[Speedy]

Hello everyone,
I have a '93 wagon that's not producing enough power to recharge the battery. I've tried 3 different alternators, all of which tested out fine at NAPA.
When I test the alternators, while the engine is running, I get a reading of 12 volts or less, the voltage drops as I turn on lights, a/c and stereo. I get the same voltage reading at the battery terminals.
I've checked just about everything I can think of, anyone have any ideas?

Thanks, Speedy

 

[dave8338]

Either the main lead from the alternator is bad OR there is corrosion in the connections/grounds, OR you have the wrong pully size on the alternator.

OR a combo of the above...

 

[Obliterous]

Either the main lead from the alternator is bad OR there is corrosion in the connections/grounds, OR you have the wrong pully size on the alternator.

OR a combo of the above...

I've had this exact same problem, and Dave has the right o it. Check the wiring between the alternator and the battery for corrosion.

 

[zzyzzx]

At idle I get 14-15V, but that's not necessarily always the case with all cars or all alternators. You should be checking it at 1500RPM with no A/C, headlights, or rear defoggers. I'm also assuming no serpentine belt or pulley related problems. I would also check all your electrical connections (including battery connections).

 

[Speedy]

Okay, I've replaced the entire wiring harness, including the fuse box and still no luck. Of the 3 alternators I've tried, I had the one with the smallest pulley on the car and still no charge. Infact, when I test it with the car running, the alternator doesn't hold the voltage, it slowly drops from about 12.14 volts and just keeps dropping as the car is running. It seems like the alternator isn't putting anything out and I'm actually only getting a reading off what power the battery has left.

Speedy

 

[madmatt2024]

Have you actually disconnected the alternator and checked its output voltage like that? Your battery may be toast or you have a huge current draw when the car is running.

 

[Speedy]

Yes, I've tested all three alternators at NAPA and they all check out fine, as does the battery.

 

[madmatt2024]

I meant testing it in the car. Disconnect the thick positive wire, start the car, and measure the voltage at the output. If it has good output then run a new wire from the alternator output to the battery and retest.

 

[Speedy]

I will test the alternator like you suggest, but I have a feeling that the voltage will be low and I've already replaced the wire once with a wiring harness from an escort that doesn't have any problems.

 

[PonyExpress]

then obviously you have some issues in the wiring from the voltage regulator out-

if the alternators bench test fine, that isolates that, if the battery is fully charged (and i hope youve been charging it after its been draining down all these times).. and the wire between the output post and the battery is good, then its plainly a problem somewhere else.

the only other connection in that circuit is the voltage regulator wiring or the single stator wire... you need to check those.

 

[Speedy]

Yes, I have been recharging the battery each time. HA! Okay, so is the stator wire the single wire that comes off the alternator right next to the positive wire? Is there some sort of fuseable link that excites the alternator into charging?

 

[drommer]

Same thing happened on my Race Scort. Check fuse under dash labeled METER.

Haynes Book Page 12-24 for wiring diagram explanation.

 

[Speedy]

Thanks for the idea Drommer. I checked the "meter" fuse and even replaced it with a new one and nothing changed. In fact, I changed out the alternator again and still nothing.
I can't believe that I have 3 non-working alternators, especially since two of them tested fine at NAPA and 1 was pullled from a running escort that didn't have any problems.
I've replaced the entire wiring harness under the hood, including the fuse box, which was again, pulled from a running car, cleaned all the grounds and checked all the fuses in the fuse box under the dash board.
When I test the alternator with out the engine on, I get the same reading as the battery and then I get the same reading when the car is running.

 

[None]

When you first turn on the key is the battery idiot light illuminated?

I remember from my old Volvo that this idiot light was in series with the excitation circuit and if it were burned out, the alternator would never start charging.

Just an idea.

None

 

[Sparky34kv]

Not to be stupid, but. Did you disconnect the battery once the car started? I had just gotten my 91 wagon back on the road last fall when the alternator/battery went. I don't know which went first, with the voltage regulators in them today the alternator is not designed to charge a dead battery, it burns out the regulator. When I checked mine I started it with the new battery, then disconnected the positive cable on the battery, instantly the engine died. If you are seeing the voltage drop as the car runs, with the battery connected, it is probably the battery that went bad and is killing your alternator. Are they checking good before, and after you have them in the car?

 

[madmatt2024]

When I test the with out the engine on, I get the same reading as the battery and then I get the same reading when the car is running.

I said to disconnect the positive wire from the alternator, start the car, and then test it's output.

I just noticed that you said your battery voltage is only 12 volts or less. A healthy battery should read at least 12.5 volts, probably more like 12.7.
The disconnect the battery while the car is running sounds like a good test. The alternator should produce enough power to run the car by it self. be sure to do something to bump up the idle before you disconnect the battery. If the car keeps running then the alternator is working. Otherwise your problem has me stumped.

 

[dave8338]

Have you actually disconnected the alternator and checked its output voltage like that? Your battery may be toast or you have a huge current draw when the car is running.

I second and third that. Load test the battery and report back.

 

[Speedy]

NONE, you're a genius! The problem has been solved!! The battery check light was not coming on so I followed NONE's thought that maybe it was part of the circuit. Well the light wasn't burned out, but the wire pack that plugs into the panel that has the battery light and several others, had some how come loose and was no longer connected. I plugged it in, started the car up and BAM, 14.5 volt at the alternator, problem solved!!! Thanks everyone for all your help.

Speedy

 

[None]

Awww Speedy....you is embarrassin' me. Keep it up. Don't stop.

Ok seriously now, I'm very pleased that your alternator is finally working and that I was able to help.

None

 

[Green91Goblin]

I'm having a similar problem, but mine will run just fine, done pretty much all the OP said he did, except I only changed 2 alts and no harnesses. Will jump off just fine, and will do good with a battery charger connected. Once I get it started, it'll run like a top (sounds like it has a miss though) and as long as I leave it sitting still, it'll fire up every time. NOW, my problem lies in when I go somewhere I.E. Cig store (1/2 mile round trip) and I get back home (I don't cut the car off due to the crazy problems I've been having) and I kill it, it won't start again. Turns over, but no start.

What am I missing here? I've looked this thread over and over, and finding nothing I didn't already check myself besides the fuse under the dash. Could I test light the fuses and see if there's one drawing current while the car is off, or what seems to be my problem? Both alts were bench tested and working fine, battery is new-ish.