First off I have a 1996 Ford Ranger 4.0 4x4 auto XLT Crew Cab
What my problem is the battery light is on and when I take the battery terminals off the truck stays running and the light go's out.But when I reconnect them the light comes back on and seems to be running off the battery. Also if I don't start it every couple of days the battery goes dead Any and all help would be greatly appreciated THANKS

 

Battery light usually (indirectly) means an alternator or charging issue. Check for adequate charging voltage at the terminals around 2500 RPM with lights and accessories on, while under load.

Probably have a couple things going on. The battery going dead may be an indication of a parasitic or "phantom" load on the battery, sort of like a light left on, but different in that it isn't obvious. It's also possible the battery is worn out or defective and will no longer hold a charge. YouTube has some decent DIY video instruction on troubleshooting a parasitic draw if this is part of the problem.

In situations like this it's important to find the source of the trouble for certain, because a defective battery can damage a good alternator, and a defective alternator can damage a good battery. Have both battery and alternator tested if necessary, use your best judgment on the battery, even if it tests OK a five year old battery is probably in many cases suspect. Cables and grounds at engine block and firewall are important and often overlooked.

 

It doesn't matter how many old geezer "experts" say that it is okay to do so. NEVER take the battery cables off of the battery while the vehicle is running. First, the spark could blow the battery up in your face. Second, the vehicle is meant to run off of the battery voltage, not what the alternator is trying to output. It's an easy way to ruin an alternator, even though your vehicle might already have an alternator problem.

Find if your vehicle has a good battery or if your vehicle has a parasitic draw.

 

I will look into the Parasitic draw the battery and alternator are new and were both tested as good

 

Damn good point. Reinstalling might even be worse as far as that goes.

No, actually the battery's only purpose is to start the truck. It does however act as a kind of filter, absorbing voltage spikes, but it is the alternator that provides all of the current for ignition and lights and accessories. Yanking a battery cable from a terminal probably won't hurt the alternator but it will send a huge voltage spike through the electrical system, possibly damaging more sensitive components like ECUs and other electronic gee gaws common in more modern trucks.