I accidentally hooked up my battery backwards and smoke came from the horn rely for 3 seconds, guessing i need to replace relay and hope thats it.
Any comments on that.

 

DOH! This is the 2nd thread I've seen here on this exact same issue within the last year. You do realize that on a top-mount battery, the round terminals are different sizes to (help) prevent this, and on a side-mount battery, the bolt sizes are different to (help) prevent this.

Since you didn't indicate model or year of your car, I'm going to assume its a late 60s/ early 70s Olds. Beyond the horn relay, you've probably also smoked the diodes in the alternator. Pray that your ignition switch was in the OFF position when this occurred, otherwise there may be even more damage. Check the voltage regulator too. If this was done on a late model car w/ ECU..........well, good luck with that.

 

First you need to verify if you lost power inside of the cabin or anywhere else.

 

replace
then
test for inside power and accessories
dont let the DOH guys get you wound up ....
it has happened to most of us at least once that work on rigs enuf....me 45 years of wrenchin..
some times cables are both black and my side posts are the same size ,,,, like my 88 454 motorhome .... flip the master switch off
bought a new quality battery for the engine start ... put new battery in... flip the swittch ,.,,, POW ...wtf ....
well the battery + - posts swapped sides on new the battery I bought ,,,, blew the 2 in line fuse links at the starter
I dont have those on my Pontiacs,,,Olds may., Ive hooked up jumper cables at night + to a red cable to find out it was the ground
replaced by wrong cable ....
hope all will be well we are here for yah!!!

 

I am replacing the horn relay that smoked, hopefully it did not reach the alternator, we will see.
thanks to all for responding, I will update you.

 

You may not have smoked the horn relay, you may have smoked the fusible link or a wire that's hooked to it. Again, do you have power to the inside of the cabin, headlights, etc...

 

I have already replaced horn relay, but no power anywhere.

 

There is a red wire from relay that has a black 1" long wrap around it close to relay.

 

No power "anywhere". With that statement, someone can imply you have no power from the battery? Exactly from where to where do you have power from the positive terminal of the battery? Exactly where does the power from the positive terminal of the battery stop?

 

Yes, that's the fusible link that Eric was referring to. It consists of a smaller gauge wire inside a high temperature jacket. The small wire melts and breaks the connection when there is an electrical overload. There is typically some smoke when the wire melts inside the jacket.

With the battery disconnected, probe the wire beyond the link and put an ohm meter between the probe and the terminal on the horn relay. If you show infinite ohms, replace the fusible link.

 

Coming in late, but yet another example of why replacing parts without troubleshooting first is just a waste of time an money, First, if you even look at a wiring diagram, you will quickly figure out that reversing polarity to the horn relay does exactly NOTHING to the relay. Second, you will also see the fusible link, which has done it's job and blown out. Stop being a "parts replacer" and instead learn about the car so you can make intelligent decisions. It's your time and money you're throwing away.

 

Fusable link still intact.

 

Re-read Post #9 & identify where, in fact, you do have power and begin to trace and measure (w/ a very simple test light is really all you need at this point) exactly where the power no longer flows. This is really very, very simple. DO YOU HAVE POWER COMING FROM THE BATTERY IS A GREAT PLACE TO START.

 

Which fuse would have blown when I hooked up my battery backwards and were is it located.

 

There is no reason to start another thread so I merged this post with the others. There is no fuse, there is a fusible link at the horn relay on the red wire that runs from the power stud to the bulk head connector. You need to get a volt meter and start trouble shooting to see where the voltage drops off. First check the battery because you could have caused internal damage and fried the post connection. From there check the power stud on the horn relay and the back of the alternator. From there go to the fuse box. Again chances are its the fusible link, just because it looks good does not mean it is.

 

Thanks to all that gave opinions and info on my reverse battery hook up problem. All those that thought it may be the fusible link next to horn relay, were correct.
Problem is now fixed and car is running again.
You guys are very helpful, thanks.
neilm