weird goings on 99 expy

[Kermit]

OK had an incident today where my truck stalled and wouldn't start without a jump. Battery light came on intermittently yesterday. Wasnt on when I started the truck, then after driving a short distance the light came on. Same thing every time I started it and drove yesterday and today. Guys at advanced auto think alternator.

Today drove a short distance, under 10 miles, same thing, no light when started, drove like a mile and it came on. Had a Dr appt, came out started right up, went next door to get scripts and while idling in park motor was running kinda rough, battery light was on, then i got like a surging idle that actually rocked the truck a few times then it died. Hubby put a meter on the battery post and got a 12 volt reading. When I tried to start it after the stall ALL gages spiked then went back to normal, cranked then dies, no start. Hooked up to jump and started right up... Drove the less than 5miles home, no rough idle, battery light on but no stall on the trip home.

Hubby doesn't think alternator since the battery had full charge. I know I have some electrial gremlin somewhere cause sideview mirrors will sometimes be moved, odometer goes in an out, sometimes lit sometimes not, sometimes goes out when I turn on lighs, sometimes not. Driver window even opend one night, and that mirror moved pointng all the way outwards. Weather doesn't seem to play a part with my gremlin, happens in all conditons. Mileage just a tick over 200k... I think that's everything...

Thoughts?

 

[Bedrck47]

Have hubby check the battery voltage with nothing on Then start and check voltage Then rev engine to 1500-2000 RPM's and read voltage. Also check all electrical connections on Battery and Alternator for looseness and or corrosion.
Post the above voltage readings

Rather than Guys at Advanced Auto Thinking what could be They should have checked it and that way they would know.

To be honest I don't trust people that say THEY THINK the problem is I want someone that can say for sure what the problem is.

The odometer light is a normal problem on the 1st gen expys and is a simple fix Plenty of videos on youtube on how to fix it

 

[Bedrck47]

How old is the battery. Doesn't matter if a battery shows full charge, What does matter is what the battery does when it has a load on it.

 

[Kermit]

Battery was in the truck when we're bought it so maybe 2ish years old, dude said just replaced before we bought it. Yeah I was kinda ticked advanced didn't just check and assumed the problem was alternator.

 

[Kermit]

Ok, prestart 12.42 immediate post start 12.14, revved at 2000 rpm 12.10. All connections look/feel good but hard to see right side of alternator hard to see in lake effect snow... Will get better inspection tonight when he can pull it into the shop. No corrosion noticed on battery ports, no corrosion noted on alternator wires but all are in those plastic casings. Casings didn't look crackd or marred at all.

 

[Bedrck47]

at 2000 rpms you should be seeing 13.5 to 14.5 volts Check the belt tension on the alternator. if belt tension is good I would say the alternator needs replaced.

Advanced may be correct but testing is the best way to check it.

You may be able to get an alternator on e-bay for less than advanced unless your in a hurry

 

[Bedrck47]

Just sent you a PM

 

[stamp11127]

One more test to prove alternator failure. Since it is a northern vehicle that enjoys salted roads in winter it would help to prove the ground isn't the problem
Engine running @2000rpm, red lead of meter on alt output post, black lead on alt case. Scrape case with lead to make sure it is a good connection. If reading batt voltage then it is a failed alt.

 

[Kermit]

Thanks hon. Will do... Partsgeek had some decent prices, like $80-100.

 

[stamp11127]

There is another possibility but before getting into that I would have the current alt tested after removal.

 

[Kermit]

Thanks stamp, will update after testing.

 

[Kermit]

The alt tested fine but the battery came back with some wonky readings.

 

[stamp11127]

Who tested the alt and did they give you a printout of the alts performance or did you see the readings?
They should give you the output voltage along with amp output. If their tester just gives a green light then they are "Clueless on Earth".

Can either you or hubby read wiring diagrams? Next step is to verify voltage to the field coil (sense voltage) at the alternator plug.

 

[Kermit]

OK, update... Had the alternator tested at auto zone. Plugged the test unit into it an got a reading of 14.5 volts. Tests that battery, came back questionable. 1st test while truck was off read good at 12, good... started the truck for the second test came back reading 11.5, questionable... Bought a new battery, had good results for 2 days then the light was on again. Upon closer inspection found an idler/tensioner pully that was seized up, got new one and belt... Installing today. Posts about getting a belt diagram and any tips for this job on a new thread.

Sooo that's where we are right now.

 

[stamp11127]

I've added a sticky in the electrical section titled "Battery 101" to guide you on the voltages you should be reading with a meter.

 

[Kermit]

OK so according to what I gather from your post stamp my battery was only at 25%charge and below, ugh. How any the alternator test? What's the good range on that?

Got the pully and belt replaced, jumped the truck, within 2 minutes of taking the cables off it died, thought it was cold (below zero with wind chill last couple days), or gas lines, jumped again, with called still hooked up battery was reading 13.5 at the post, removed cables, checked battery, reading 7.5, so it's like we're not even taking a charge or maybe grounding it somewhere?... Idk... Thoughts maybe a broken wire somewhere, but not taking a charge at the post is concerning.

Thoughts?

 

[stamp11127]

Watch this from "Eric the Car Guy" and let me know if you have any questions.

https://www.youtube.com/watch?v=FTGz0PKIl84

 

[Kermit]

No questions so far. Will do these tests in morning. Thanks stamp.

 

[Texpedition45]

This may sound stupid considering all of the work done so far, but hace you checked tour grounds? I had a weird intermittent issue with the charging system and electronics that ended up being a bad ground to the battery. One cable and terminal later, and it's been just fine.

 

[Kermit]

Hey TeX, thanks for your input. We checked all the connections, cleaned some, made sure we had good contact, charged the battery to 12.9, sat overnight in minus 10° weather, stated right up this morning, gauge read on the high side of the half mark on the gauge, took it on the highway for about 20 miles, battery light on the whole time but no stall. Went shopping for an hour, came out, started right up, gauge still on the high side, got on the highway and the gauge started to drop like something was putting a hard draw on the battery, you could just watch it creep down. Never bottomed out tho and made it home... Hubby's thinking we've got a positive leg somewhere that's grounding out intermittently cause we're good for a while then we're blah... I don't even know where to start looking... Was thinking about bypassing the external voltage regulator but... I dunno... Thoughts?