Ignition switch wiring Q's

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Sep 17, 2007 | 01:54 PM

77f2504by4

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Joined: Jun 2004

Posts: 1,133

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From: Dracut, Massachusetts

Ignition switch wiring Q's

I'm having problems starting my truck. When I put the key to the on position no problems, but when i turn the key to start, sparks fly under the hood! The arc is from the brake booster to the bracket that holds it to the fire wall. There are no wires even in the area where the sparks are coming from. But it seems to me that something on the starter circut is grounding out. I thought maybee one of the wires on the ingnition switch plug may be the culprit, so i pulled the plug off the switch, only to find out all the wires on the plug show continuity to ground. Is this normal? Any other ideas on where I can look for bad wires? I'm very close to packing the cab full of tnt, lighting the fuse and running! Any help or insight would be GREATLY appreciated! Oh btw the truck is a 77 1/2 f250 4x4 with a 400 and a c6. if there is any more info needed just ask!

Thanks Bob

Sep 17, 2007 | 02:36 PM

blue68f100

Fleet Mechanic

Joined: Aug 2007

Posts: 1,804

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From: Piney Woods of East Texas

Check the connections at the soleniod and make sure nothing is shorting to chassis.

When you checked continuity is the battery connected?

Also check the ground cable and block to frame strap.

Sep 17, 2007 | 07:00 PM

turt

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Joined: Jul 2007

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I just have to say something about this site after reading your forum. I am an ASE Master Tech and I work at a GM dealership as the head tech. I drag race a mustang that I built and have a 79 F-150, 60 Impala, 65 Chrysler and 99 Jeep. I specialize in electrical and drivability and I must say that some of these questions and problems that I read about on this forum are TOUGH!!!!!! I had to laugh when I read yours...... You turn the key to start and sparks fly from the booster to the bracket????? I mean what the heck is that? I dont even know where to start? Anything I say would seem far fetched but I guess that is what your looking for. The good news is that these old circuits are simple. Im not sure how your testing for continuity but the answer is no, there should not be a path to ground on all the wires. To take a guess,,,,, maybe your start solinoid is shorted.