Battery terminals reversed...HELP!

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Mike Corn

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Location
Kennesaw, GA
First of all let me say that I am a freakin idoit... My battery is 6 years old on my 05 trac so I replaced it with one from Interstate Battery. Being 98 degrees today and burning my hand and squinting my eyes, I put in the new battery not really looking at the terminals. I immediatly saw it smoking the wires. So I thought, ok I forgot to do the positive first and the negative last as is commonplace. Smoke again, only this time I could not really jimmy the cable loose as it was screwed just tight enough to make it quite hard to jimmy loose.



Enough excuses, I am an idiot.



So I put the battery in right, started the car and noticed 1) My radio was blown and 2) the charging system light (Battery Pic) on my dash was illuminated. Now I say oh sh**.



I looked up the radio fuses and noticed that the 20amp fuse was burnt. No problem easy fix.

Upon reasearching what could cause the light on the dash, it seems that this reversed polarization has many differences in opinions on what can happen.

1 is that alternator can be blown, however some people say that modern cars have dumba** proofs to prevent real hard damage to the electrical system.





I took my trac to advance and the diagnostic testing revealed that after each crank, my battery volts were decreasing and 2 the little testing thingy could not get stats from the alternator. The tech there said it may be so low (IE Bad) that it cannot read anything.



I have an extended warranty through ford. My dealer will take a look and if it is compatitble with the warranty (Should be) they will not charge the 98 dollar diagnostic fee and replace the alternator. My worry is that they will be able to detect the black spots on the battery cables that some jack monkey reversed the polarity of the battery...





Please help!!! If anybody could help with insight into this issue would be greatly appreciated. Any experts near Atlanta? I could also use help with figuring out how to remove the alternator so I can take it to advance for more testing....
 
Mike C,

I have never experienced anyone doing this before, so this is just my guess....



You probably fried the alternator...which is very common when hooking up jumper cables backwards.



You already know that you fried the radio...and that may include anything else electronic..to include the computer and perhaps ingnition electronics???



Other things that could be effected might be some of the sensors, dashboard, and perhaps things like door locks, security systems and even the lighting control modules.



I don't know if Ford has any protected circuits to blow a master fuse incase the battery is hooked up wrong...but I would pray that they do or you may be in for a lot of expensive repairs.



Perhaps l1tech will jump in and let us know more about what might be damaged.



....Rich
 
All other electronics seem to be working, power locks windows, all lights, except the rear, fuel gauge, odometer, all dash lights and readings, compass, thermometer, and auto dim mirror.
 
Mike,

You many have gotten very lucky and Ford may have some sort of reverse polarity protection to prevent major damage if the battery terminals are reversed.



I suspect that you blew out something in the alternator...probably a diode, or possibly the voltage regulator. Either can easily be replaced.



The smoking may have damaged the insulation on your battery terminals, or even on some other wiring. I would check out all exposed wiring to insure you have not melted any insulation. If the wires short out, it should just blow a fuse, but the main battery, alternator and starter wiring is not protected by fuses, and could cause a fire....so check them out carefully.



Anyway, It sounds like you may have dodge a big bullet..:grin:



...Rich
 
Last edited by a moderator:
Any idea how to check the diodes, or voltage regulators? I am not very familar with car mechanics besides basic stuff. I really have no idea about electrical systems.
 
Any idea how to check the diodes, or voltage regulators
Click to expand...



Remove the altenator and take it to parts store. They should have a way to bench test it.

Disconect the battery. One plug and one terminal the belt and two bolts. Easy to remove.
 
Mike,

Eddie is right, just take it off and take it to someplace like AutoZone and they will bench test it for you and can tell you what parts it needs, or if it's better to just buy a rebuilt unit which might be your best bet since you said you are not into the nut & bolt mechanics.



...Rich
 
I wonder what would have happened if you tried to start the truck with the battery connected backwards...Things that make you say hmmmmm
 
There may be a fusible link in the harness between the alternator and battery. Anyone with a wiring diagram that can confirm?



If that's the case, your alternator may be fine.
 
If fusible link should it just be in one of the connectors from the Alternator to the battery? Yes a diagram would be great.



Common Bo, please don't post if your going to say what I already did, an idiot move, yes I realize that it could be bad!!!



Does anyone think FORD will replace it if it is bad from the extended bumper to bumper warranty?
 
Any one have any tricks to loosen my tensioner pulley? I dont have any clearance from the bolt to the fan... The fan is in my way. I dont think I can take it off without ripping out t he radiator which will require removal of the silver metal lines (Coolant Lines I think)...
 
Mike,

Fusable links look just like a regular wire that is designed to blow like a fuse. Some have a molded tag or special looking connectors.



As for Ford fixing the problem, be it a fusable link or alternator under your warranty???...probably, if you don't tell them what you did? A blown fusable link would be suspicious and the might search for a short and suspect that someone crossed wires somewhere? A blown alternator contains electronic components that can fail without warning and typically do not show any obvious damage. I don't think the computer is capable of recording anything if the battery terminals are crossed or shorted?



Many years ago I owned a new Camaro. A friend at work need a jump start and connected jumper cables to my battery and while the engine was running he deliberately touched the other ends of the jumper cables together to insure he got a spark :angry:



We got his car started but my battery charging light came the next time I started my car. I took it to the dealer and just told them that the charging light came on and they ended up changing the alternator..under warranty, and no questions asked :grin:



...Rich
 
I cannot seem to find a pic of the fusible link. I think all electronic connectors going to the alternator do not seem to have burn marks on the alternator...



I am about to take the alternator to auto zone.



The positive battery wires did smoke really bad and have black spots on them. The connector between both battery terminals connect into some other electronic connector near the 4x2 black cylinder, near the master cylinder. Both of those look unburnt as well.
 
Thanks guys, bad alternator. I brought my truck up to the dealer and hopefully they will fix it under warranty.



Special Thanks to Richard, Good looking out!



Thats what I love about this forum, a great place for a wealth of knowledge...



I hope I did not blow my main computer, but I think that would have broke most of my electronics.
 
Why should ford fix 'under warranty' something that you broke? The fried wires and new battery are going to be a big clue. You don't have to tell them what you did but if they ask, you should be up front with them.
 
will e,

If they see signs that they know were caused by someone crossing wires or battery terminals, they probably won't ask him what happened...they just won't fix it under warranty. A short in the alternator could damage wires and would be the suspected cause.



...Rich
 
Will, Because I paid like 4 thousand dollars on top of my 12.5K used Sport trac for a certified pre-owned bumper to bumper coverage. This is suppose to fix anything non maintenance related.



So If my son pulled on the door lock and broke it, best believe I will take it in to get my money's worth.
 
Mike,

So you think that the warranty should include fixing this? Maybe I misunderstood. If they tell you that it was taken out when someone connected the battery wrong and that this isn't included under warranty would you feel like you were unfairly treated?



Let's say someone forces the window down to break into your car and messes up the regulator, would you think that should be covered?



 

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