1990 Lebaron 3.0, problem with charging circuit

That would make sense. 60 mA is a lot of idle draw, but many cars are like that now.

There are fusible links all over the place. Measure continuity between the positive pole of the battery and the output of the alternator. Make sure the two are connected together and the fusible linke between them is not open. Make sure there is continuity between the alternator ground and the battery ground; sometimes damaged ground straps cause weird problems.

The voltmeter was reading _high_ but the battery is not charging? What is the voltage across the battery when the engine is running? After you drive around a little, is the idle voltage across the battery higher or lower than when you started out?

You may also have an alternator that is producing too high a voltage because of a regulator failure, and is damaging your battery. The meter will tell you. The meter is your friend.

--scott

This is a very simple charging system, a few voltage checks and jumpering one wire to ground will diagnose 99% of all charging system problems.

Also; did you check for trouble codes?

I took an alternator in once to Parts Source. They tested it out right there on the spot. Maybe a parts store nearby will test it out for you. Call before you go so you don't waste a trip.

I haven't driven it since I parked it. Battery read 12.2 while engine off, 11.8 while idling. When I did drive the thing home the other day, ANY accessory would cause the dash meter to dip - even putting the radio on and turning up the volume enough.

Before the batteries starting giving out, yes the meter on the dash was reading on the high side. Can these alternators be rebuilt (I know that there are kits for other alternators for sure)? Do these things have ball bearings or sleeves? The original alternator I still have, too it off the last time I had this problem, and installed the largeish one that came was in the trunk (came with the car). It's bigger then the old one, but still fits. Been running with that one since last march. Problem with the original is it seized up. I'd probably want to replace electrical stuff in the larger one that's currently on the car, because I don't know if I could *unseize* the old one. Soldering and stuff is not a problem.

Right, so those part generally can be replaced (the ones internal to the alternator)? This car is a darned good runner, but I really don't even feel like putting in the price of a new/rebuilt unit if I can help it.

Okay, good.

It would be very unusual to have a charging system problem and

-not- have any trouble codes stored. There are codes for low voltage, high voltage and field circuit problems. Not all problems will trigger the check engine light even though they do store codes, so, don't assume that because there is no CE light there aren't any codes stored.

They tell me much.

Okay, you've got 12.2 volts across the battery engine not running, you've got 11. 8 volts with the engine running, that is obviously a no charge condition.

Refer here;

The terminal labeled B+ should have the same voltage as what you measured across the battery. This proves continuity between the alternator and the battery. There is a fusible link in this circuit.

The terminal labeled A142 supplies the alternator field with 12 volts whenever the ignition switch is in the on position. Fuse #16 protects this circuit.

The terminal labeled K20 is toggled to ground by the SBEC (engine computer) at the SBEC it is terminal 20 and is a dark green wire.

Knowing all this, all you need to do is check for voltages where they should be under the conditions I described.

Next, connect (key off engine not running) an ohm meter between the A142 and K20 to check continuity thru the alternator rotor and brushes.

If all is good, with the engine running, connect a jumper wire from K20 to a good ground, this is called 'full field' you are now bypassing the voltage regulator function of the SBEC, if the alternator is now charging, you have a wiring problem to the SBEC or the VR in the SBEC is hosed.

You'd said that, and that makes perfect sense if your alternator was not functioning or no longer connected to the battery.

But then LATER you said that your dash meter was reading HIGH by a couple volts. Are both of these actually the case?

Wait, wait. The old alternator seized up, and you replaced it with one that is a different size. You didn't mention that at all.

Okay.... that sounds like your problem. Where did you get this replacement from? Was it from a legitimate rebuilder or a cheesy chain store?

For the most part, it's so cheap to get a good rebuild done that it's not worth your time to do it yourself. Take the old one to a local starter and alternator rebuilder and have them do the job. It won't cost much. They will replace all the bearings, the brushes, turn down the commutator, inspect, measure, and load test everything without charging an arm and a leg.

