Messed up something today

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I hook up the battery terminals in opposite direction by mistake today and now car won't startup at all, dashboard light not coming on, none off the electrical working.

I know how stupid I'm for doing this, was rushing to get rid off the car.
 
Any advice what I should do first?

And sorry it is 2004 Nissan Maxima. The only thing come on is security light blinks. I hope I didn't blow the ecu up.
 
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Check fuses?

4 years ago, I replaced chain & sprockets on a motorcycle. I was in a hurry and night was falling. A rear axle spacer fell and I didn't noticed it. I managed to put the wheel back and screw the whole thing in... bending the brake disc. What a mess. 13 years ago, I replaced a front brake system on my motorcycle. As I got interrupted in the process by some phone call or something, I forgot to torque the brake line holder (up the front fork sleeve). The day after, as I was riding, the holder moved toward the wheel, the tire cut the brake line and then I ended up crashing in a car tailgate at a red light (this or I was getting smashed while crossing the road). Two lessons learned: first, never do mechanic in a hurry, second, finish what you started before answering people or phone.

So, back to the question: check fuses?
 
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I would hope the fuseable link or the equivalent failed before the alternator diodes or something even more expensive failed.
 
Check the fuses. Most automotive electrical circuits require some form of reverse battery protection. One form is a diode that only conducts when the voltage is swapped. This diode conduction blows the fuse to save the electronics,
 
There a certain set of dash lights that should light up and blink/glow steady when you put the ignition into RUN (without starting/before starting). If those do not behave as expected, or if this blinking security light is the only response when putting ignition into RUN (before starting), then yes, you broke something that will need to be fixed.

Whether that 'something' is a fuse, several different fuses, a relay, a fusible link, etc. is something you will need to determine before you can move forward obviously. Start from scratch - unhook both battery cables and leave them unhooked for 15 minutes. While they're unhooked, test battery voltage. If it's good, then hook cables back up and turn ignition to RUN. Observe dash lights. Do they behave as expected, or is it still off-nominal? Proceed accordingly...

If you can get your hands on a Haynes/Chilton's manual for that vehicle, it will probably help you diagnose any electrical/ignition issues you might be chasing.
 
To the OP: whatever the problem ultimately turns out to be, please don't forget to come back and update this thread with the details and how you were able to identify it and correct it. I'm sure you will not be the last person to have this sort of thing happen, and when the next person finds themselves in a similar situation, being able to hit upon this thread with any searches and get the relative deets will certainly make their day!
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Yes connecting battery backward will typically just blow the big "battery" or "alternator" fuse, cutting power to the whole electrical system, but no other damage. There should be a box near the battery with the large main fuses. They will be about 80 or 100 amp, and a special kind that aren't found in assorted fuse kits.
 
Originally Posted By: mk378
Yes connecting battery backward will typically just blow the big "battery" or "alternator" fuse, cutting power to the whole electrical system, but no other damage. There should be a box near the battery with the large main fuses. They will be about 80 or 100 amp, and *a special kind that aren't found in assorted fuse kits*.


Seems like those kinds of fuses are suspiciously close to the same size/diameter as various pistol cartridges aren't they? So much so that one might consider using a similar sized pistol cartridge for a temporary fuse in such a scenario, right? What's the worst that could happen...
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Rohan, I would check the fusible links. I sympathize with you. I've goofed up terminals a time or two myself, but fortunately I never had any apparent ill effects from it. Knock on wood.
 
Originally Posted By: The_Nuke
Originally Posted By: mk378
Yes connecting battery backward will typically just blow the big "battery" or "alternator" fuse, cutting power to the whole electrical system, but no other damage. There should be a box near the battery with the large main fuses. They will be about 80 or 100 amp, and *a special kind that aren't found in assorted fuse kits*.


Seems like those kinds of fuses are suspiciously close to the same size/diameter as various pistol cartridges aren't they? So much so that one might consider using a similar sized pistol cartridge for a temporary fuse in such a scenario, right? What's the worst that could happen...
laugh.gif

Maybe smart to use an expended cartridge case rather than a loaded cartridge.
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Originally Posted By: L_Sludger
Originally Posted By: The_Nuke
Originally Posted By: mk378
Yes connecting battery backward will typically just blow the big "battery" or "alternator" fuse, cutting power to the whole electrical system, but no other damage. There should be a box near the battery with the large main fuses. They will be about 80 or 100 amp, and *a special kind that aren't found in assorted fuse kits*.


Seems like those kinds of fuses are suspiciously close to the same size/diameter as various pistol cartridges aren't they? So much so that one might consider using a similar sized pistol cartridge for a temporary fuse in such a scenario, right? What's the worst that could happen...
laugh.gif

Maybe smart to use an expended cartridge case rather than a loaded cartridge.
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48.gif
57.gif



Me thinks there is some wisdom in your words...duly noted!!
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Yep, you'll find a big fuse popped somewhere. I did this on my R1 motorcycle once, and it blew a big 50A inline fuse as well as one or two smaller ones. I feared the same thing you did - that I'd fried the ECU.
 
Originally Posted By: The_Nuke
Originally Posted By: mk378
Yes connecting battery backward will typically just blow the big "battery" or "alternator" fuse, cutting power to the whole electrical system, but no other damage. There should be a box near the battery with the large main fuses. They will be about 80 or 100 amp, and *a special kind that aren't found in assorted fuse kits*.


Seems like those kinds of fuses are suspiciously close to the same size/diameter as various pistol cartridges aren't they? So much so that one might consider using a similar sized pistol cartridge for a temporary fuse in such a scenario, right? What's the worst that could happen...
laugh.gif



No joke I read an AP news article where a guy used a .22 cartridge for a headlight fuse. It overheated and blew, hitting him in the testicles.


EDIT

Ok snopes says it didn't happen but still...
 
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Your not a car dealer or a mechanic. Consequently-here on BITOG you get a FREE PASS! If your were a mechanic or car dealer this thread would be 10 pages long and everyone would be joining hands singing KUMBAYA.....
 
I'm sorry I never reply back to this thread. We fix the issues that night and it was a main fuses on the positive terminal.
 
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