I was out driving my 4Runner, stopped at a gas station, turned the engine off, took the keys out of the ignition. When I put the keys back in, and turned, I noticed a spark (also heard it) and all my electrical completely died. Could not turn the engine, no lights, all dead. I noticed the negative battery clamp was a little lose on the terminal, wiggled it a little bit, and everything came back to life. Im assuming thats a problem (would a lose clamp cause a spark like that?). I dont see any fuses blown.

Can I just replace the negative battery clamp? Its in bad shape and is normally a little lose. Id like to buy a new clamp and just attach it to the existing cable. Ive read some posts where people suggested replaing the *whole* wire (because of internal corrosion), which I really don't want to do. I appreciate any suggestions!

 

Did you check ALL of your fuses? Is your battery grounded to the body? Check all connections on your ground wire. Corrosion is a real problem.
"Usually a little loose"? Poor grounding makes for electrical hazards....causes fires in houses. It's not good for your truck, either. Always keep your cables clean and tight. Replace the clamp for sure. Peel back a bit of the coating at the tip of your wire to see if the corrosion has traveled. If it has, there's no telling how far unless you strip some cable jacket down the line and have a look. You can coat your test strip with rubber electrical coat and good elect. tape if it looks good. If not, replace the cable.
Oh! Check for any burned terminals on your starter and alternator...melted wire jackets and such.

 

A loose cable could make a spark because there is an electrical connection being broken. You could just put a new terminal on it, but check for corrosion on the wire. It might be best just to buy a new wire. You should fix it soon. Batteries create hydrogen gas when they charge and a spark can make them explode. I have seen one explode before and it makes quite a mess.

 

Thanks for the replies. Ive checked all the fuses I can find (according to the Toyota FSM) and I dont see any blown. I did peel back the wire jacket, and it has corroded down pretty far. Im just gonna replace the whole wire. Thanks for the info.

 

Good deal!
For good measure, check your battery fluid level and clean your posts real good. You ought to clean 'em regular like.
Have fun!