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71 Blazer ignition switch problems

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by 71Blaze, Feb 19, 2007.

  1. 71Blaze

    71Blaze Registered Member

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    Hey guys,

    I need some suggestions asap if possible! The other day I came home from work in my 71 Blazer, turned the key to off and the engine kept running like I didn’t do anything. :confused:

    So, being the smart guy that I am, I went to NAPA and bought a new ignition switch. I installed it a few minutes ago, started the engine, let it run for a minute or two and then turned the key to off, and guess what? It kept running! Obviously the ignition switch isn’t the problem. :mad: I guess I’m not so smart any more!

    Has anyone had this happen before and if so, what did you do to fix it? This is my daily driver so I need to figure this one out quickly! Thanks.

    Herb
     
  2. Burt4x4

    Burt4x4 3/4 ton status

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    The power to the coil is staying hot with the key off...?? hmmmmm....No can't say I have heard that one...you could wire in a toggle switch to your power side on the coil but that would just be a workaround....wierd....:confused:
     
  3. bouncytruck

    bouncytruck 1/2 ton status

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    Try replacing the pig tail out of the back of the ignition switch. If your wiring has been monkeyed with, it might help.
     
  4. 71Blaze

    71Blaze Registered Member

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    I think I fixed the Blazer. To rule out the alternator, I disconnected all the wires from it, started the engine and then turned the key off with no luck, the engine kept running. So now, with my trusty $5 multi-meter in hand I decided to check voltage since the alternator wasn't the culprit.

    The first place I checked my voltage was at the fuse box and this is where I found the problem. There are a pair of red wires (one large & one small) in a single connector plugged into the spot labeled "Ignition Unfused." With the key off I checked that plug and no voltage. With the key on I checked and there was 12+ volts. I also checked the two red wires in case they were feeding the ignition system but they were dead. Before I plugged those two wires back in, I started the engine and then turned the key off and the engine stopped! I plugged the two wires back in and started the engine again but this time it didn't shut off with the key, so I reached under the dash and pulled those two wires out and the engine shut off. That's interesting. There was another spot on the fuse box that wasn't being used, I checked it with the m-m and it had 12+ volts when the key was on and 0 volts when the key was off. I plugged the two red wires into that spot and everything seems to be working like it's supposed to. Go figure? The two red wires have been in the Ignition Unfused spot since I replaced the harness and now three months later it does this. Weird. In case you're wondering, the stock harness had the two red wires plugged into the Ignition Unfused spot also, which is why I plugged the new harness in there.

    For now it seems to be working, but it still doesn't seem right. I'm going to keep diggin around with the m-m checking voltage. Who knows, maybe I'll find the real problem.

    Thanks for the suggestions.


     
  5. twosnvrlose

    twosnvrlose Registered Member

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    Since were talking about ignition problems my truck won't start until the the truck goes back in to the run position.So I have to crank it and let it go back into the run postion to get it to start anyone else have this problem?
     
  6. 71Blaze

    71Blaze Registered Member

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    That sounds strange. Maybe your ignition switch is bad. I thought mine was but obviously it wasn't.
     
  7. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    I had that problem after swapping in my 454. I had to eliminate the external voltage reg for the newer style alt. Ended up having the wires hooked up wrong and it would run off the alt after I turned key off. Doesn't sound like your prob though if you unhooked those wires.
     

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