Another fusible link / electrical gremlin post...

[TLCandME]

Any help appreciated!!

My son had to jump the '97 and I'm guessing something went wrong.... he got the car started but it left him stranded on the way home.... starter would turn but engine would not start. Searched forum and discovered the fusible links. Also upon inspection, the negative battery post was severely damaged as in it looked melted.

Replaced the fusible link (ordered two)... and put a new battery in. All seemed good but on first drive, the fusible link blew again.... the wire to the gray plug... I think Am2... same fusible link both times. Wired in an inline fuse to save the second fusible link for when I get this figured out. Put in a 5 amp fuse.... and they keep blowing... but car runs normally immediately after new fuse put in.

So my forum search would suggest there is a short but I don't know where to look to find it. Could it be the negative battery cable? That's where all the damage was after he jumped the vehicle. The guy at Autozone said he had only seen that when the jumper cables had been crossed.

Search says the short is downstream from the link... is the negative battery cable downstream?...

Hope that's enough info.... need help troubleshooting... THANK YOU!!

William

 

[Tools R Us]

Usually when the jumper cables are hooked up backwards, it only blows the fusible link. When it wont start, with the key turned to run, is the CEL on? The default check is the engine wire harness contacting the EGR pipe, if so tie it back from the pipe.

 

[george_tlc]

Answering some of your questions.

The fusible links are on the POSITIVE post of the battery. There entire body/chassis etc is ground.

Any positive wiring short to body/chassis will blow a fuse or fusible link, all depends on the particular positive wire (i.e. whether there is a fuse protecting that wire or only the fusible link).

A 5A fuse is way too little to replace a fusible link for testing. Most of the links are in the 50 to 100A range. Other than the starter motor, your entire battery current flows through those 3 fusible links to the rest of the electrical system.

As Tools mentions, a common shorting area is the harness (with the injector/tps/iac etc wires) by the EGR valve. The clip that keeps the harness away from the EGR (HOT) valve breaks and the harness can rub (melt) and short against the EGR valve (ground). As the motor moves on the engine mounts as you drive/accelerate etc the short can intermittently occur.

Another possible spot for harness shorts is behind the glove box where the harness runs to the ECU and can be too close and rub on the sharp metal that is goes by. This is a problem on some 80's while on others the factory routed the harness safely away from the sharp edge.

cheers,
george.

 

[TLCandME]

Thank you both!! I read about the EGR location and shorting against the harness.... but I was focused on the negative battery terminal because of the obvious damage there when I inspected the battery. I will put a bigger fuse in.... the fuse was just to be able to move the car and save my spare fusible link while we worked this out.... the first time this happened, I didn't know about running a "jumper" and had to shell out for a tow truck.

I will check the harness at the EGR location tonight.... thanks for all the help in keeping this rig running.... I've taught myself a lot by you guys teaching me..... THANKS!!

 

[TLCandME]

Y'all nailed it .... three wires in the bundle were shorting against the EGR valve... that big metal nut had backed off the threads of the pipe and were making contact with the wires... hopefully the issue is fixed.... liquid electrical tape, followed by electrical tape followed by some sticky heat shield wrap I found at Autozone and zip ties to replace the missing / broken retaining clip.... Thank you all!! Put the spare fusible link in and no more issues.