Interior Air/Heat controls not lighting up...KZJ78

Discussion in '70-Series Tech' started by OHnative7210, Mar 14, 2018.

  1. OHnative7210

    OHnative7210

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    Just noticed tonight that the backlight behind my interior air/heat controls won't light up every time I switch the headlights on...it's intermittent and I can't seem to find a way to keep those lights on. Not a huge deal but it does make it a pain trying to adjust the air at night.

    Anyone have any ideas where to start troubleshooting this issue? Thanks in advance!
     
  2. renago

    renago

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    Could be a fuse ?!
    Fuse box near the pedals on LHD .
    Maybe opposite on RHD

    Bye Renago
     
  3. Gun Runner 5

    Gun Runner 5 KI4CMQ SILVER Star

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    Mine does the same thing from time to time. I tap the faceplate and the lights come back on. I'm assuming a faulty connection somewhere.
     
  4. GTSSportCoupe

    GTSSportCoupe

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    I worked hard to replace those bulbs on mine when I first bought it. Worked for about a month and that was it, LOL. Must not be a great design, and the bulbs loose contact or something.
     
  5. OHnative7210

    OHnative7210

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    Well...not as hopeful as I was before! I have tried tapping the heck out of the faceplate, but no luck.

    This begs the question though...what other bulbs could be burnt out/have a bad connection that I am unaware of? I see this as a potential problem if something goes wrong and the light that's supposed to warn you doesn't turn on...

    With that, I noticed that there is a light that looks like the glow plug light on a tractor...the one that you have to wait for it to turn off before you turn the engine over. Mine never lights up...so I guess I am curious what the proper starting sequence should be as I have never owned a diesel aside from running a tractor.
     
  6. GTSSportCoupe

    GTSSportCoupe

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    Well, there are all the gauge cluster back lights, and indicator lights. There are lights behind the HVAC controls, and the buttons below (I think). Lights behind the buttons on each side of the gauge cluster hood. There should be lights below the shifter if it's auto.

    There is a light behind your glow indicator also. Maybe it's burnt out. It's easy to pull the gauge hood and check it. Honestly, the glow indicator is pretty useless as it turns off after about 1 second. I listen for the relay to open about 8 seconds after I put the key in the 'on' position. I start the engine when I hear that relay open.
     
  7. OHnative7210

    OHnative7210

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    GTS, I do the same thing...when I put it in the on position I hear a faint click. A few seconds later I hear a second click, then I start the engine. I think I saw a video somewhere that showed that sequence so that's why I was doing it. I am assuming that's the relay you're referring to.

    What's the risk if you just start it without waiting?
     
  8. GTSSportCoupe

    GTSSportCoupe

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    If it's cold out, or your engine is tired, it'll cough and smoke a bit on startup until it warms up.
     
  9. OHnative7210

    OHnative7210

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    I paid closer attention to the glow plug light...it does come on for a split second. Just never noticed that before.
     
  10. coldtaco

    coldtaco

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    If you really want to keep the glow system working like factory, then it sounds like it is time to start testing all the components of the glow system. You will need the manual. I know I have a different truck than you, but mine was doing the same, just a very short blip on the glow light. Testing showed one of the magic boxes did not test properly. So, I am just using the "Wilson" switch that the previous owner installed.
     
  11. GTSSportCoupe

    GTSSportCoupe

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    Glow control on the LJ78 is done by the main engine computer (ECU). Assuming it's the same for the KZJ78, but have not checked into it.

    At the end of the day, if the OP's truck starts good as is, I'd say leave well enough alone....
     
  12. JuanJ

    JuanJ

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    Hello,

    From memory:
    1. Speedometer, tachometer and gauges have one W5W bulb each.
    2. Indicators have one W5W bulb each.
    3. Odometer has a T5 bulb. It might be just me, but this one burns out before the other ones do.
    4. Brake/4WD/E-Hubs/High Beam/Door Ajar use one T5 bulb each.
    5. Altimeter uses two W5W.
    6. Heater and cigarette lighter use one T5 each.
    7. The panel below the heater controls has one W5W.
    8. Glow/Filter use one W5W each.
    You will have to take the instrument cluster out. Disconnecting the speedometer cable can be tricky.

    The green and black tabs in the picture are the bulb sockets.

    FZJ73 3.18.16 14.jpg

    Big tabs correspond to W5Ws. Small ones are for T5s.

    I do not have pictures of the heater controls.

    You may want to take the chance for a LED upgrade.

    Hope this helps.





    Juan
     
  13. OHnative7210

    OHnative7210

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    Juan, thanks a lot! This helps a ton and hopefully will help anyone else who's in my boat. I agree with the LED upgrade idea...I'll have to start looking into bulb options. LEDs would really make driving at night a little better, the incandescent bulbs are really dim and LEDs would give it a fresh look. Thanks!
     
    JuanJ likes this.
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