My 97 ford ranger 3.0 would not start. found out it was the battery. I put another one in,hooked up the positive to the negative and the negative to the positive,I know STUPID, my starter relay that is located on the inside of the drivers side fender panel started smoking, I unhooked the cables ASP!Got a new battery and a new starter relay. Now the battery light on the instrument panel stays on.When i pull out # 15 fuse the battery light goes off.This fuse is for the alternator.Is the alernator or the alternator regulator fried? This also blew fuse # 29,audio system fuse ,replaced it ,it is ok now.Befor this happened the battery indicator would stay in the middle, now it stays a quarter of the way above the low marker and the battery light stays on.Is there a more serious problem here than the alternator? Everything in the truck still works , I checked every fuse ,all off them are good.

 

It may not be a bad idea to take the alternator out and have it tested at someplace like Advance, etc. At least it's free.

 

I wondered if you fried your alternator/regulator, and now it is undercharging, causing your gauge to read low, which in turn will make the battery light come on because the truck isnt charging properly. If you have a multi-meter, hook it up, and see what the voltage is. With the battery charged, and the engine running, it should charge at about 13.7-14 volts. If it is like 13.5, that should be close enough. But if its at about 12.5 with the engine running, look at the numbers and note if they stay the same, go up, or go down. If it is at 12.5 and climbing, it may be your new battery just charging by the alternator. If it is at about 12.5 and staying the same, or falling, then i'd worry about your regulator or alternator.

 

Take a look at the fuses in the power distribution box under the hood, there should be a fuse that provides exciter voltage to the voltage regulator. On a 97 Explorer, it's mini fuse 6, yours might be the same.

 

could it be the ecm

 

My bet is that it is the alternator undercharging due to the fact it was fried, or the regulator is fried.

 

Rangercld: I believe that Peter 94 is right on target. And, as 87XLT said, there are more fuses/relays in the power box under the hood that should be adjacent to your battery.

Again, using a vom, you should have battery voltage 12.5 or so, until you start the engine. If the alternator/regulator is working, the voltage should increase at the battery, with the engine running, to somewhere between 13.8 - 14 or 14.2 volts. Take this one step further by turning on your headlights and/or air conditioning while the engine is running. If your regulator is working correctly, the voltage at the battery will be maintained at 13.5 +. If the voltage drops back to battery voltage or less, your regulator is highly suspect.

As Mizzleman said, many auto part places will test these components 4 you with the prayer that it is bad and they can sell you a new one.

I hope that this information helps you.

Russ

 

Most alternators will be a direct short to ground thru the diodes if the battery is put in reversed. Some or all of the diodes will blow.

 

i think you can tell on your own if the alternator is shot. start the truck and disconnect the battery.(dont leave it disconnected for long its not good for it) if the engine does not respond then its probaly charging just fine. but if the engine dies than the alternator is bad. also at night when your head lights are on watch for the lights to get brighter as you increase the rpms. or if you can see the voltage meter drop when you idle. them are some signs of a bad alternator.