DrDirt

OK, my office manager's '97 Grand Marquis 4.6L is blowing fuse 16. Electrical gremlins is not my thing so could use some guidance. It has to be a dead short somewhere but where? It instantly blows when you hit the key. I don't see any obvious shorts in the wiring. Have checked the ignition switch on the steering column. It is clean, with noburn marks, not smoke stains etc. Swapped out the relay for the PCM...still does it. Where shoul I look? FPR?

Iraq&Roll

How big is the fuse and what is on it? (just curious is all)

GNs-r-slow

Id still swap the ign switch....they dont have to look like theyve been on fire to be bad

DrDirt

It's a 30 amp fuse and yes, I'm trying to convince our fleet mechanic to change out the ignitiion switch anyway. The owner had trouble starting it yesterday leaving work...let it sit a minute the tried it again and it started...shut it off and restarted 5 mmore times with no problems. She left for home and then it just died on her on the street. Towed it back here to work.

cjackson2802

I know on the foxbodys, the fusible links are such a headache! But I'm not sure if a 97 grand marqui has them. lol

DrDirt

I would think that a fusiblelink would blow before the fuse...but who knows. I never did get a chance to stick my head under the hood. I was just giving hints to our fleet mechanic. While I was picking up test samples from a client, they had the Merc towed to a shop. Oh well....

Thanks for the suggestions, guys. I guess we'll just have to wait and see what the "professionsls" come up with.

DrDirt

For the purposes of closure in this traumatic event and future reference. It took the pros 4 hours of diagnostics to locate the problem so I don't feel so bad at having not found it in my 20 minutes of hands on time. The culprit was the rear HEGO. Seems the harness had rubbed a spot thru the insulation on the heater wire and the beyotch shorted out. There ya go carb guys...more fodder.

GNs-r-slow

Rear hego? engrish!!

DrDirt

Damn carb guys, grumble, grumble.

HEGO = Heated Exhaust Gas Oxygen sensor.

Rear = The behind one.

Short = Let all the smoke out.

Office Manager = $240 lighter

GNs-r-slow

Yep no HEGO on a carb deal....1 more part that makes me stick with a carb.