88 B2200 charging system issues.

Here's the deal...got a charging prob with my 88 B. Noticed I was losing power (by that I mean electrical power) while driving. Had the A/C going and the radio. I noticed the speed on the blower fan wasn't blowing as hard as it usually does. Then the radio cut off...almost no electricity!

Tested the bat with a multimeter with truck off...12.2V. Tested it with the A/C off while truck was running...13.4V. As soon as I click the A/C on it drops to 11.6V. Turn the A/C off and it SLOWLY goes back up to 12.8V or so.

I just put a new alternator and battery on the truck. The alternator was a reman from O'riley. Took the alternator off and took it back in today to have it checked...guy said it's good.

Looked at the belt...it's cracked and SLICK. Got new belts and the parts guy said to put the alternator back on with the new belts and if it still does the same thing they'll give me a new alternator. He said they can only test the alternator "free spinning"...not with a load on it.

I also changed the connector on the back of the alternator...the one with the two wires that's near the bottom of the alternator. The connector was corroded...so I figured that might be an issue.

I drive home in the dark...so this issue is a real problem.

What do you guys think? Am I heading in the right direction?

The bad connection/connector can readily be the issue. So take care of that. Battery voltage should be higher than that with AC on, shouldn't be at a discharge voltage. ALWAYS fix first what you KNOW is bad !!!

What do you mean driving back in the dark? Even if just running off the battery, should've had lights.

It takes me 45 min to get home from work. I work until 10:00 pm. The lights are mighty dim by the time I get home.

I was expecting high 13's or 14V with the truck running and the A/C on. New belts, new connector and a wire brush on the bat terminals & connectors. Im trying to eliminate simple stuff...to find the issue. Could be a series of small things or one big thing...like the alternator. Maybe it's weak and cant handle a load. I tried the screwdriver test to see if the alternator was good...it didn't stick very well...so I'm suspicious. I'll put the new parts on tonight when I get home and post back tomorrow with the results.

Thanks for the help, by the way, cusser.

Is your battery relocated or in the stock location?

It's in the stock location.

my truck runs at roughly 13.5 with the fan on 4 and the a/c on.
if i turn the lights on it gets down to low 13's to high 12's.
i dont know if this is helpful or if its even normal, just thought id throw it out there.


edit: and unless im really blasting my stereo, it doesnt affect the voltage at all.

Good to know. At least I have a baseline of some sort. If this doesn't work I'm giving some thought to doing the Cobra alternator upgrade. I like the fact that the Mazda has GREAT headlights. They're better than my 2012 Dodge Challenger for driving at night. I drive home at night 5 days a week through deer country...so good headlights are important! Thanks again!

I suppose that you've already made sure your grounds are clean and tight since you changed the battery recently?

I have a similar issue... i swapped to a ford 3.8 alt and it will work fine for a few days then just stop charging ... i pull it out ..take it to the test bench and test it several times ... always test out at 14.9 v....so strong... starting to think maybe its the heat ...but u would think it would be right away....all thats changed in the last few months is i powdercoated the alt ousing on the outside... looks dope and works good for a few days then boom no chargy... i have a spare harness for a extra cab... I am yarding my dash replacing all harness's installing a/c and hoping on the other side the bitch will work....for more than two days...

Yep...checked the grounds.