So I just changed my spark plugs out for some new ones yesterday. I was a big dummy and cross-threaded two of them, but it was just the plugs because the old ones went back in fine. I took it for a drive and it seemed fine, nothing new or unusual.

Today I got more plugs to replace the ones I messed up, installed them just fine this time. I fire it up afterwards and my battery light on my dash is suddenly on. I went and looked over all the wires around the alternator, battery, and that junction near the fender where the alternator and battery meet up with some other odd wires all of which seem fine.

The alternator seems to be giving off a good strong charge, based on the voltage on the dash. It turns over strong, so I don't think that the battery is really weak (it was also replaced within the last couple of years). What could cause the battery light to come on when everything seems to be operating fine?

I think the engine sounds like its running better with these new plugs. I'm just concerned about taking it for a drive if there is going to be a problem with the battery somehow.

 

Toss a meter on the battery when the engine's running. 14v> is good. If not, put the red lead on the alt output. Should be 14v or close. Don't rely on dash readings unless you have a true volt guage. Even then, check at the alt and battery.

 

Well of course the battery in my multimeter was dead, and of course it was a type I didn't have any of.

I checked the battery charge with the truck off, it was 12.35 about. Then with it running using the battery terminals it was reading 15.06 V. Where should I be testing the alternator? The only lead that I could find went to the junction on the fender which leads right to the battery, the junction also read 15.06 V.

 

Black lead to ground, red lead to the terminal at the rear of the alt. (Main connection.) But, seeings that the readings look good at the places you checked, my next idea would be to load-test the battery...and check all connections. I know, shot in the dark, but, I'm going through the motions I would try...

 

What's the theory on the charge light anyway. If it NEEDS to see something over 12 point something volts or it comes on.(?)

My first thought is what got wiggled loose when you changed the plugs but I'm sure you thought of that.

With my luck lately, it would happen all by itself and have NOthing to do with changing the plugs.

If you've got more voltage running than you do NOT running, the farmer fixer say's it's prob ok.

I wonder if the regulator freaks out and shows the charge light if it's low OR higher than it should be.

Wait! I know

Most autoparts stores will check charging systems and a few other things for FREE.

They come out with a real cool meter hoping to sell you parts.

 

Well it warmed up a bit today - it was like 8* yesterday, and 25* - and I decided to give it another go.

I started it up and the light was still on, I rolled my eyes thinking about when I will get a chance to take it in to get inspected and the cost of the new battery I would be buying... but when I looked down to turn off the engine the light had gone off. I watched it for a bit and it flickered on for a second then went out. I tapped the throttle and it seemed to come on in response to that. I did it again and it was a shorter flicker, the third time I tapped on the gas it didn't come on at all. The temps are supposed to stay in the single-digits for high's here this week. Thankfully this isn't my DD, but I'll be able to check it a few times when its cold to see if the light returns.

The battery has a stamp out thing with (Jan) and (9) blacked out. Since I know it was replaced in the last two years I'm pretty sure the battery is from Jan 2009. I have always had good luck with batteries here in MN, so I personally think it is strange to have these problems with such a new battery. What do you think: is my "new" battery just bad in the cold, maybe I should expect these kinds of problems in this environment after such a period of time?

Thanks for all the input guys!

 

i think the volt regulator is in the alternator.

Try blasting the back of the alt with a hairdryer to heat it up and see if that changes anythinig.

or almost any autoparts store is happy to check them out, IN the vehicle, for free.

 

Batteries always have a rough time dealing with the cold.

 

I had the battery light come on and flicker, but I was getting a good reading on the battery. It was a ground problem. Check to see if you broke or took off the ground wire on the right side of the motor going to the upper intake. My problem was I left that ground wire unhooked and caused my battery light to come on. If that is good check all the grounds you can get to.