I know I'm brand new, but this is urgent concern!

[kewandnout]

I just bought an 85 Mr2 and the battery happened to be dead the second time I tried to drive the car. So I went to Walmart and bought a replacement.

Just to let everyone here know, this is the first time I have ever tried to install a battery.

So I replaced the one in the car with the new one. I connected the wire with the red plastic boot/hood to the positive battery terminal. Then I attached the black boot/hood wire to the negative terminal.

I had to force one side on as it didn't quite fit on the terminal. That's when sparks started coming off the terminals. Then it really started smoking. I was really freaking out so I thought to myself, maybe these wires are strangely mislabeled.

Turns out that WAS the case, the RED boot was on the NEGATIVE wire and BLACK on POSITIVE!! Now how or why someone would switch the two is totally beyond me! I looked to see where the wires attached to on the car just to confirm that the red was in fact the NEGATIVE and the black was in fact the POSITIVE. The black wire sure enough was going to the engine and the red was going to the body of the car. Very very strange.

So I returned the battery to Walmart, got a new battery and installed it. Still no electric power to the car. So I went out to Pep Boys and bought completely new fuses and replaced all but one which I couldn't pull out of the fuse box in the engine bay. STILL no power. So I'm confounded right now, I don't know what more I need to replace to get this car back and running again.

Should I buy a new alternator? If not, what do you think would do the trick to fix this mess?

What should I do now? Please help me out here !

[328FTW]

Start with basics like checking the earth to the body is still sound and that everything still has insulation so there are no more shorts. Once you have verified that start checking for burned out connectors, melted wire, fried joins. Once you have done that start checking for hardwired things that still work like horns and things separate from the ecu. After that you can look at each system once you know you have power and figure things out.

Also lol at returning battery.

[BrandoMKII]

Well I can't see reversing the current in your car being a good thing but it shouldn't harm anything but the battery. I would just check the alternator and make sure its still working properly. Even then, your electronics should still work as long as the battery does.

[328FTW]

Originally Posted by BrandoMKII

Well I can't see reversing the current in your car being a good thing but it shouldn't harm anything but the battery.

Ecu, ignitor, distributor, auto trans computer, alternator dash wiring..........

There's more than you think, ususally its not that bad but it can be just the luck of the draw if you can call it luck.

[como]

if you turn the key and theres no ACC power (no lights on the dash?) then its probably a fuse.
Heck, check the fuse box with a multimeter to see if the fuses are getting 12v, even. theres something called a fusable link you may want to look into as well. (Pretty sure you already did, seeing as how you hit up that old thread)

[Medusa]

The little electrical gremlins could hate you too.

I would take that multimeter and check every wire you can for a short, after the easy checks like turning the ignition to ON and things like that. I am assuming you checked all three fuse boxes? After that, check fusible links and then chase out the shorts if you still aren't getting power.

[MR JAS]

hmmm how did you get to return it
they must be dumb at walmart
i work in a car parts type store and the worst i saw was a women that (tried to) return a battery that was a different brand from a competators store at the other end of the country she had hooked the cables up backwards and left in on so long the positive terminal was completly gone just a trail of melted lead along the top of the battery left

needless to say she was pissed we wouldnt replace it lol

[Raptor13x]

I had this happen to me once. I attached red to positive and black to negative, not thinking anyone would be stupid enough to screw with common sense, and it killed the battery in seconds. Stranded me too. Luckily, after installing a new battery, nothing appeared to be broken.

[Sylvan]

One time I did this (hooked up jumper wires to the wrong terminals), and in addition to blowing a fat fuse, it also fried my igniter.

[muffinman]

+2 for fusible link

[BrandoMKII]

Originally Posted by 328FTW

Ecu, ignitor, distributor, auto trans computer, alternator dash wiring..........

There's more than you think, ususally its not that bad but it can be just the luck of the draw if you can call it luck.

I don't think so. your car battery is Direct Current, it only allows energy to pass threw one direction. so if you hook the battery up backwards, nothing should happen. All you would be doing is sending energy threw the ground
cable to the frame of the car the negative end of a battery doesn't do anything but complete the circuit.

[328FTW]

Originally Posted by BrandoMKII

I don't think so. your car battery is Direct Current, it only allows energy to pass threw one direction. so if you hook the battery up backwards, nothing should happen. All you would be doing is sending energy threw the ground
cable to the frame of the car the negative end of a battery doesn't do anything but complete the circuit.

Yes but it can earth through circuitry such as the ecu and ignitor and things like that. I've seen some serious fry ups on some cars that have had the battery put in backwards. I'm not just throwing parts out there I've seen all those things fry (especially when putting in high amp batteries), can also set off airbags and do other such things as well. Hell I saw a battery explode once from the hydrogen igniting turning it into a bomb.

[David]

This reminds me if how stupid GM is, and my lack of experience with GM. My dad has a Lumina in his dealer, and GM has a retarded washer fluid resevoir that goes directly above the battery for some reason that beats me. So, you can't access the battery terminals at all. It has one relocated terminal at the top, and I thought that was ground. So I took a battery charger and put the ground clamp on the relocated terminal, and I managed to stick the positive to the positive terminal on the battery. A **** load of sparks flew for the .00000001 second I had it on, but no fuses blew, and nothing went bad. Lucky me I guess.

[Jackstand Queen]

I've never noticed the presence of a FUSIBLE LINK in an MR2.

Generally speaking, its an average sized Black wire which runs near the battery and has sort of a coin sized module in the wire.

Fusible Links are designed to protect components and auto-destruct when a battery is hooked up in reverse polarity. A new fusible link may be needed, if the Mr2 has one.

[te51levin]

Originally Posted by kewandnout

The black wire sure enough was going to the engine and the red was going to the body of the car.

If your car still has its original positive and negative cables, positive will be black with a blue tracer (stripe), and will disappear into plastic split loom. Negative will be black with a yellow tracer, and will go to a bracket on the left strut tower, then continue to the transmission case.

Originally Posted by kewandnout

So I went out to Pep Boys and bought completely new fuses and replaced all but one which I couldn't pull out of the fuse box in the engine bay.

There's a big square yellow one with a clear lid in the engine bay fuse block. It is held in with a bolt. If that fuse has blown, the bolt can be accessed (barely) after removing the EFI main relay, which looks like a round silver metal canister.

Originally Posted by kewandnout

Should I buy a new alternator?

No no, definitely not. Don't buy anything yet. Get a shop manual and a buddy who owns a multimeter and knows how to use it. This will allow you to trace circuits and make sure you have power and continuity where you need it.

Originally Posted by como

Theres something called a fusable link you may want to look into as well. (Pretty sure you already did, seeing as how you hit up that old thread)

Exactly right. Again assuming your wiring is original, this will be a black wire inside a gray plastic sleeve, and it runs alongside the positive battery cable and attaches to the positive battery terminal with a large ring terminal. This fusible link handles ALL of the electricity between the battery and the car (except for the starter motor), and if it is blown, NOTHING will have power. It will probably feel pretty brittle and crispy if it has blown. This is where that 16ga fusible link wire you asked about in the other thread comes in . You can use that to replace a burned fusible link. Be sure to do a permanent, professional repair - this is no place for twisted-together wires and electrical tape. Crimp and/or solder the repair and use heat shrink tubing.

Good luck!

[MR JAS]

when all is said and done go see the previous owner and give him/her a backhand slap

[GrandpaGofast]

Hell, it wasn't even my thread and I learnt some good info.
All the best,
Grandpa