--scott

Let me start over. About the time I left the lights on and drained the battery (a little before or since then, can't really remember) the dash voltmeter was noticeably higher then normal. Then a week later I guess the battery got drained (started it one morning and CE light was on, subsequent starts were a little strained, then finally that battery got too low to start engine). Replaced battery, drove it, noticed meter was down sometimes at this point, about where it should be at other points in the journey, but mostly down. Then measured voltages with multimeter as reported.

When I bought the car from my nephew, there were a bunch of parts in the trunk. The current alternator is physically larger then the original, but *fits*. So since this is a beafier unit, that's what's causing the problems? I didn't think that would be the case. There are different alternators for a single car, whether you have AC or not. But we don't always run out AC's.

Sure if that's the problem. No big deal, I'd buy another alternator. I just don't want to find out that my battery still isn't being charged. Thanks for the help by the way.

Okay, and this is all with the new alternator, right? The alternator had been replaced before you got the car, you say?

Where did this alternator come from? Was it from a legitimate rebuilder or a cheesy chain store?

So, take the voltmeter and measure the voltage on the output terminals of the alternator with the engine running. If it's as low as the battery voltage, the alternator is not functioning.

If the alternator is a cheap chain store rebuild, it's almost certainly the problem.

--scott

right. The *new* alternator that I found in the trunk. When I had a similar problem with this car, I put the *new* one on, and that wasn't the problem (it was the fuse).

Probably a cheesy chain store. Best guess. That would denote a cheesy rebuilder (generally). Rebuilt ones from Carquest or Advance are about

Ok, will do. I'll probably also take it to the parts store to have them test it.

Like I said, I still have the original alternator (right size too!) but I left it outside and it won't spin. I sprayed it with PB, but that might not do it. Worst comes to worst, I may try to dismantle it and replace the bearing even (with a small harbor freight arbor press?). Being that the thing seized, that seems to indicate to me that there are ball bearings in there. I could probably also try to install them by tapping with a socket in place. Don't know... Don't really feel like dropping ~150$ into this old thing. Like I said a great runner, but old is old...

So, you bought this car, and it came with a spare alternator in the trunk.... and before something failed and you put the spare alternator on, but it turned out to be a failed fusible link.

Ohhh-kay.

The chain stores hardly ever carry rebuild kits, because they want you to buy their crappy rebuild. Stay away from Carquest and Advance and take the alternator to a real alternator rebuilder.

What parts store? Most of the chain stores aren't really staffed with people I'd trust anywhere near my car.

Take it to a real alternator shop. Look in the yellow pages under "Alternators" or "Starters."

ANY car that comes with a spare alternator in back is kind of suspect. You're sure the alternator you put in isn't one that had been previously replaced?

--scott

Oi no, it was a bad fuse that was preventing the charging circuit from doing it's job. The first guess is the alternator, no? So being there was one in the trunk, I threw it on (and left it on). That's when I realized the old alternator wasn't bad. Oi.

Well I called a rebuilder and he wanted 98$ for a rebuilt unit, with the swap. Car quest wants ~142$ for a rebuilt unit. So...I called the junkman and he had one on the shelf for 40$. I threw it on and it works. Now I have 2 old alternators (he wanted my old one, but I opted to pay 5$ to keep it). I want to learn how to replace bearing and fuses and diodes (basically that's all there is I reckon - regulator is in the computer). Winding rarely go bad on these things I take it, but even then I could have someone rewind it for me.

The Carquest near me has a few gurus on hand. At least one dude is pretty professional. And yes I did take it to them to get tested, and they told me it wasn't putting out (he was of the persuasion it wasn't bad brushes, but probably bad diodes).

Well my dopey nephew used to work at a NAPA, and I'm thinking that's where/when he got it. Neither the spare battery cables nor the alternator were right on, but the alternator did work at least (for the better part of 10 months basically). Anyway problem fixed. Thanks for all the help!