Hey guys, I had to install a new battery today but unfortunately I did it when it was dead of night and I couldnt see a thing. Anyway, I ended up hooking up the new battery backwards. That was a BIG mistake. Huge spark and I heard something pop around the ignition coil, distributer area. I have no idea what blew but when I hooked it up the correct way the car engine turned over but died right away. In addition to the engine dying right after start-up, the radio doesnt come on. So my question is, if a person were to be stupid (like me) and hook up a battery in the dead of night and hook it backwards, what would be the first things to blow?

First thing to do is check all the fuses under the dash and replace the blown ones.
Next check the ignition coil to distributor harness.
Next check the fuse links, If they are not blown, You may have one or two that cooked a little and now has bare wire showing.
Finally, Pray the ECM fuse blew before the ECM did.

(Don't ask how I know..... No it wasn't my Fiero..... )

[This message has been edited by Oreif (edited 04-02-2004).]

when you say fuse links do you mean all the slots under the dash? I checked all those fuses and they looked fine. I will look more in the morning. I just cant figure out why the radio wouldnt work. Everything else makes sense except that.

quote Originally posted by 1987 Trans Am: when you say fuse links do you mean all the slots under the dash? I checked all those fuses and they looked fine. I will look more in the morning. I just cant figure out why the radio wouldnt work. Everything else makes sense except that.

No, A fuse link is a smaller gauge wire at certain points in the harness. They are near the battery. There is one for the starter, one for battery power (to the inside of the car), one is on the accessory power line and one is up front for the headlights. Most likely the battery power one blew. You should have no radio, lighter, horn, or interior lights. If you have interior lights, horn and lighter, then you blew the constant power in the radio.

Basically you need to start checking everything electrical. It's a nasty thing when batteries go in backwards.

The other problem is once you get the car running and everything working, Expect a few things to act up or die later on. Took me 4 months before the car ran fine without any hiccups.

[This message has been edited by Oreif (edited 04-02-2004).]

I have interior lights but I have not yet checked horn or lighter. Would the battery fuse still be something to check?

If you want to make sure your ecm is okay, turn the ignition to ON without starting it. The check engine light should come on, and the fuel pump will come on for 2 seconds, then shut off. If this does not happen, your ecm might be dead, or not getting power.

Btw, the enigne will still crank with a bad ecm, but will not run.

check engine light does come on when key is turned to 'ON' position and fuel pump does run.

So it sounds like you killed the radio and you need to check out the distributor and ignition coil.

What about the distributer and ignition coil should I check? Anything else to look for or is that pretty much narrowing it down?

Ignition module inside the distributor, coil, pickup coil, tach filter are about the only things in that area. Also check for ground wires that have been vaporized. Does the car turn over?

Basically, it has to be something that is always connected to the battery, anything that gets power with key on will be ok since this happened as soon as you connected the battery (I am assuming the key was off).

Tim

interesting isnt it?

Tach filter is a capacitor used for filtering out noise generated by the motor - feeds back to the ECM and tach - little silver canister mounted near the coil. Probably ok, since the key was off.

You could also try pulling the EPROM out of the ECM and try starting the car and see how it runs in the factory default mode (maybe the EPROM was damaged)?

Any codes??

[This message has been edited by Mickey_Moose (edited 04-02-2004).]

bump yet again

If the ECM does not flash a code 12, then it may be toast.

I believe ECMs are available as reconditioned over-the-counter parts. I would first post a "wanted" add in the mall section. Lots of folks have parted-out cars and the ECM is certainly something one would save.

First I would say it is the coil, and second it is the dist. module. As far as the radio you may have blown a resistor or something.
also check the pigtail connector at the battery. It will be one wire comming out of the harness with a weather pack disconnect. this feeds the memory in the ECM.
Don

I'm kind of leaning toward the ECM, especially since the check engine light doesn't come on at all.

Someone correct me if I'm wrong...
When the car is first started, doesn't it run on the ignition module until a certain RPM is reached?
Also, doesn't the cold start injector supply enough fuel to run the engine for just a couple of seconds?

I could be mistaken on those points, but the ECM has a constant battery supply, as does the radio.
If it's hooked up backwards, it can get really unhappy. (Check the ECM and injector fuses again, just for grins.)

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Raydar
88 3.4 coupe...........

Coming soon...
88 Formula, presently under the knife.

I pretty much did this exact same thing, except I was moving my battery up front, and had two cables that were the same color. I sprayed one end red, after following it from the starter. I guess I marked the wrong one. Everything in my car works, except the radio. My headlight control module(88) was also fried. My radio must have been fried as well. All my fuses were good.

You probably killed your alternator as well. They have a rectification circuit, and if you connected the battery backwards, it would short circuit through one or two diodes. As well, your main IGN fusible link is probably gone, those are easy to check with a volt meter... In fact, I'd check all the fusible links.

*edit: on the plus side, your ecm is probably okay. They're made to withstand "stupid mistakes". Pull out the ECM fuse, and probe it for +12v. If you've got it, it's the ECM. If not, fusible link and/or possibly a fuse that burnt where you can't see it... Also used ECMs go really cheap.
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Northstar 87 GT in progress... Engine out, waiting for parts.

[This message has been edited by ryan.hess (edited 04-03-2004).]