electrical problems *winces*

[Pirate_Freder]

sorry this is so long but I wanted to make sure I got all of the info in.

sooo....as i have stated before i just got a 1993 240SX Coupe on Tuesday. The guy had some wire hooked up to the positive and running through the firewall(I'm assuming it was for speakers cause i saw smoke in the trunk;I'll explain in a second). On Friday i went to the carwash(~5 min. away), proceeded to drift my way out of there then stopped at the gas station across the street.

Once I got to the gas station it gets a bit blurry(was frantic) but I think my electronics started weirding out or something so I shut her off and popped the hood....that blasted wire had moved itself around and was resting on the negative terminal.....so yeah, melting, smoke etc. I popped the trunk to look for a 10mm for the terminal and saw a bit of smoke as i was digging around(assuming it was from the loose speaker wire back there but i was too frantic too tell cause i thought it came from the metal). Anywho I couldn't find the wrench so I ran inside and asked for pliers so i could yank it, no dice...so i ran back out and tapped the melting wire really quick to see if I'd die from grabbing it lol, seemed good so I yanked it out of the positive terminal with a rag.

Lots of jumper charging and cranking later still no combustion. I got a battery the next morning cause mine tested kinda medeoker. I also found my "ENG CONT" fuse to be blown. No one in town has one so i ordered one. I later realized the fuse for the headlight motors was exactly the same though so i put my headlights up and put it in the ENG CONT spot. THE INSTANT I put the negative back on it blew...doesn't even look blown though i saw the flash and it doesn't work for the headlights anymore.

so...I suppose there must be a short somewhere after the fuse? what all runs off of that fuse? I don't think the wire that melted cause any problems directly; only things it could have touched seem to be the fuel filter and the chunk of wires running back by the passengers front wheel well.

any ideas as to what shorted? maybe something besides a short?

ThanksFred

[vancouverbc]

eng cont is just a standard 10 amp fuse. should be avail anywhere auto parts stuff is sold. should be extra ones in fuse box in driver kick panel.

eng cont fuse supplies power to air injection valve solenoid. (disconnect and see what happens). aiv is not important for running of car. it also supplies power to engine check bulb relay which is under driver dash. i think this is the check engine light bulb. forget what the relay does.
Modified by vancouverbc at 1:06 AM 5/9/2007

[vancouverbc]

zerothread/231424

the first post is a photo of my fuse box inside car by driver kick panel. you can see two extra fuses stored there.

[vancouverbc]

This pic shows aiv in car with hose to filter box disconnected. This is the best way to deal with aiv. just disconnec the one hose at filter box. this is where it gets its air. keep the aiv because you may need for pollution control laws. it only reduces pollutants by small amount.



another pic of aiv:

This pic shows electrical plug to aiv solenoid. circled in red.

[Pirate_Freder]

ohhhh, that's what that weird little ribbed bocx is about...what does that thing do anyhow? well i will try that tomorow.

on another note though....my eng cont is 25A...soo...maybe mine is running more than that?

EDIT: I looked at your fuse pics and what I am talking about is the one next to the headlight motor fuse(ret mtr).

[vancouverbc]

Ok, the brown 25 amp fuse link would be harder to find. It sends constant power to the 4 fuel injectors(red wire). It also supplies constant power to terminal 46 of ecu(red wire). it also supplies constant power to the eccs relay(called egi). disconnect the eccs relay and see what happens. if the short stops when you disconnect the eccs relay, you have problem with eccs relay or the wiring past eccs relay which goes to a lot of places. if short continues with eccs relay removed, you know short is with injector wires or terminal 46 or wires going to eccs relay.

re eccs relay: It is a green relay and is in the same relay box as eng cont fuses. It is called egi(electronic gas injection). it sits next to another green relay called egi pump(fuel pump relay). these are both same type of relay so you can exchange them to see if symptoms change.

re AIV: it injects filtered air to burn up more pollutants but it bearly makes a difference. nissan stopped using it.

[RedSVTFlareside]

Electiricy hates me too. Good luck man.

[Pirate_Freder]

well on the subject of shorts....i tested the amperage where that fuse goes in(with the battery conected of course) and it draws about 1.5MA, in other words nothing. yet the insant i put the brand new fuse in it blew....so why would my multimeter read almost nothing but then the 25A fuse goes boom...

[vancouverbc]

well on the subject of shorts....i tested the amperage where that fuse goes in(with the battery conected of course) and it draws about 1.5MA, in other words nothing. yet the insant i put the brand new fuse in it blew....so why would my multimeter read almost nothing but then the 25A fuse goes boom...

How can you measure amperage without the fuse in the circuit? You dont have a complete circuit. Look for voltage drop in the wires to find short.

[Pirate_Freder]

well i figured that if i tested at where the fuse plugs in i would be completing the circuit with my multimeter. would i just use a gtround or the negative terminal for the negative to test voltage? (since there is only positive running through the circuit)

[Pirate_Freder]

well i believe what happened is that wire was next to the harness going into my ecu and that caused a short. it didn't seem like they actually melted enough there but who knows...would it be safe to solder one of my blown fuses? cause i think it could work now but yeah...i'm afraid and it will take a while to get another one. also where can i get a bunch of those fln or pal style fuses for cheap?

[vancouverbc]

well i figured that if i tested at where the fuse plugs in i would be completing the circuit with my multimeter. would i just use a gtround or the negative terminal for the negative to test voltage? (since there is only positive running through the circuit)

There is only positive but there is a short which will reveal itself as voltage.If you take voltage readings along the wire there should be zero voltage reading. However, if there is a short , there is a difference in potential which will read as voltage on your multimeter.

You might get some of those fuses at a junk yard. Not safe to solder them.

Im not too sure about the amps. Have not done this for along time. wouldnt a short blow the fuse in the multimeter. Or, if you didnt use the fuse you might have blown multimeter?

[Pirate_Freder]

but how can i test for voltage without the fuse in? there is no power to the circuit sooo...

in terms of the fuse on the multi-meter, it still reads voltage just fine so i would assume it's good.

[vancouverbc]

Do a continuity test if there is no power in circuit. ie measure for resistance. The short will show as resistance.

http://www.exide.com/products/...d.pdf

[Pirate_Freder]

got it running yesterday. the wire that shorted was bonded to the ecu harness so it was drawing from it and grounding somewhere. got my butt into gear and pulled it out finally lol(could have been a lot easier if i had just pulled it first thing :P). she's running great now, a few kinks here and there but i'll get it all working great.

also, in terms of removing the AIV: where can i get a plug for the header where the AIV hooks up?

thank you so much for all your help everyone

[vancouverbc]

I bought a package of assorted rubber plugs/caps and the white filter from canadian tire in canada so you can probably get them lots of places. If you are taking the whole thing off, you need a plug for the exhaust. I have been using a rubber cap for that too but had to clamp it on for it to stay.

[Pirate_Freder]

iunno about you but i'd be a little bit afraid of a rubber cap melting lol. i was hoping there would be a weird little bolt/plug that would go in there.

[vancouverbc]

iunno about you but i'd be a little bit afraid of a rubber cap melting lol. i was hoping there would be a weird little bolt/plug that would go in there.

I think there is a thread about a metal plug for it. My rubber cap has not melted in a year but it will come off without a clamp.

Im using the same clamp that clamped the rubber hose to the pipe. the cap is made of same material as rubber hose that used to attach to metal exhaust pipe.
Modified by vancouverbc at 1:51 PM 5/13/2007

[Pirate_Freder]

well a searching i shall go then