How To: Diagnose Charging and Battery Issues

[My5ABaby]

The proper way to do it is via the FSM. However, the below method is quick and dirty.

The DMM (Digital Multimeter Method)
1. Turn on the engine, headlights, heater, and fan on high.
2. Test the alternator output by measuring the voltage between the alternator positive post and the alternator frame (13.5 to 14.4 volts).
3. Test the primary battery positive (+) wire by measuring voltage between the positive battery terminal and positive alternator post (0 volts).
4. Test the primary battery ground (-) wire by measuring voltage between the alternator frame and negative battery terminal (0 volts).
5. Turn off the engine, but leave the lights on.
6. Test the battery by measuring the voltage between the two battery terminals (~12.5 volts).

[FC Zach]

This just may help. Im havin charging issues, on my third alternator! My batterys good and the terminals are good as well, just cant figure it out. The reman alternators im getting work fine for a while then my voltage drops till the battery dies. Def a head scratcher, im not sure if its the RPMs damaging the aternators (if thats possible) or if there is a wiring problem. Its so agravating that I've decided to try an FD alternator. Anyone else had any trouble with reman alternators besides me?

[Polito Racing]

^nope.

[RETed]

I wouldn't touch anything except from the Mazda dealer.
Almost all the big chain auto parts stores SUCK.
It's not even worth their "lifetime warranty" if you have to keep going back to replace them!
It's the same story with starters.


-Ted

[classicauto]

This just may help. Im havin charging issues, on my third alternator! My batterys good and the terminals are good as well, just cant figure it out. The reman alternators im getting work fine for a while then my voltage drops till the battery dies. Def a head scratcher, im not sure if its the RPMs damaging the aternators (if thats possible) or if there is a wiring problem. Its so agravating that I've decided to try an FD alternator. Anyone else had any trouble with reman alternators besides me?

Sometimes there can be issues with reman's as REted has suggested.

However, many AFMKT's offer new and reman'd starters/alternators. The difference being one is made from a core that you give them when you buy yours, while the other is an entirely brand new unit. I'm running a new FD unit purchased through Carquest which has done me well so far.

I've seen my fair share of horror stories believe me, and it may be the fact that I buy so much paint from these guys that I know I can wring some necks if the parts go south, but I have great confidence in the new starters/alts made by major manufacturers. But Ted's definetly giving good advice.

[FC Zach]

Yeah I work at Advance for a second job and will agree that the remans' lifetime warranty isn't worth the hassle. I'm on my second starter and 3rd alternator. Hell even the new products are a gamble, I went through three water pumps before I found one that didn't leak, which pissed me off because I took the time to paint each of them , , , BASTARD PARTS! !

[djmtsu]

I wouldn't touch anything except from the Mazda dealer.
Almost all the big chain auto parts stores SUCK.
It's not even worth their "lifetime warranty" if you have to keep going back to replace them!
It's the same story with starters.


-Ted

Not 100% accurate.

Autolite, Worldwide, Palladium, Duralast. All crap.

Beck/Arnley= WIN.

I am getting Zach an FD alternator for his FC. Some on the shelf, although listed as 100 amp, are higher. Up to 110 amps on the spec sheets. Our defective return percentage on rotating electric is lower than 2%.

[My5ABaby]

I've gone through 3 Autozone/Advance/whatever (don't remember) alternators. The first one just stopped putting out enough, the second failed somehow and started putting out voltage based upon rpm (higher rpm = more voltage... over 16), and the third just stopped putting out enough again. Thus far, the one in there, another warranty one, is doing well.

[FC Zach]

It wasn't the alternators the whole time, I didn't have the voltage regulator plug attached. Hell,, I didn't even have the plug since I've cut the harness after converting to carberation. So the new question is, , , Is the color of the wires BW & BrY for my S4. And also since I've already bought a new FD alternator where do these wires go (if these are the correct pair) on the FD alternator? I've read an archive on the other forum (probably shouldn't mention that) that said the Black/White wire goes on the upper plug of the FD alternator, is this true. And last can can someone send me a link to the website that makes the Dual Sheave Conversion Pully for the FD alternator?

[FC Zach]

Yeah I know, I'm a needy M'er F'er. The Black/White is a ground that i traced going to the ECU. Well since I no longer have an ECU, can I just ground the wire to the frame? Or is this some kind of switched ground that I need the ECU to control? Any Information would be greatly appreciated.

[RETed]

One wire is used as a voltage input for the internal voltage regulator.
I believe the FD needs a constant +12VDC.
This needs to be connected.

The other is for the warning light.
It triggers a signal to the warning light cluster to tell you there is something wrong with the (electrical) charging system.
This doesn't need to be used.


-Ted

[My5ABaby]

This may help. It's the alternator switch/changing diagram.

[FC Zach]

This may help. It's the alternator switch/changing diagram.

After looking at the diagram I would assume that the most logical thing to do would be to make a jumper wire to the (S) terminal from the (B) terminal. Does anyone disagree with me? Doing this will of corse be a constant 12v connection, so would it be better for me to run the wire to a fused/switch connection?