On Wed, 11 Jun 2008 19:00:05 -0400, "Cleo Frank"
wrote:

Background: 1990 Mazda Protege, very well maintained, very clean
under hood. Last night it started as usual. I drove it to the dumpster
at the edge of my property to dump some trash, stopped the car,
and cut engine. When I tried to start it back up, I got the usual
click of a dead battery; digital clock very dim etc.

Went to NAPA today and bought topnotch battery (the same
kind that came in car when new). I did accidentally install
it backwards (neg lead to pos post and pos lead to neg post),
got some sparks, but the battery is now securely connected.
The lead clamps are pretty clean and don't appear damaged.
But no power whatever, clock dead, nothing.

Ideas?


Do you have a schematic of the electrical system? Connecting the
battery backwards will blow electronic gizmos and some steering
diodes. 1990 is late enough to have an engine computer and that may
be toast.

But check fuses . . . a large fuse on the battery wiring may not look
like a fuse at all (that's another place a schematic comes in handy).
There could be a "fusible link" (piece of wire) designed to blow in
the event of a backwards connection. Sometimes physically close to
the alternator. With the battery in backwards, there's a high current
from the battery through the alternator diodes to ground (they are
forward biased in that case, with nothing but the small resistance of
wiring to limit current). Start there.
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