Hi guys.

My battery isn't charging. I assumed it was the alternator but I pulled it and had it tested. It tested fine. Just to be on the safe side I bought a new alternator anyways.

I installed the new alternator and it doesn't seem to be working.

I'm testing at the battery and get 12.5v with the truck off. I turn the truck on expecting 14.5v, but it stays right around 12.5.

This is a 1990 Hilux, 22re 4cyl., the voltage regulator is in the alternator (i think) so that shouldn't be the problem.

I started to check all the basic connections and they look good. So I don't know. Thats why I'm here.

Any help please?

 

Why do you think the alternator is not charging? Did it kill a battery?

:wabbit2:

 

I followed the harness from the alternator, which came to a 5 wire plug under the airbox. I tested all 5 wires with the multimeter and couldnt get anything over 12.5 volts.

 

The alternator is probably working right, but not charging the battery.


2 reasons. first the multimeter stays at 12.5v with the truck on and off. My understanding is it should go to 14.5v with the truck running.

2nd reason. if I disconnect the negative while the truck is running it will die out. It should stay running if the alternator was doing its job.

 

Why are you messing with the battery and starter to begin with? Most folks just don't test their stuff with a multimeter for the heck of it.

:wabbit2:

 

alternator cannot be possibly working right if your getting only 12.5v with the engine running. Either your alternator is bad (internal voltage regulator) or your field??? (or is it stator I forget lol.) winding wire is bad. (the 10 mm nut bolted on cable). Take alternator out of truck, take to autozone or one of your local parts places to have it tested. If it tests out, problem is in the wiring. Multimeter will not tell you whether your alt is bad or your wiring unless you have a jig made up to run the alternator outside of the vehicles wiring.

 

Buying aftermarket you'll get 4 bad ones to 1 good one and they will all "test" good.

:wabbit2:

 

I was out wheeling and it wouldn't start, (click, click). Like a dead battery. Put a jumper on it and it started right up. So this is why I think its the alternator. Small chance its the starter, but I don't think so.

Alternator should be good. Its brand new. I had the old one tested and it tested Good.

The ground to the frame looks good and is tight also.

 

I would be hating it, if that happened.

 

I've gone through 2 autozone alternators. On my third one. First one went in less then a week. I like my mud, with mud/water they go fast. Luckily this last one has been taking some abuse.

And wabbit is right. Sometimes they test good. Why? Because they may be putting out like 13.8 volts or some crap like that on their machine which isn't enough to fail, but as soon as you put it in the truck with longer cables/wires etc etc, the regulator cannot hold voltage.

 

Guy at the autoparts store was saying maybe the ignition, like the ignition is not telling the alternator to turn on.

This was a few hrs before the battery stopped charging.

 

see my above comment. cannot comment on the ignition being the issue, I'd have to look at a wiring diagram, but I wanna say the ign switch or otherwise is not tied into the alternator. Is your battery/brake light on?

 

http://www.alternatorparts.com/under...lternators.htm

 

see above comment, is your charge and brake lights on on the dash?

 

No lights are on.

I wont be out there messing with this for a few more hrs. Its too hot outside.

Sucks I figured this to be an hr, long job. I aint got time really to fix crap right now and I want to go out this weekend. I might just have to run it and hope it works?... PpPpp.

 

if no lights are on then it's not the stator/field wiring/ignition. If it were those or the CHG fuse in the fuse box under the hood, that light would be on as it indicates the field windings aren't getting power. So your problem lies in the battery cables/grounds themselves or inside the alternator in the way of the voltage regulator or stator brushes. Which matches up with the fact you were in a water/mud pit before it went out. I hate auto parts counter people. They have no working knowledge of anything.

 

Ok I went and got a new alternator and it still dont work.

I put it back in the truck and when I test the main + off the alternator. I only get 1.5. It should be 14.5.

Something must no be telling the regulator to work.

Any ideas.? Im gonna go look for more fuses all I found so far was the ones under the hood.

 

Do you have a battery load tester. I have seen batteries that appear to have voltage but have a broken cell and do not work under load. With a broken cell your alternator will not have a complete circuit. Try the load tester on the battery if it fails replace the battery.

 

OMg, it was a fuse inside the cab. The actual fuse is good but its loose and is making a bad connection.

So... PROBLEM FIXED!

 

Im having almost the exact same issue. The only difference is my battery gets charge intermittently. And on the rare occasion my break light/battery light flicker. I replaced the alternator a few months back when i blew the previous one in a mud puddle, and I just replaced that one with a warrantied one on the weekend. The most recent replacement made the issue worse.

Can I ask what fuse it was? Im going to take a look after work. Itll be a huge relief if it was something that simple.