quote]

    I double checked mine today and it lights up when the key is turned to the on position and goes off 2 seconds after running. But then again I have a 96 but I'd think it's the same.
     
  8. Ivan

    Ivan

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    cruiserman-
    do, i don't have the CDL switch, and the ABS light has never came on in 4L. The ABS light comes on at startup, so i know it is good.

    i am also skeptical that the CDL light is the problem, but it should be easy to check as a starting place. i ran the truck aroung a gravel lot today for a while, zig zag, and reverse, etc. and no lights (CDL or ABS) at all.

    i just got the truck a few weeks ago and the PO never took it offroad. i had a pre-purchase inspection done on at, so i' really bummed that they didn't notice the problem.

    landtank-
    thanks for the diagram.
     
  9. cruiserman

    cruiserman

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    Ivan, Check to see if the plug on your t-case for the center diff lock connector has been removed. With the plug removed and no center diff lock switch, you will not be able to lock the center diff.

    BTW, I neglected to mention I was guessing about the CDL light at startup. I just checked it on my rig (1993), and it illuminates on the dash at startup if the center diff is locked; otherwise, it does not.
     
  10. landtank

    landtank SILVER Star

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    Cruiserman, do you have ABS?
     
  11. cruiserman

    cruiserman

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  12. ppc

    ppc M Go Blue

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    Slight differences in the 94 vs 96 EWD. The "from ABS ECU" in the 96 manual and "to ABS ECU" in the 94 manual. In either case the "center diff lock indicator switch" would provide a path to ground to iluminate the CDL dash light and to deactivate ABS lighting that light. If the ABS light comes on then the CDL dash light/bulb is not working. More than likely the switch on the transfer case is not working and would be easier to bypass than tearing apart the dash to check the bulb. There is a similar switch on the front and rear lockers you could swap to test. My rear locker indicator switch requires some TLC once a year to work properly. Looking at the EWD there seems no provision to flash the light when locking is attempted like the front and rear lockers. If you lock at those pages nothing really shows they do either but we know they do flash.
     
  13. phatairman

    phatairman SILVER Star

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    Anyway a digital camera owner can take a pic of the CDL switch on top of the transfer case?

    I have this same problem, the CDL and ABS not lighting up, but the CDL is locking up when I shift it into Low. The ABS light does light up on startup.
     
  14. Ivan

    Ivan

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  15. Ivan

    Ivan

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    today i lifted my truck and shorted the CDL switch that meets the t-case. that caused the CDL and ABS lights on the dash to come on. i'll replace the switch on monday and hope that fixes everything.

    i guess this means that if the switch IS BAD, then the CDL light on the dash WILL NOT light on startup.

    hope this helps anyone with a similar issue.
     
  16. landtank

    landtank SILVER Star

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    I might not be understanding your post but I think that the switch is fine. By shorting that switch you have tricked the system to think it is locked, this is good in that now you know the lights are functioning fine. After reading the schematic from ppc I can assure you that the light coming on at startup is do to the conection at the ABS ECU. That lock switch you shorted is normally open as when you are unlocked. Looking at my ABS ECU diagram you can see that there is a path to ground through a resistor. Then when the ABS ECU powers up it then applies 12vdc to that line to turn off the light. When the ABS ECU sees the activation of the CDL it then pulses that same line to cause the bulb to blink. Once locked the ABS ECU then turns on the ABS light. The switch you shorted acts like a latch/safety so that if locked at startup the ABS ECU will know that imediately.

    I would now start looking at the ABS ECU. Does the ABS light up on startup? If not check that fuse. It is probably in the engine compartment. It should be a rather large one.
     
  17. Ivan

    Ivan

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    landtank-

    i was just going by the tech post:
    http://www.sleeoffroad.com/technical/tz_centerdiff.htm

    it reads like if CDL is not engaging, then short the switch an the t-case, if that makes the lights come on then you know it is the switch...

    did i misunderstand?? now i'm really comfused.

    i thought this would effectively tell you that everything in front of that t-case switch was OK, and was a shortcut of sorts to checking all the wiring in front of that switch.

    my ABS light works fine (all the time) and the CDL light worked with that switch shorted.

    please let me know where i got confused :)
    thanks
     
  18. landtank

    landtank SILVER Star

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    I'm not 100% on your setup. I have a 96 and am going strickly by what I'm reading on the diagrams that I have and what was posted. Do you have a CDL switch on your truck? I don't as normal, I have installed one though. If you followed those direction exactly then It's the switch I'm sure.