Hooked up battery backwards - car won't start

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Towson85

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Stupidly, I was in a hurry to get my car out of storage and accidently hooked up the battery backwards. When I went to start it all I heard was a single click. After realizing what I did, I correctly hooked that battery up. But the car still won't start. Just a single "click" when I turn the key.

The battery is fully charged. I replaced the Starter Relay and the Voltage regulator. Still, just a single "click". All the lights, radio, power top, etc. work.

Somebody mentioned a "fusible link" that I may have blown. Could that be it? Where would that be? I noticed that the "i" wire on the Starter Relay gets hot after I try to start the car.

Help!

thx, pat
 
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Have the battery load tested at a parts store or try another battery if you have access to another. Chuck
 
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Battery fully charged... if lights are inside, you did not notice any fireworks and you hear a click on key on, I'd tend to think that your batt doesn't have the start juice you think it has. Bypassing the solenoid should power the starter if the batt is ok. You can then think about looking at where a fuse blowed.

You could also try to jump start it with another running car if a part store is far away.
 
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Reminds me of a story...laugh of the day....when I was a youngster.

During my high schools days, many many years ago (circa 1980), I was working evenings at a local movie theatre.

After work, I found my mustang car battery dead (yes this same mustang), so I called a buddy and we attempted to boost my car with booster cables.

It was pitch black outside and we inadvertently crossed the cables and hooked up the positive to negative post and vice versa.

We are standing outside watching/waiting for enough power to build up from the boosting car....and the booster cable ends started to glow red...

Then the car started to turn over all by itself....no one was in the car...the ignition keys were in my hands ...as I was standing in front of the car.

We grabbed the booster cables and pulled them off...the booster cable wires had started to melt...

kiss that battery goodby

As I understand it, I was charging the frame, and when the energy built up to a certain level, it started to discharge the energy through the starter....I was told that this reversing of the polarity resulted in my engine turning over in reverse...

A new battery was all that was required, with no long term impacts to my cars electrical system...I got real lucky.

:)
 
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Then the car started to turn over all by itself....no one was in the car.

itsalive.jpg
 

Towson85

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Do you know how to 'jump' the solenoid? I would try that and see if you can get it to crank.
Do you have a multimeter?
Thanks. How do you jump the solenoid? And what should I be testing with the multimeter?
 
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It sounds like your battery is does not have enough amperage to start the car. Try another battery or some jumper cables. You can hook a voltmeter to the battery and it can show 12 volts, but it still may not have enough power to start the car. The other day a similar thing happened to me and under the circumstances I could not believe the battery was dead. My wife, who does not know a starter from an alternator, kept telling me its that battery and I kept looking everywhere else, eventually I relented, and she was right. I have not heard the end of that one...
 

midlife

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Not the fusible link, if you have lights inside the car.
Once you get the car started and running, you should have your charging system checked, as you may have blown the diodes in the alternator.
 
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Thanks. How do you jump the solenoid? And what should I be testing with the multimeter?

Your positive battery cable goes to the starter solenoid. On the opposite side of that solenoide a large cable is connected to the starter.
The solenoid, when 'energized' will complete the circuit between the battery and the starter. THere are two smaller terminals on the solenoid. The one closest to the larger terminal that is connected to the battery will energize the solenoid when power is applied to it.

One method to complete this connection is to use a screwdriver from the battery terminal to the smaller terminal next to it.
Or you can use a piece of wire
Or a remote starter switch

Basically you want to energize the small terminal and see if the engine starts to crank. It won't start (it will sound like it is trying). If the engine cranks then you know the solenoid is good and the problem is the wiring to that smaller terminal. If it doesn't crank then the solenoid is bad or you have a dead battery or a bad starter.

Once you try this I can help with the multimeter tests. There are lots of possible causes/trouble shooting. Too many to type out in a post without more information from above.
 

1973grandeklar

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So did your buddy have to replace his alternator some time later? Hooking up jumpers backward is bad for both vehicles.
If you hooked up your battery backward, the posts are different sizes. The cable themselves on your car might not be making good contact with the battery posts as you may have stretched out the negative cable trying to put it on the larger positive post. You put the negative back on the smaller negative post and the circumference is not making good contact around the terminal. Also make sure the cable and terminal are very clean. As stated by others, the amperage draw for the starter is quite high and the source (battery) is not putting out (whether it is battery itself or connection weak).
 
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71 conv,429cj, 4spd 3.5 N-case, it's not an original but the running gear is correct.

69 Fastback, it's a project.
First thing I check is to make sure battery cables are clean and tight. Then check battery voltage, should be 12.5V at rest. Then turn ignition switch to start and measure voltage, if voltage drops to 10-10.5V check the starter. If it drops below 10V, check the battery. If no voltage drop, then check voltage on the starter cable side of relay, if okay, check at the starter, if okay, pull the starter out.

A couple of things, unless you have an aftermarket starter or a 429 eng, I don’t think you would have a solenoid mounted starter.
The I-terminal wire will get warm when the start circuit is engaged.

One last thing, make sure your ground connections are good. The negative battery cable is grounded to the engine, so the engine needs a good ground to the frame because your relay and voltage regulator both use the inner fender as a ground.

I hope this helps.
Staci
 
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