Re: [AMC-list] Reversed Battery Connections! What did I do???

[tom jennings <tomj@xxxxxxx>]

On Thu, Sep 17, 2009 at 08:09, <danritz@xxxxxxxxxxx> wrote:
>
>  I'm no expert on this but... I would guess that when the
> battery was incorrectly connected, the ignition key was in the
> "off" position.  If so, wouldn't that alone have prevented
> damage to the majority of the circuitry?


Good point, many accessories should be fine. The stereo etc are probably
fine. Non-electronic gauges would be fine either way.

However the GM ECM is "always on" (tiny trickle to preserve memory contents
and manage crap) and some stereos ahve that too. That stuff is absolutely
not tolerant of reverse polarity.

I doubt the fuel pump and relays are harmed by a momentary reversal --
they're large coils of wire, and not 20-micron-wide aluminum traces in
silicon. Relay noise-protection diodes popped -- if that relay was energized
at reversal time. Likely not.

Likely the ECM fried first, and never energized anything. Most of the junk
that hangs off the ECM (MAP sensor, O2, etc) is powered by the ECM's 5V
supply, which *probably* did not output anything.

Then there's the random small crap no one's thinking of, unfortunately.
Cruise control? I dunno.

It's all a crap shoot, and will need a thorough step by step test. If it was
brief enough, nearly everything could be OK! But something apparently went
SIZZLE and smoked -- let's hope it died protecting things downstream from
it.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://list.amc-list.com/pipermail/amc-list-amc-list.com/attachments/20090917/25f5a81f/attachment.htm>
_______________________________________________
AMC-list mailing list
AMC-list@xxxxxxxxxxxx
http://list.amc-list.com/listinfo.cgi/amc-list-amc-list.com