MX-3.com

Ok so last year I had alternator troubles...no wait...lets go back further...

2 years ago my original stock alternator died so I went to Canadian Tire and got a Champion reman alternator for a little over $300. I figure 3 year warranty...we're good to go for a while. THEN last year as winter was approaching, I noticed that every time I turned on the rear defroster I could smell something "melty" coming from the engine compartment. This turned out to be because the defroster was shorting (i think) and drawing too much current from the alternator causing the main wire on terminal B to over heat and basically melt the plastic around the terminal...and overheat the rectifier which failed. So CT warrantied the alternator and I replaced it and I haven't used the defrost since and have had no problem.

But then last night the damn charge light came on and I looked and the terminal B wire had broken right off and there's like charred crap all over it and it was SUPER hot so I don't know wtf is going on with my charging system. I should be able to get the alternator warrantied again, but I need to figure out why this is happening.

Offer your suggestions. Please.

2 things I would check, when its hooked up get a readout on how many volts its actually putting out as well as when you take it off see if they can bench test it to see if the regulator inside the alternator is fubar'ld and just dumping to much voltage.

Atleast then youll know if its the alt or something in your car.

This isn't going to help but I would never by a remanufactured anything. I either bring the stock regulator to an auto electric place for a rebuild or i get one from the wreckers. One way or the other I have a shop remanufacture it and bump up it capacity. You can go 120-130 amps no probs for about $160 including rebuild..

Well at this point I know that my alternator is not functioning so I’ll go about replacing it first. From there I will start checking possible causes. That is good advice…I will do that. I’m curious if any of you have had a similar symptomology and what fixed it for you.

Well if the light comes on it's either, the belt, open diodes, open circuit in stator windings, open charging system, open field circuit, worn brushes, defective voltage regulator.
If you know one of the automotive guys at CTC ask them if these alternators are crap of not.

Funny, Murphy on MX6 has this posted on his profile.
1)if it ain't broke, don't fix it.
2)Champion alternators suck.
3)Don't buy from Part Source.
Just thought I'd share that.

I agree on "Champion parts suck"

Wyt: Take your tools to the store, replace the alternator, and ask them to test your charging system. The problem you're having may be caused by the problems Dan stated (one or more of them) and by many others. Basically, you're overloading your alternator (duh!), which can be caused by a short circuit, almost anywhere in the car.

And, while you're at it, get a big bottle of patience pills. Diagnosing a short circuit is very easy. Finding it can be a PITA on steroids.

quick question, why dont you see if they'll let you get a millenia alternator for a replacement and just modify the pigtail. More ampres is a good thing

I have been going over this with help of a mechanic buddy that I work with and we believe that it must be directly related to the defrost system.

Clearly the heat in the regulator/rectifier is being caused by a short in the car somewhere. Any lighting system, or accessory such as a heater fan or radio would stop functioning if it had a short circuit...so I can't see it being any of those systems. Furthermore, none of those systems draws enough power to cause a draw on the charging system great enough to overheat that 4G wire.

Now, if the defroster relay is stuck in the closed position, or the circuit is shorted between the relay and the switch, power would be constantly on and going to ground, causing the defroster not to work.

My plan is to replace the alternator and then start the engine and put an amp clamp on the output cable then pull the defroster fuse. If the defroster circuit is shorting and has power...the output should drop when I pull the fuse. If it does then I know the draw is in that circuit...if not...the chase begins.

Sleeper6 wrote:quick question, why dont you see if they'll let you get a millenia alternator for a replacement and just modify the pigtail. More ampres is a good thing

I actually already have a Millenia alternator on the shelf with the harness...I have just not felt the need to go to the trouble of changing the wiring over. I will at some point.

just out of curiosity check the defrost relay under the dash see if its melted, there is a 40 amp fuse in the engine bay that feeds power to the 20 amp relay under the dash, see if someone jumpered it to make it work or if the relay has melted into a nice pile of crap. Short of that I would do a current draw test on that circuit see what kind of juice it is pulling, to kill an alternator you need to have a huge draw somewhere in the neighborhood of 100 plus amps. The battery should be taking the brunt of that draw not the charging system. As an added option if you are replacing the alt I would also upgrade the charge wire to a 4 gauge wire and replace the engine ground. If you do not want to do that at least do a voltage drop test across the charge wire see what kind of shape it is in.

I figure it's a pretty safe bet that the cause of the whole thing is the defroster relay. I've had them blow on other MX's I've owned. It's the only thing in the car that can draw enough power to kill the rectifier. My guess is that once I get the new alternator in and pull the main defroster fuse the current comming out of the alternator will reduce significantly...telling me that it was grounding somehow...indicating the relay is fried.

I do plan to replace that wire with a bit of 600 strand 4G I have. When I installed the engine I relocated the battery and did all new grounds with the 600 strand wire so I'm pretty confident of that. I did not replace the section to the alternator, so I will do that tomorrow.

Now I have to find a defroster relay.

EDIT: Looked it up...all 90-92 MX-6 and 626 use the same relay. Rockauto rules.

I use to own a high performance, push you back in your seat chick magnet called a Pontiac FireFly and before the Alt. went in that car it use to get real hot so I'd have to pull over and let it cool. I finally replaced the Alt. and no more problems. You could just be getting a rash of shitty made Alternators.

Well I warrantied the alt last night so I'll pop it in tonight. I borrowed an amp clamp so I can test the output of the charging system with and without the defroster main fuse. I think that will tell the tale.

Yes that's the ticket, if it's in specs you know it's the crummy Alt. Seems like you got your warranties worth so far.

OK...so I'm a little frustrated.

I installed the new alternator and of course it starts right up and runs same as ever. I turn off all the accessories and put the amp clamp on the output wire of the alternator and it reads like 39.5A. OK. That seems totally reasonable. I pull the fuse for the defroster because I suspect that there's a short in the relay and this will definitely kill any power being drawn by the defroster circuit. No change. So apparently there is no mystery load due to the defroster. Then I turn on the defroster and the draw goes up to 58A. Still totally reasonable.

So it's a 90A alternator and the battery is only drawing <60A...but for some reason the rectifier fried.

I"m going to replace the output cable tomorrow all the way to the battery with 4G 600 strand wire just because I think it's a good idea, but this doesn't explain to me why my alternator cooked that cable in the first place.

Any thoughts?