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Charge, no Charge

You could also put the extended high idle mod on the PCM. IIRC, you can put a toggle switch between two of the connections on the PCM. This was for police use. If you search, you should be able to find out how.
 
Took more readings with the dvom. Taken from battery.
Engine off- 12.56 v
Running, all accessories off 13.86 v
Running, radio on 13.86 v
Running lights on 13.83v
running,radio, max ac on low 13.6 v
" " " " " " on hi 13.53v
running, lights, radio,ac/hi, HID fogs 12.23v
Crawled under, took same reading at alternator got 12.4 volts.

shut HID's off, back up to 13.5 volts.

Took it for a test drive with everything on,voltage on hiway,2K rpm was right at 12 volts. Shut everything off, came back up to slightly over 13 volts.
Belt is definatly not slipping. it is VERY tight. Dont notice a change in idle when aux fan comes on.
 
Sounds like your HID lights are drawing some serious current, because everything seems fine until you turn those on. Could those HID burnt out your alternator before?

From what I understand, those HID is suppose to draw a lot of current initially, but very little current once the lights are lit. But what if those ballast are bad and drawing high current all time.

I'm thinking your HID is the problem and not the alternator or charging system.

You might try this...I assume you have a ballast for the right light and one for the left...well, disconnect one and see what happens and then the other. Maybe one (or both) of the HID ballast are bad???
 
Will give that a shot. I rarely use them, but was using them to see what the charging system was doing. Even when they are not on, I can be driving with just the ac on, pull up to a red light, put on the brakes, and watch the voltage drop. I HATE electrical problems.
 
Could be bad cables. You'll never find high resistance in a power cable with an ohmmeter, time for a voltage drop test. Check opposite ends of the alt-bat and bat- ground cables with everything turned up high and meter on volts. You should see no more than a few tenths of a volt on the meter, any more and the cable is internally corroded and the resistance is eating up your alternator's output.
 
Oh, sorry...thought only the HID was pulling the voltage down. Saw in your earlier thread that lights and AC did the same.

Cables are always something to check...but I think you already checked for voltage drop...

"running, lights, radio,ac/hi, HID fogs 12.23v
Crawled under, took same reading at alternator got 12.4 volts."

Well, I'm thinking it could be one of the following...

1. It still could be your alternator...you said it was full field tested...not sure of the details of the test preformed by your mechanic, but it should be 'load' tested. Why load tested...well, for example, a 'bad' battery can give a voltage reading of 12.5V, which seems good, but under a load, it could drop well below 9V.

2. It is your PCM...it is not sensing the added electrical load and doesn't 'tell' the alternator to compensate.

3. Or as others said in this thread...the wiring...not just the main cables, but the wires that go from the PCM to the alternator...reason is...doesn't seem to be acting consistent from what you described.

Sorry can't be more help...but it is hard to diagnose something like this without being there.

But in all honestly, I'm tending to believe it is your alternator...even if it has been rebuilt...
 
Im having a very similar issue.. im starting to think its a bad alternator.. even though its brand new. Maybe my thread will help you:

http://www.naxja.org/forum/showthread.php?t=1002698

We have a different year vehicle... but it sounds like you have a similar problem as me. I take it if you blip the throttle, your voltage goes back up? When your taking voltage readings at the battery, does it very slowly give you lower readings?
 
How old is the battery???
Have you put a long Slow charge into it?
Check grounds engine to firewall and ones near PCM?
Cleaned batt terminals and cable ends?

My vote is weak battery or bad cables, grounds. Seems like its really trying to work. Bad connection or wire.

Might try moving cables around some while reading the DVM (Volts dropped). (If its been "flooded" with salt water the insides of the cables get eaten up, 'LOOK' Ok outside but SHOT inside .)

Good Luck,
O
 
Thanks Everybody. Battery is 4 months old. Have not put a charge on it, as it doesnt need it. Have checked and cleaned the grounds. Battery cable ends and terminals are clean as can be, no corrosion at all. Checked it with another PCM today. It still did the same thing. Could be wiring. Odd it just started, but no different than any other problems just starting up. Took it to John at Auburn Car Repair today, and he looked it over. He is ordering me an alternator tomorrow, as he thinks it may very well still be the alternator as well. Also found out I need a new AC compressor, mine started sparking as he was under the hood.... Should've kept my 92.
 
Muad'Dib said:
Im having a very similar issue.. im starting to think its a bad alternator.. even though its brand new. Maybe my thread will help you:

http://www.naxja.org/forum/showthread.php?t=1002698

We have a different year vehicle... but it sounds like you have a similar problem as me. I take it if you blip the throttle, your voltage goes back up? When your taking voltage readings at the battery, does it very slowly give you lower readings?
Click to expand...

Yes. When I blip the throttle, voltage goes back up. When taking voltage readings at the battery, in my opinion the voltage drops quite fast, not slow.
 
My daughters 87 4.0L is doing this same stuff. I am having the Alt checked today. I have changed out the PCM with one I had laying around, no change. I am getting power at Alt from the yellow signal wire when key is on....thinking Alt, but it was charging at 14V just a couple days ago.

I hope it tests bad, but I don't think it is. I had it apart and brushes and all look real good.
 
My 1997 did this EXACT same thing. It would show 13 volts for a second, but then drop off the face of the earth and bring up the check gauges light. After about an hour of run time (15 minutes with lights on), the lights got dim and it finally drained the batter. Replaced the alternator with a JY style alternator and its been fine since (minus it making the belt chirp in the morning).

My money is on the alternator
 
put the Alt back in on my lunch hour. It is charging at 14V.

Could the starter relay be doing something strange or should I just spend more money and get a new alt?

_I really don't like intermittant problems.

Thanks,
D
 
To my JY means junkyard. BIG HELP! Go through your connections and grounds. Don't forget that you need a complete circuit, not just the power side. Intermittant sucks. It's better when it just breaks, especially if it's near home. Then you can fix it.
 
ended up with a new alt after it quit charging in the driveway. Hammer tap got it going....so off to the parts store for a new one. New one is working. Hopefully for "good".

Thanks.
 
Well, just got the Jeep back from the shop Monday. Was out of commission due to theft. They broke in, and tried to steal it, but the awesome chip in my key kept them from getting it. And to think, I've been looking at ways of overriding that chip, cause I am too damn cheap to go get a second programmed key made.
Put in a new alternator today, and seems to have taken care of the problems.EXCEPT when I turn on the A/C and defrost, etc. on High. Either a prob with the blower motor, or the fact the clutch is going out on my AC compressor, is maybe putting too much drag on the belt. Next will be replacig the ac compressor, and maybe that will finish fixing my problem.
 
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