Hypothetically speaking of course. Let's say I have a friend who has owned a Fiero as long as he can remember and he bought a new battery for it and never knew European batteries have the positive and negative terminals switched (so positive on the right side and negative on the left side) and might have accidentally hooked the battery up with the polarity reversed?

Okay, okay, that was actually me.

Seriously, I never knew European batteries have the terminals switched. My old battery wouldn't charge anymore (I guess one too many deep discharges) so I bought a new one yesterday. I first tried to connect the negative cable (I know you should connect positive first but I was only testing if the cable could reach the terminal) and for some reason it wouldn't fit over the terminal. I then briefly connected the positive cable and it was actually a bit too big. Only then did I realize the terminals were switched. And even though I didn't have the positive cable connected, I'm not sure it wasn't touching the terminal when I connected the negative cable.

My old battery still has a little power in it and when I turn the key, everything comes on that should come on and it tries to turn the starter but I have no idea if perhaps my ECM is fried (on the other hand, if the fuel pump comes on, the ECM is still intact, right?).

So could I have fried anything? And if so, what?

(no, I don't have a new battery yet so I can't test if everything is still working)

iv done that before...
i cant remember what happened tho. it was along time ago.
i didnt think anything happened. it didnt want to do anything when itryed starting.
i know iv had a screw drive placed on the battery one time and the screwdrive rolled and toched both terminals and sparks were flying and melted the terminals

One would hope (although I don't know for sure) that the ECM and instrument panel circuits have a some sort of reverse polarity diode protection on them since it's a lot of protection for only a few cents during manufacture.
Everything else that I can think of is pretty much neutral as to which way the current is flowing so it shouldn't make any difference.

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Dave

www.ltlfrari.com

The only circuits that could possibly be affected are the ones that are hot at all times. I've grouped all the items that are hot at all times below in three groups, namely circuits with relays, circuits with switches, and circuits that have neither. All of the items in groups 1 and 2 are protected since you would've had to activate the relay or flip the switch to have power flow through the circuit beyond the switch or relay. The items in group 3 are the ones of only concern... of course they are among the most expensive parts to replace if they're damaged. The alternator is safe because the only wire hot at all times is the one leading to the battery for charging, and nothing is going on in the alternator without the engine running. So effectively it's protected by the ignition switch. I can't tell you for sure about the ECM or radio, but simply starting the car up will probably give you your answers. At least you needn't concern yourself with anything but the proper functioning of the ECM and radio (clock and memory function only).

GROUP 1:
Headlight actuator relays;
Coolant fan relay;
Fuel pump relay;
A/C power relay;
Door locks relay;
Defogger timer relay;
Horn relay;

GROUP 2:
Cold start injector and switch;
Hazard flasher;
Audio alarm;
Ctsy lights;
Power trunk;

GROUP 3:
Alternator;
ECM;
Radio.

The alternator would not like that. It most likely messed up the rectifier. But usually when stuff like that go, it is accompanied by smoke.

Welcome to the human race
Most likely all is well if you did not turn the key.
Check fuses, but I don't think any blew, and proceed with life

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Red 1988 GT 5 speed
Poly all around, Koni's & Lowered
LQ1 powered

I don't think you would hurt anything. All the diodes in the system would be reversed biased and should not flow any current. Even the ECM power input is diode protected so that a reverse polarization should not hurt it..

I think you will be fine.

[This message has been edited by Dodgerunner (edited 10-23-2009).]

I know the radio is still working, and the ECM is working as well since the fuel pump comes on when I turn the key. So I guess I'm fine then. Phew.

I returned the battery yesterday and they looked up which battery I need for the Fiero. They had to special order it from their supplier and I got a call this morning they received the battery (yeah, that was crazy fast). So we unpacked it and... sure enough it was exactly like the original Fiero battery with the screw-in type side terminals (we use the cylinder shaped top mount terminals in Europe). And of course, not a single store here has those US type cable terminals so now I either have to return this battery as well, or order something like this.

This type is common over here..

quote Originally posted by Cliff Pennock: I returned the battery yesterday and they looked up which battery I need for the Fiero. They had to special order it from their supplier and I got a call this morning they received the battery (yeah, that was crazy fast).

Grrrr. things like this annoy me. It's bad enough we have thousands of languages and difficulty communicating as a world culture but then we add to it and can't standardize something as simple as "+" on the left and "-" on the right. I hope everything works out, I have to make sure I check all my new batteries first before hooking them up.

I have seen battery terminals reversed many times and it will almost always burn out the bridge rectifier used in an alternator. So just keep that in mind.

Looked at the electrical drawings and Liteblub..... is correct.

In the Fiero reversing the battery puts battery power directly through the diode bridge of the alternator. Very much of a contact and it could easily blow the bridge. The only protection is the fuseable link E by the battery, but the diodes would go long before it would pop.

Hopefully you didn't touch them both...

Good luck..

[This message has been edited by Dodgerunner (edited 10-23-2009).]

Hmmmm.

Is there any way to test (without starting the car) if I destroyed the alternator?

Does your local auto part store do bench testing?

quote Originally posted by Cliff Pennock: Hmmmm. Is there any way to test (without starting the car) if I destroyed the alternator?

You could remove it and have it tested. Most auto parts places can test an alternator.
You might be able to remove the belt and spin the pulley with a drill then measure the output while it is still on the car. If I recall you need to spin it around 1000+ rpm.

If I read your post correctly and if you did not have both terminals connected to the battery at the same time you are o.k. Both connections have to be made for current to flow in the circuit from the battery. Basic Electronics 101.

quote Originally posted by wolfwolf: If I read your post correctly and if you did not have both terminals connected to the battery at the same time you are o.k. Both connections have to be made for current to flow in the circuit from the battery. Basic Electronics 101.

