1989 F150 w/ 302, one day it wouldn't start. I messed around with a few things and then took it to a local shop. The told me it was the ignition switch, changed it out and then told me they also installed a fuseable link because there was too much current and that's what blew the ignition switch. So now over the past week I have continued to blow the 20 amp fuseable link. Blew in the parking lot earlier today. Started driving and had the lights, wipers and defrost fan on low. Turned the fan to high and truck stopped dead in its tracks. Tonight I forced it to blow. Turned on everything one at a time: lights, radio, defrost fan on high, and then I got to the wipers and the 20 amp fuse blew. Frustration is setting in and I can only think I have to trace the entire wiring harness for damage. Anyone have any thoughts? Any help would be appreciated.

 

You should not have to add fusible links and depending where this link is installed, 20A may not be enough. Return all wiring to factory configuration and find yourself a different repair shop.

 

need more info ... what were these "few things" that you "messed around with" . you should be able to run every electrical item on high at the same time, without the truck missing a beat.
ditto what NotEnough said ... put things back to stock and stay away from that shop ... auto electric is not their strong suit.

 

I will remove the link this weekend and see if it blows the ignition switch. That's why I had left the fuse a me link in place

 

I didn't really do anything. Checked cable connections and put a multimeter on a few connections and checked fuses. I know just enough to be dangerous.

 

Wow. Real "professionals" working at that shop huh lol. If whatever YOU did was done correctly, you don't need to fuse the ignition switch at all since the branch circuits that feed it are fused from the factory. What was it that you did?

Also the shop should have at least used a replaceable cartridge fuse or better yet a circuit breaker. Fusible links are the ultimate in cheap... just one step above using things like this:

 

Well, there certainly is a possibility that a short circuit could, (not will) damage an ignition switch, but it certainly would be accompanied by barbecued wires and lots of smoke. So, lets assume that your ignition switch and wiring will function as Ford intended without any additional fuses or fusible links.

Your original ignition switch may have simply become faulty. It happens. We still do not know what you "messed around with", so it may be completely unrelated to your problem and the no start condition is coincidental.

Best advice, inspect to the best of your ability and drive it to see if it fails again. Bet it won't be the ignition switch!

 

The ignition switch is protected by a 20GA fuse link hooked to the starter solenoid from the factory.
Is this the fuse link you are talking about?

 

Just to reiterate. I didn't do anything just jiggled so wires to check tight connections, mainly by the battery and on the solenoid and wiring harnesses on the driver side front fender well. The fusible link was added from the battery to the starter solenoid mounted on the passenger side quarter panel, 20A. I am going to review the wiring tomorrow and look for burnt wires and harnesses. If I cant find anything I am going to remove the link that the shop installed and give it a go around the neighborhood to see what happens. Thanks to everyone for their thoughts. I will update later tomorrow. Keep the ideas coming if you think of anything else.

 

That would be paralleling a very heave GA wire so I do not think it would be there as if was it would never do anything.
Fuse link "P" going to C202 feeds the ignition switch and you can see it is 20 GA. I think you may be replacing fuse link "P".





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