HELP: '91 MR2 electrical problem

My '91 MR2T's got an intermittent electrical problem that I could use
some help troubleshooting. Given the symptoms, I'd think it would be
fairly easy to track down:

The entire system goes dead - no lights, no ignition, no dash, no
radio, no clock, no hazards. It's happened twice so far (within a 5
minute span) the car has been at idle and then again at high RPMs. It
appears that slamming a door or hood or pushing the car over a bump
will bring it back.
When the electrical power dies, the tach goes haywire for a few
moments (although the engine doesn't seem to race or stutter). When it
comes back, it's at full strength (starts back up just fine, stereo
blaring, lights on) with no warning lights or anything.
If this were a power- right? So it must be a break rather than short. Where could the
electrical system suffer a break that would deaden the entire car,
even while running? Would a break at the battery take out the entire
system?
I just had some stereo work done 2 days prior, so someone was in
behind the dashboard. Would there be a single line (or plug?) in the
under-dash fuse block that would do all this if loose?

Any and all help would be appreciated!

It was just adding a changer (which plugs entirely into the head
unit), so they wouldn't have done any re-wiring. I was thinking more
in terms of nudging something loose.

Nope. It's got the factory MR2 alarm. I didn't think of that though,
does the factory alarm have an ignition kill? It would have gone off
if it were activated and not nuked the radio/lights circuits though,
right?

<snip>

If this started after the install, then it's obviously a problem created by
so. Without knowing what you had installed (and where they should've
tapped - or may have tapped - wiring), I would suggest you take it back to
who installed your equipment and explain the problem. Explain the problem,
and either have them fix it or have them pay for you to bring it somewhere
to have it fixed.

I'm sure we could route and isolate the problem, but if it is related to the
install, then they are liable and they should be responsible.

--Applejax

[Don't hit reply, blah blah blah, use ]
http://www.jersey.net/~applejax

I had a similar problem with our '91, which fortunately I did not have
a problem diagnosing.

I was already aware that someone had borrowed/stolen the battery hold-
down bar, so when it refused to start, all I had to do was remove the
spare and wiggle the battery connections. Presto!

This never happened while driving, but I did have to do this two or
three times in a week while waiting for a new bar.

I would check the terminals, and make sure the bar is holding the battery
nice and tight first.

--
D a v i d H i l l m a n
nma, scca, scscc, aroc, imoc

That was exactly the problem. When Sears replaced the battery a year
ago, they never replaced the hold-down bar. As a result of the battery
floating around it's tray, one of the leads developed a break in it.
the next question is - what the heck is the lead for? It's a blue lead
that's bolted on to the + battery connector. I can't find it anywhere
on the electrical manuals, they all list the battery leads as white.
It's not the main lead either.

That sounds like one of the installers leads. Blue is frequently used by the
aftermarket as the full-time power lead or remote lead.

Glad you found it. These guys get pretty sloppy sometimes. I guess they have to
work fast to make money, but you would think that they'll probably just get the
car back in a few days because they screwed something up, so what was the sense
in not taking the time to do it right the first time?

[ missing battery hold-down bar ]

Do you have an aftermarket alarm with an ignition lock?

--
D a v i d H i l l m a n
nma, scca, scscc, aroc, imoc