By the sounds of it, he isn't sure if they were both touching at the same time, but there's a good chance they were

[This message has been edited by LitebulbwithaFiero (edited 10-24-2009).]

Guess the question is did he see or hear any sparks or arcing. Since it would have been a dead short though the diodes there should have been a good pop if a connection was made.

You could test the alt somewhat with a test light and a 6V or greater battery. Remove the primary alt. wire from the stud. Connect the battery and light in series and then touch the remaining two connections to the large stud of the Alt and the frame. Then reverse the connections and try.
One way they should light the test lamp the other way it should not if the diodes are good.
If it does not light the lamp either way or lights both ways then that might be a good indication that the diodes are compromised.
Not a 100% check but better than nothing.

[This message has been edited by Dodgerunner (edited 10-24-2009).]

quote Originally posted by jscott1: Grrrr. things like this annoy me. It's bad enough we have thousands of languages and difficulty communicating as a world culture but then we add to it and can't standardize something as simple as "+" on the left and "-" on the right.

Thank you. The manufacturers of this stuff must talk from time to time. I've never understood why things like this can't be standardized. For the most part, we've all agreed world wide to use 12V DC right? Why not go the next step.

Hope all is OK Cliff. Don't feel too bad....we've all been there in one way or another.

Motors doesn't care.
Wiper delay if it left on.

ECM and Alt main one...
Alt test at auto store/shop.
If ECM still work, you got lucky. ECM get two power circuit... One from Ignition switch. One from RAM backup. RAM backup always on But! maybe Revere Battery protected. (Ignition switch is Not protected as I can see.)

Some relay Maybe blew up but not likely. Diode Protected Relay but diode rate is high than 12v. Depend on relay and if it turn on.
Dash gauge/speedo and Cruise if ignition switch it turn on.


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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top of every forum page...)

[This message has been edited by theogre (edited 10-24-2009).]

Ok I finally got the new battery in and the car started right up so I guess the ECM is fine. However, I'm no longer sure my old battery was actually the problem. Let me explain.

When I wanted to start the car last week after it had been sitting still for about a month, the battery was dead. So I took it out and charged it at home (my car is parked in a public parking garage about a 10 minutes walk away from where I live). When I put it back in my car, the car started with no problems and I drove the car to the garage to have the axle and the tie-rod replaced. The garage is only a two minute drive. When I picked the car up the next day and I started it, I noticed the battery was very weak. In fact, the next day it wouldn't even start. So I took the battery out and charged it again. The next day it started fine again and I made a 30 minute trip. Later that evening when I wanted to start the car again, the battery was dead. I started it using jumper cables and drove home.

One thing I noticed however (on both trips from and to home), was that my voltage gauge was reading a much higher voltage than usual (not sure how much but I guess between 15 and 16 volts). I thought that was caused by the fact the battery wasn't charging. But when I hooked up the new battery today and started the car, I saw the same thing - high voltage. I have no idea how high it really was since I didn't bring my voltmeter (will do so tomorrow).

Anyway, I hope the regulator of the alternator (a CS130) isn't destroyed. I really, really don't want to have to remove the alternator...

I really think the only thing you would damage is the alternator. Ive charged up a battery before with wrong connections. I just drained the battery back down and charged it back up correctly and it was fine. Alternator was not. A bad alternator will also kill a battery pretty quick too. Sounds like that was bad in the first place on yours.

Let us know what the voltmeter readings are when the car is sitting, and again when running. Hopefully it will be around 12.4 and 14.4 respectively.

------------------

1984 Fiero SE

Does kind of sound like you already have a diode problem with you Alt. It's funny I just was reading an artical that said the CS alternators have different diodes that don't have as long of life asn the old SI Alt.
If you have a volt meter set it on ac volts and see what the Alt. output reads on the large stud to the frame. If you getting more than 1 V AC you could very well have a bad or leaking diode. About 1 volt ac or less is fairly normal output.
If a diode short it can take a battery down fairly fast. They can also just get leaky but still drain a battery.

If you have a bad regulator in the altenator charging in excess of 16 volts it will fry the in sides of your new battery. To be sure check it with a volt meter, don't trust the Fiero's volt meter for a good reading. Turn it off and fix the altenator if this is the case.

I had a 1973 911T that had two 6 volt batteries up front , one sorta behind each headlight. I kept smelling battery acid. When I checked voltage It was running at 18 volts. It was the same regulaltor as my VW van had.

I can't find the actual reference right now, but I was reading somewhere in the service manual last week where the ECM will shut down if it detects less than 9 volts (I think) and more than 17 volts. That seems like a neat protection idea for a faulty regulator.

same thing hapen to me a year or so in my 87 gt. i relocated the batery to rear comparment and accidentaly switch the cables and the ECM just bleww...

replace the ECM and the car just start fine.

Something else might be draining your battery, too.
First thing... listen for the fuel pump.
Second thing... listen for the headlight motors or relays clicking.

Either one can kill a battery rather quickly.

Make sure that your trunk light switch is working. Push up on the little black switch in the latch assembly. The light should go out.

If all of those tests show nothing, then you can unhook one of the battery cables and place an ammeter in series to measure current drain.
If there is a significant drain, start by unhooking the alternator hot lead. (Be careful not to ground anything.)
If that doesn't help, start unplugging fuses until you find the one that makes the current drain go away.

quote Originally posted by RWDPLZ: Let us know what the voltmeter readings are when the car is sitting, and again when running. Hopefully it will be around 12.4 and 14.4 respectively.

Actually, it was 12.38V and 14.75V.

So yeah, I guess everything's working as it should. Phew.