wheel_of_steel

The car in question is my 95 Excel.







It had a flat battery after parking it overnight, so I bump started it and went on my way to work. After driving for about five minutes/two miles, the engine died and I coasted to the side of the freeway. Upon closer inspection, I found:



-the alternator fuse was blown

-with the ignition key set to 'ON', the check engine light wasn't illuminating, nor was my self-powered AFR gauge.



I figured there wasn't much else I could do at the time, the battery was almost flat, so I left it there. Does anyone have any ideas on how I can troubleshoot this sh*t? Googling around seems to tell me it's a short circuit somewhere, but that only deals with the blown alternator fuse.





Some background knowledge, don't judge me:

-Charge light was illuminating, but only when the rear demister AND the handbrake were both on.

-10amp dome light fuse kept blowing after I installed a second OEM trunk light. I got fed up with it and replaced it with a 15amp fuse two days ago.

-I've done a sohc to dohc engine swap, so I've fiddled with shitloads of wiring there, but it has given me zero hassles in the months that I've been driving it since the swap.

-I have also installed an AFR gauge and new instrument cluster, both required wiring but gave me no hassles and have been working fine.



Thanks for reading guys. The first thing I'm going to try is folding the remnants of the ALT fuse together, disconnecting the new trunk light and that fuse altogether, and bump starting it. PLEASE fire any and all suggestions my way.

majik

Remove 15a trunk fuse.

Replace ALT fuse.



rediagnose.

wheel_of_steel

Thanks maj, just got back from doing that.



-Bridged the ALT fuse together

-Removed 15a trunk fuse, removed second trunk light (turns out it was shorting on the frame, phew)

nothing changed, then

-replaced trunk fuse with proper 10a fuse



And nothing changed. All of the fuses are fine. I also disconnected the AFR gauge and inspected the engine bay wiring harness, nothing to report there.



The CEL still isn't illuminating, and now the battery is almost completely flat...

__________________________________________________ __________________________________



And just now

-Unplugged/reset the ECU

-Installed a good battery



And we're cranking with no spark, fuel pump, or CEL.







I'm going to jump down and grab my spare ECU and some tools, there's nothing else I can do with the factory toolkit.



*edited with updates so you don't have to scroll through a thousand posts

OTECTom

I would have the alt bench tested.

pas1216

but the alt shouldn't have anything to do with no start? Try the other ECU and report back.

faithofadragon

DO NOT JUST PLUG IN THE NEW ECU

at least not quite yet, its a good way to fry a new ecu since it sounds like you might have a short somewhere. test for a few things before you get there.



first, disconnect anything you have added recently, like the AFR thingy, until you figure out wtf is goin on. If you just recently started having problems, you gotta recently think of what you've done to it.



if you got a multimeter, test for a draw. if its strong enough to kill the battery that quickly id be careful not to fry the multimeter though.



ive heard you can do the same thing with a 168 bulb but have never tested it myself although i guess you can try it now, worst case you burn up a bulb



disconnect power cable off battery



separate the prongs of the bulb, run the prongs between the positive cable and the positive terminal



if the bulb turns on, you got a decent draw, keep pulling fuses until the bulb turns off.



then you can at least figure out what circuit is causing the issues and trace it from there





i dont think its the alternator causing the issues, ive seen some crazy things though, like on the wifes mustang a dead alternator for some reason caused the oil light to turn on (scared the f*ck out of us when we were driving at 80mph and the oil light turns on.....)



id get it all(battery, alt, starter) tested anyways. I donno if in upside down world they have places like autozone but they can test it for you for free while its still attached to the vehicle.



on the mustang, a bad coil once caused all this to happen:

burned up 1 spark plug wire

melted 1 plug

burnt up the wiring to 2 injectors

killed 2 injectors

killed ecu



although that was a strange, horrible chain of events



so dont just assume its just one part causing the issues if it is a short, test everything related once you find it to make sure it didnt damage anything else



next time you need to power something dont just add a larger fuse



use one of these:





i have 2 of them powering random things in the pile and they seem to be working ok

wheel_of_steel

Problem solvered! Cheers for the replies everyone.



The problem was in fact, the second trunk light that I had added. The back of the light was rubbing/earthing on the frame.











That's why it was blowing the fuses, and of course I was dumb and installed a bigger fuse. So I got back, removed that entire fuse and disconnected the AFR gauge, then replaced the ECU. It all runs fine now!



However, I think I cooked the AFR gauge somewhere along the way. It's a basic circuit with no surge protection or what have you, but hey. That's the price for stupidity.



Have some ass in return for all your helps

I really appreciate it and promise not to abuse any fuses in the future.

majik

if a fuse blows, that's merely indication of a problem. Don't avoid the problem by putting a bigger fuse in there

OTECTom

Sucks that something that small can cause all of those problems.



You should wrap the back of the socket in tin foil to insulate it from the body of the car.

majik

plz. don't do that.