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ignition switch?

Discussion in '40- & 55-Series Tech' started by atoyot, Aug 24, 2003.

  1. atoyot

    atoyot

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    "73 FJ40. Truck will run with key in the start position but as soon as I realease it to the on position it dies? Not a good thing to do I'm sure. Should the alternator check out when the engine is not running? Do I need to take it in to have it checked? Am I missing something. By the way I did check the tech links and the search engine. Also the radio still plays when the key is in the ON position so I guess that means the ignition switch is working I guess. I'm gonna have to try to figure out the wiring diagram but I just figured I 'd try to get all the help I could.
     
  2. hammerhead

    hammerhead

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    Re:Alternator?

    Doesn't sound like alternator to me.
     
  3. fsusteve

    fsusteve

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    Re:Alternator?

    Could be an ignition switch gone bad ???
     
  4. 73lndcrsr

    73lndcrsr SILVER Star

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    Re:Alternator?

    Verify the run circuit from your switch to the alternator, I think, I could be a loose connection. I don't have the book with me right now so I can't offer any wiring assistance.

    Sorry.
     
  5. JohnL

    JohnL

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    Check this

    Use a continuity meter and check your ignition switch. If you don' tknow how to do this, e-mail me.

    I had the same problem you have and was stumped bcause the switch was fine (even traded it out twice.) It turned out to be a bad starter solnoid. You may need a new/rebuilt starter.

    If it isn't the switch, take your srater out and bring it to NAPA and have them test it.
     
  6. atoyot

    atoyot

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    Re:Alternator?

    My starter is working fine. The engine starts up and runs great when the ignition switch is in start but when I release it to on the engine dies. So the starter is turning and the engine is starting.
     
  7. hammerhead

    hammerhead

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    Re:Alternator?

    If the contact in the switch is burned in the on position but not the start position the motor will start but die after releasing key back to on position.
     
  8. atoyot

    atoyot

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    Re:Alternator?

    Thank's Hammerhead sounds like you might be getting somewhere. So do I need to replace the Ignition switch?
     
  9. hammerhead

    hammerhead

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    My theory is find the problem then fix the problem. Don't buy a new switch you might not need. Your problem might be elsewhere. Test for voltage at the ballast resistor with the key in the on position. You should have full battery voltage at one end and a little less at the other end. If you want to do a quick check just bypass the resistor with a jumper wire. Connect one end of jumper to each end of resistor. If it runs with jumper in place then you know the resitor needs replaced.
     
  10. atoyot

    atoyot

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    What and where is the ballast resistor? I think you might be on to something. I didn't see it in my manual.
     
  11. hammerhead

    hammerhead

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    My book shows it on the coil but mine was on the fender (the PO cobbed the electrics). It is a ceramic looking block with a resistance wire inside that droppes the 12v down to a lower votage when running. The Ign. system only requires about 9 volts to function properly. When starting, the resistor is bypassed by a wire from the start circuit, feeding full battery voltage to the ign to ensure good spark during cranking.
     
  12. atoyot

    atoyot

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    I will try to find thid this ballast resistor tommorrow. A pic would be awesome or a discrition.
     
  13. hammerhead

    hammerhead

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    I looked in a parts book and it showed it on the coil also. The pics are lame B&Ws so they're about worthless. The ballast is about 3" long and made of white ceramic material with a bracket in the middle. There is a connector at each end. One end has a wire to the pos side of coil.
     
  14. JohnL

    JohnL

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    OK...try that and then check your starter again

    I understood your post already...that your starter starts it fine, but the engine cuts out when you release the key back to "run." Read this carefully: Even though your starter turns over fine and provides charge to your ignition when in the "start" position, you may still have a problem with your starter solenoid.

    Check continuity on your ignition switch. Clip one test lead to your "power in" terminal and check that you get continuity to your "IG" terminal on the switch when the key is rotated back to "run."

    Then check what Hammerhead says about the resistor (mine was on the fender of my 74FJ, but I don't use it anymore as I use a DUI.) If that doesn't work out, I'm telling you I had the EXACT same symptoms and it was a bad starter solenoid.

    Good luck.
     
  15. atoyot

    atoyot

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    Is this thing haunted?

    Okay I have good news and bad news. The good news is my wife was cranking the motor and I was testing the coil with the ohmeter. I didn't jiggle any wires and the truck just started running fine??? She thinks she fixed it...Anyway it's running great now but I din't know what was wrong with it. Also my horn wasn't blowing but the voltage was going down when you press the button so I disconnected the wire from one of the horns and the other horn starts blowing. Is this thin haunted?
     
  16. hammerhead

    hammerhead

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    Dude, you don't need a mechanic. You need an exorcist.
     
  17. JohnL

    JohnL

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    dUDE!

    Hammerhead...that's what you told me when I had that problem.....!!!!!

    atoyot - I also got that...it would be intermittent and eventually the starter totally crapped out on my. Luckily I was home.

    I hope you have better luck and it never happens again.

    John
     
  18. atoyot

    atoyot

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    So can I replace just the solenoid or do I have to do bothe starter and the solenoid?
     
  19. hammerhead

    hammerhead

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    The Ignition ballast resistor bypass wire gets its power from the solenoid ig terminal. It is contacted internally.

    JohnL - if my comment made anyone smile then I accomplished my goal. If you didn't giggle a bit then your sense of humor is short. Get that fixed! :D
     
  20. atoyot

    atoyot

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    I never did find the ballast resisitor. I heard it was a 3" long ceramic looking tube. I didn't see it.