Battery Light (and More) Now Slight Plastic Burning Smell

[ctyoter]

Battery light came on a couple days ago and today on the way home, just as I was pulling into my driveway, the dash lit up like a Christmas tree and I caught a wiff of what smelled like burning plastic. Power windows felt sluggish so I think it's an alternator issue or I think a pulley and/or belt gave up the ghost but can someone point me to where I should start looking?

Otherwise, the truck's been fine.

Thanks!

 

[Kevin G.]

Suspect bad/locked-up alternator.

Check serpentine belt. Put VOM across the battery....while engine running. If less than 14.0 volts.......probably bad alternator.

Hope this helps.

Kevin

 

[ctyoter]

Suspect bad/locked-up alternator.

Check serpentine belt. Put VOM across the battery....while engine running. If less than 14.0 volts.......probably bad alternator.

Hope this helps.

Kevin

Will start there. Thanks Kevin G.

 

[dasx86]

Stock alternator only puts out ~13.6v except at cold start where it's in the 14v range, unless a diode mod has been performed. Not good for AGM batteries, but fine for lead acid.

Just dropping this note for anyone who might stumble upon this thread whose alternator is actually fine - seeing ~13.6 in the system at operating temperatures is normal.

 

[ctyoter]

So I replaced the belt to start and identified some crusty pulleys which I’ll get to later but by the time I did this my battery was dead so I put it on a charger overnight and got the green light. However, as soon as I connected the positive terminal I got that burning smell and it appeared to be smoke from the alternator. Upon disconnecting the positive it still smoked a little so I just unplugged the entire battery.

I might ask in a separate thread but I wonder if it’s able to be rebuilt or too far gone. OEMs cost $250 and up so rebuilding is an attractive alternative.

Edit: Went ahead and ordered a replacement alternator. Who'm I kidding; I woudn't get around to rebuilding the thing for about three years knowing me

 

[Cezar]

I'd also replace the battery while you're at it, unless it's very recent.

Stock alternator only puts out ~13.6v except at cold start where it's in the 14v range, unless a diode mod has been performed. Not good for AGM batteries, but fine for lead acid.

Just dropping this note for anyone who might stumble upon this thread whose alternator is actually fine - seeing ~13.6 in the system at operating temperatures is normal.

Yep. I'm on my second deep-cycle AGM after killing the first one with the stock charging system. The gm diode mod is cheap and easy to do and boosted my charge by a solid 1v.

 

[ArthurKotb]

So I replaced the belt to start and identified some crusty pulleys which I’ll get to later but by the time I did this my battery was dead so I put it on a charger overnight and got the green light. However, as soon as I connected the positive terminal I got that burning smell and it appeared to be smoke from the alternator. Upon disconnecting the positive it still smoked a little so I just unplugged the entire battery.

I might ask in a separate thread but I wonder if it’s able to be rebuilt or too far gone. OEMs cost $250 and up so rebuilding is an attractive alternative.

Edit: Went ahead and ordered a replacement alternator. Who'm I kidding; I woudn't get around to rebuilding the thing for about three years knowing me

I believe most parts stores can test your alternator for you. Take it off and take it to them; pretty sure it's free test.

 

[dasx86]

I'd also replace the battery while you're at it, unless it's very recent.



Yep. I'm on my second deep-cycle AGM after killing the first one with the stock charging system. The gm diode mod is cheap and easy to do and boosted my charge by a solid 1v.

How long did it take you to kill the AGM battery? Any other weird behavior noticed before it bit the dust?

I had bizarre electrical issues about a month after switching to an AGM battery, P0607 a generic ECU fault code. Only when troubleshooting later did I put it all together that I wasn't fully charging the thing. No diode mod here, went back on a lead acid battery, and the AGM sits in my uncles Grand Cherokee which puts out the necessary full time voltage to keep the AGM happy.

 

[MikeinNH67]

I just buy used OEM alternators as remans seem to be junk these days. Maybe if you can get one rebuilt by Denso it would be better.

 

[Cezar]

How long did it take you to kill the AGM battery? Any other weird behavior noticed before it bit the dust?

A year. Slow cranking and then eventually wouldn't start.

 

[ctyoter]

I'd also replace the battery while you're at it, unless it's very recent.

I’m thinking it’s about time for that too being about 4 years old.