hen3ry

iTrader: (1)

car: 90 gxl

So recently, all the idiot lights came on. I figured it was the alternator.
I bought and installed a Mazda Reman Alt, but the problem persisted.
I had both the battery and the new alt tested and they tested fine.
I cleaned the battery cables and put new battery terminals on.
I cleaned and reconnected the wires that bolt to the fuse box.
At first these steps seemed to fix the problem, but after 10 mins of driving the idiot lights popped back on and I'm running at 12v again.
Checked voltage at B terminal with car off and got battery voltage.
Checked voltage at the alt connector with key to on and got battery voltage.

What could be causing this? What should I be checking?

Thanks in advance.

satch

iTrader: (1)

But what was the voltage at the B terminal while the car was idling? If you don't know then it needs to be checked.

hen3ry

iTrader: (1)

Got battery voltage from B terminal at idle.

satch

iTrader: (1)

It needs to be 14.1 to 14.7 volts at idle.

When you had the alternator tested was it removed from the car?

Where did you get this alternator from? Mazda?

hen3ry

iTrader: (1)

It was tested out of car.
I got it from Mazda dealer.

satch

iTrader: (1)

I suppose the belt could not be the proper tension but it appears that the alternator just isn't cutting the mustard. Also, this notion of having the alternator tested while sitting on a counter top and not in the environment it was created for is bunk! This isn't against you personally, but I've heard countless stories where it tested out fine not in the car but!!!!!!!!!!!!!

satch

iTrader: (1)

Is your alternator wired as in the diagram included?

hen3ry

iTrader: (1)

yes the wiring is correct.

thejallenator

iTrader: (14)

[QUOTE=hen3ry;10113763].
Checked voltage at the alt connector with key to on and got battery voltage.

/QUOTE]

was the motor actually running or was the key just in the "ON" position.

if it was running i'd take that alt back and get my money back

88rota

iTrader: (18)

I had that problem with all my death light coming up to!!!

It would it then go away then it came back. I pulled the alt and sent it to a alternator shop and was going to have the alt rebuilt for more amps because the second gen alts SUCK! But I was told there isn't enough room for the stater to be beefed up. So he went above and beyond and got me a 3rd gen alternator for 135.00 bucks and beefed up the stater to 135 amps. BOOYA it worked great and I've haven't had one light pop up on me yet!

Also try to rewire your charging system and grounds with some good power wires like for a car amp for a stereo system.

hen3ry

iTrader: (1)

searched some more and found this link from hailers:
http://www.aa1car.com/library/charging_checks.htm

went through and found on testing for voltage drops
B terminal to + batt was <0.1 volts consistently
Alt housing to - batt was consistently 0.2v < x <0.3v

I guess this means i have poor grounds, but i was just wondering if that were enough to cause my symptoms.

HAILERS

Remove the small, two wire plug on the alternator. Key out of the car.

The white wire with a blue stripe should have batt voltage on it. Does it? It's the power for the alt regulator.

And or try this. Start the car and verify it is not charging. Now quickly rev the engine to over four grand and go back to idle. Is it now charging?

The test in the post directly above this post, while useful won't help in this case. IF it were putting out say 13vdc when it should be putting out more than 14vdc, then I'd look into it, but yours does not charge at all the way I understand it. So to me that means the alt is not getting excitation voltage or it's regulator is just kaput .....one.

The alternators guts get their ground from the body of the alt mating with the attach brackets. But in your case that is not the reason the alt is not putting out imho. Either a bad regulator or?? Regulator is inside the alt and you need to solder one in if the one that is in there is bad.

hen3ry

iTrader: (1)

White/Blue wire has battery voltage on it.

So, if the regulator is bad, would it still test normally on a bench test?

I guess all the signs are pointing to getting another alt.

thejallenator

iTrader: (14)

if the regulator is bad yes get a new alt. its not worth trying to beat around the bush, trust me i have a nice stack of burned up ecus that will tell you the same thing......

HAILERS

************************************************** ************************************************** ************************************************** *

Alt sounds bad. But sometimes an alt will SELF EXCITE! all by itself with a bad regulator. This is done by idling the engine.........then suddenly reving very high and letting the rpms drop back down to idle or there 'bouts. What happens is there is some magnetism (sp) in the rotor of the alt and when you rev high there is enough to cause the alt to self excite and put out like your girl friend (humor, please).

IF yours does not do this..........seems to me the alt is probably bad. I've no idea how they check out alts at the autostore. WELL actually if it Does start putting out the alt is bad or at least it points to the regulator not exciting the field. Bad is bad.

I believe there are procedures in the ENGINE ELECTRICAL seciton of the FSM that give some insight/clues on what might be bad.

Seems one test is they have you check the other wire in that two wire alt plug, with the key to ON, engine OFF and that wire when connected to the alternator should show approx 3vdc. MIght try that. You'd leave the elect plug on the alt and backprobe that wire with ???? say a sewing needle pricking the wire??? say ..yes. Use the case of the alt for your meters negative lead when doing that.

The grounding of the alt is pretty simple. Alt case makes contact with it's mounting bkts to the engine..........engine is connected to the batt neg terminal thru the large cable of the batt neg cable being connected to the starters long outbd bolt (or any of the transmisions/engine attach bolts. Basically if the starter spins over the engine/batt are grounded to each other. I'd need no other proof myself.

IF the output of the alt was lower than what most say it should be (14.2 to???? whatever), then the problem might be a iffy gnd b/t the alt case and the engine. Like the attach bkts might be painter or corroded or ????? Cleaning up the corrosion might very well make the low output come up closer to spec. BUT that is not your problem in my opinion since it won't charge at all.

hen3ry

iTrader: (1)

I'll try replacing the alt.
Thanks for your help.