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Ignition switch test

68bigblock

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I'm having periodic trouble with my 70 challenger starting, first time I noticed a problem I turned the key and nothing no crank or anything so I checked the battery cables they were good tried it again and it started, the next time I was driving it and it died the fusable link burnt up, replaced that then car cranked but wouldn't start, so I check the coil, ballast resister with a multi meter and they checked out fine never really touched anything, then tonight I went to do a spark check cranked it over and it started right up, so I,m thinking ignition switch is there a way to test it in the car? would a bad switch burn up a fusable link?
 

Adam

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Yes, you can check it in the car. Unplug the multi-wire connector at the bottom of the steering column and you can do simple continuity checks on the wires in the off, run, and start positions. There are wiring diagrams in the manual that show which wires you need to check. The ignition switch itself is just a simple switch activated by turning the key lock cylinder, it is not part of the key lock cylinder, so don't order that if you don't need it. You will have to pull the steering wheel & turn signal switch to get down to the ign switch if it needs replacing. Lastly, order a quality switch. Do not use one from a local auto parts store, they are crap.

And no, I don't think a bad switch would burn up a fusible link, but Im no electrician.
 
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moparleo

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Usually the only way to burn a fusible link is when you have a direct short. Which is why there is a fusible link to begin with. Just a fuse in the wire.
 
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68bigblock

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Did the continuity test and couldn't find anything in run or start positions but when I was unplugging the harness I did notice some discoloration on the supply wire(red) connectors they were getting hot. so I cleaned that up. There was a pour connection there but would that explain the crank but no start issue. its been working good since I went to do that spark test, I hate this periodic stuff
 

68bigblock

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it died again today, to keep it running I had to hold the key between run and start. when I got it home I checked the ballast resistor again and it checked out fine 1.2ohms, I have a new ignition switch on order. Anyone have any suggestions on what else I could check in the mean time?
 

Sixpaksteve

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I'm having the same exact problem with my 70 Cuda. It's very sporatic, but when it happens I have to hold the key between run and start to keep it running, just like you're doing. After 30 to 60 seconds of holding it, I can usually let the key go and the car will remain running. Other times I'll start the car, let go of the key as we all normally do when the engine fires, and the car will run just fine.

I think it's important to mention too that my car has never suddenly quit while sitting at a stop light or going down the highway. This ignition/key problem only seems to occur on the initial startup, and like most of you, my car sits alot in-between starts - maybe that's part of the problem?

I'm going to keep my eye on this thread to see what suggestions other FEBO members come up with.....
 

Chryco Psycho

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Could be an intermittent contact anywhere , but the ign switch is the first place I would look , if holding the key towards the start position helps it must be in that switch , plug on the column , bulkhead plugs are often problematic , I generally coat them with di-electric grease to prevent corrosion in the plugs
 

68bigblock

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I finally got the switch changed and the problem is still there, I have to hold the key between run and start to keep it running. is there any other ideas out there?
 

Chryco Psycho

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bad ballast resister , the power to the coil drops to 7 v in run position , if the ballast is bad there will be no power to the coil
 

68bigblock

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I tested the one in it and it tested good at 1.2 ohms but I changed it any way and no difference, even tried to jumper the wires on either side of the resistor and no change. the guy I bought the car from said he got it working by jiggling and taking the key in and out of the tumbler multiple times. is there anything in there that would shut down the car? everything seemed ok when I had the column apart
 

moparleo

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Did you try to start the car just using the ignition switch before you installed the key lock into the column ? This would eliminate the ignitions mechanical mechanism. If it still doesn't start we have an electrical problem. Diagnosing any problem is just a process of elimination. It can be a pain, but patience will reward you.
 
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68bigblock

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Did you try to start the car just using the ignition switch before you installed the key lock into the column ? This would eliminate the ignitions mechanical mechanism. If it still doesn't start we have an electrical problem. Diagnosing any problem is just a process of elimination. It can be a pain, but patience will reward you.

No I didn't, the old switch the plastic and metal part of the housing were separating so i thought for sure this was the problem and didn't look any further, but I will try that
 

68bigblock

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I pulled the switch out and tried it, and I had to hold it slightly toward the start position also, so it not the key mechanism it got to be electrical. I did a volt test across the ballast with the key on run I get nothing and with the key on start I get 4.9v and from the blue wire side of ballast to - coil in run I get nothing and 9v in start
 

68bigblock

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I was doing some continuity test and I noticed both ING1 and ING2 go to ground on the dash side of the bulk head (I unplugged the engine side) is that correct? and my manual says ING1 is Brown and ING2 is blue but every thing else says the opposite
 

Chryco Psycho

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ign 1 being start is brown , ign 2 being run is blue
you should have power into the switch with the heavy black wire & out with the blue & brown , none of these 3 should ground or you would have a short in the main power feed
 

Sixpaksteve

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My car is an automatic, so no Neutral Safety Switch there for me to check. I'm still curious to learn why this is happening to me as well and I appreciate the ideas and suggestions. :)
 

Adam

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On an automatic trans the switch is down by the linkage. I believe the middle wire just goes to ground, and the others are for the reverse lights... you can temporarily ground the middle prong with a jumper wire and eliminate it as a source of the problem. Of course this would only effect starting, not running.. btw, this is an easy way/place to put in a Kill Switch.


From an old post: Re: Neutral/park/safety switch question

"I was under the car messing around with my kickdown linkage. During the process the NSS plug fell off. I have been having problems with intermittent starting since I have owned the car and have always thought the NSS was the culprit. So I stick it back on without taking a good look at it and take it for a drive. It fell off again and there I was lying under the car sticking it back on at a filling station. Without a doubt I need a new NSS! However I was wondering how these stay on. Is it friction? Screwed? Tabs?"
 
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