My '02 540iA has 123k miles on it.
I replaced the battery in March of 2012 at approximately 115k miles with one from Autozone.
My alternator went out in August at 119k miles and I replaced it with a rebuilt from a local auto electric shop. All was fine and dandy afterwards. Voltages were in the 13.8 range on the unlocked OBC - not as high as I expected, but were varying as I'd expect so I assume everything was fine.
The alternator went out again in February at 123k miles. I felt like the car wasn't cranking as quickly the past 6-8 weeks, but its been a lot colder and there wasn't anything I could put my finger on, so I didn't really think much about it.
I finally got it back to the rebuilder to be evaluated. He was... mad at me. He initially thought a diode went bad, but it turns out the entire inside was melted and wrecked. He gave me the diode bridge to take home. Its nasty, melted and stinks.
He said something produced a massive draw, to the point of near a dead short and just dried to draw so much power through the alternator it melted.
He asked me if the car overheated - no, temps run 1deg hotter now than before (I flushed the coolant and probably don't have the mix quite exactly the same). He also asked if I have any amps in the car - I don't, its bone stock.
I found a few threads while searching, but nothing specific to my issue.
Before I rip the chassis apart inspecting every square inch of wiring looking for short or break, does anyone have any suggestions for me?
Nothing was obviously loose when I took it apart - all connections I checked (battery, alternator) were good and tight. I figure to check all the common stuff - ground points (could use some guidance on where common ones are - did find the thread about some below a vent and will check those) and the positive cable as much as I can get my hands on.)
The battery was at 11v and showing 50% charge on my charger when I got the car home. I charged it up so it would be topped off before I installed the new alternator. I intend to take it back to AZ and have them test it.
When the alternator died, like the previous one, stuff went haywire inside the car - the radio quit, the trans went into limp mode, the hvac turned off/on/off and blew on high with no display. I just attributed it to the electrical load without the alternator, but maybe that was what blew both alternators and was a cause not a symptom.
My thoughts are -
The other sort of "replace it when you have odd electrical issues" thing which comes up is the key switch. I'm not sure how this would do that, but I guess I can just throw a new one at it if nothing else comes up.
Thanks for any advice/suggestions/assistance you may have.
Scott
I replaced the battery in March of 2012 at approximately 115k miles with one from Autozone.
My alternator went out in August at 119k miles and I replaced it with a rebuilt from a local auto electric shop. All was fine and dandy afterwards. Voltages were in the 13.8 range on the unlocked OBC - not as high as I expected, but were varying as I'd expect so I assume everything was fine.
The alternator went out again in February at 123k miles. I felt like the car wasn't cranking as quickly the past 6-8 weeks, but its been a lot colder and there wasn't anything I could put my finger on, so I didn't really think much about it.
I finally got it back to the rebuilder to be evaluated. He was... mad at me. He initially thought a diode went bad, but it turns out the entire inside was melted and wrecked. He gave me the diode bridge to take home. Its nasty, melted and stinks.
He said something produced a massive draw, to the point of near a dead short and just dried to draw so much power through the alternator it melted.
He asked me if the car overheated - no, temps run 1deg hotter now than before (I flushed the coolant and probably don't have the mix quite exactly the same). He also asked if I have any amps in the car - I don't, its bone stock.
I found a few threads while searching, but nothing specific to my issue.
Before I rip the chassis apart inspecting every square inch of wiring looking for short or break, does anyone have any suggestions for me?
Nothing was obviously loose when I took it apart - all connections I checked (battery, alternator) were good and tight. I figure to check all the common stuff - ground points (could use some guidance on where common ones are - did find the thread about some below a vent and will check those) and the positive cable as much as I can get my hands on.)
The battery was at 11v and showing 50% charge on my charger when I got the car home. I charged it up so it would be topped off before I installed the new alternator. I intend to take it back to AZ and have them test it.
When the alternator died, like the previous one, stuff went haywire inside the car - the radio quit, the trans went into limp mode, the hvac turned off/on/off and blew on high with no display. I just attributed it to the electrical load without the alternator, but maybe that was what blew both alternators and was a cause not a symptom.
My thoughts are -
- Bad chassis ground somewhere (I just need to figure out where they are so I can check them)
- Shorted out jump post on the valve cover (I replaced the plastic surround when I did the VCG last summer)
- Break in the main power wire
- Bad Battery (no idea how/if this would show up, but I'll take it back to be tested)
The other sort of "replace it when you have odd electrical issues" thing which comes up is the key switch. I'm not sure how this would do that, but I guess I can just throw a new one at it if nothing else comes up.
Thanks for any advice/suggestions/assistance you may have.
Scott