99 alt inop after new alt and thermistor.

[moparman]

weird thing is the batt light was on with on with old alt and not on with new one>? 12.1 volts all it shows, fuses good grounds good new ac declo batt

thermistor checks out good,all grounds cleaned.

[moparman]

this is a 99 with just under 99k and always west texas car no rust! GM alt with test sheet

[RCA1186]

Not starting? 100% sure the battery is good? Did you have it tested? (even if new)

[quixote]

Just a shot in the dark, but I'd go checking ALL the ground points, maybe check for wires that might have been chewed by rodents, if the car has sat for any period of time.

My '98, with a new battery & cleaned grounds, shows 14 volts on the battery.

I'd also go looking for a fairly fine wire (roughly 16 gauge), on the passenger side of engine compartment, near the bracket just to that side of the intake manifold (easily visibile on the top side of the engine compartment)... I don't know if it's some kind of ground to the starter, or what. If you are looking for it, the wire is pretty obvious, assuming you can see the break.

My starter failed out of town, so I had a local garage replace it. They damaged that wire, & about a week later, the car would not start until I found and repaired it. It's long enough ago, I can't remember if the car would crank, or not ---but it would not start with that wire broken. (I just cleaned up the ends of the break and put a wire-nut on them.)

I hope this helps. If you are a Dodge guy, these engines must seem like some pretty strange stuff.

[moparman]

it starts fine, runs drives fine . when check charge came up i saw 12 volts on screen abd tested at battery sure enough 12 volts.  red batt light on left side of dash on also so i figured yep 100k needs an alt. new alt installed red batt light out but still showing 12 volt on info screen. yay pulled alt again had bench tested a ok! DAM IT DID ground upgrade and cleaned every ground i could fin d no change. Pcm? expensive  bitches these Auroras but i still love em. batt less than year old and its an A/C delco alt is a GM dealer alt not cheap either. not opposed to changing pcm but i hate just throwing parts at this, i am an ASE master tech have been for 40 years! lol acceaa to a flow chart and or wiring diagram would be great i cam only find lame junk pics.

[quixote]

Sounds like you are so far beyond me, I should just be quiet, watch, & learn.

If I understand fully now, everything seems to be working fine, you just have a warning message to check charge?

If I have a clear picture of your situation now, I think I'd just get one of those lithium ion jump-start packs (in case the warning is NOT bogus), charge it, throw it in the trunk, and drive the car around until the 'problem' proves to be true.

If you search through the old posts, a lot of people have had trouble with aftermarket or rebuilt alternators. You say yours is new ACDelco & tests good, so I guess that doen't help you any.

...If you look through back posts, you will see lots of people having to fix individual wires, out of the twenty or so going to the driver's door control panel. I don't see how this could relate to your issue, except as an example that Oldsmobile didn't mind throwing a few more wires at a 'problem.'

[moparman]

new pcm no change

[AuroraGirlFromMars]

is your alternator output tested At the battery or at the charge wire in the engine bay? The AD series alternator should have a sense wire that find its way all the way back to the BEC under the back seat. There is also a temp thing that is used for the car too. i dont know hjow it works but thought to mention. If you are getting output to your battery, you could have a bad ground for IP/DIC stuff

also, check your charge wire for voltage drop

[moparman]

fixed it 14.4 volts at idle 13.9 full load, 3 wire plug at alt was obvoiusly bad.  new alt new ac compressor plugs coils wires ground upgrade added 3. almost sold it for scrap finicky beeotch! runs mint

[paulaurora]

I dono why everyone keeps wanna change PCM this is the last ting that will go bad. Its more common on new cars but not on Older cars.

[RCA1186]

Glad you got it taken care of.

[AuroraGirlFromMars]

Aug 23, 2021 19:19:44 GMT -6 paulaurora said:

I dono why everyone keeps wanna change PCM this is the last ting that will go bad. Its more common on new cars but not on Older cars.

infact, assuming not a physical failurr, one can usually get the updates rather easily for old gm pcms if someone needed to update the pcm to fix a known bug.  just need a passthrough device and a few bucks to Tisweb2000