Dear Financially Strapped (I sound like Dear Abby),
> When I first
> got the car the tach and fuel gauge would operate erratically, working most
> of the time but cutting off completely on occasions. Now they are
> completely shut down along with my rear tail/stop lights, reverse lights,
> and rear side marker lights. I've inspected the fuses (both in the fuse
> box, and the in-line fuses), as well as the wiring, but I can't find any
> exposed wiring, and all of my fuses are fine. Could this possibly be the
> circuitry housed inside of my alternator? Does it sound like my alternator
> needs to be relaced/overhauled?? HELP!!
No, it's not the alternator because an alternator merely keeps the battery
charged and if you were just losing battery charge it would affect all of
the car equally. Aside from the gauges, all of your electrical problems
are in the rear of the car. This makes me suspect that there's something
wrong with your wiring harness. Just because there are no exposed wires
doesn't mean there are no broken wires or dead shorts. It's possible that
the harness broke at some point where it enters the trunk. If wires have
melted and fused causing a dead short, that could explain your sudden loss
of instruments.
A wiring harness is easy and cheap to repair if you have a wiring diagram,
spare wire, and an ohm meter or test light. An ohm meter is better because
you don't need the battery hooked up while checking everything out. With
the ohm meter or test light, determine where electricity is going and compare
this to where the wiring diagram says it should be going. If a wire turns
out to be bad, replace it. If you're getting power where you need it and
something still doesn't work, the component itself probably needs work. MG
light fixtures have a tendency to corrode making them have no ground even
when they have power.
Once the lights have power, then I'd look at the gauges. The gas gauge fix
might be part of the rear light fix because the gas gauge sending unit is
at the back of the car. I'm pretty sure the gas gauge power goes through
the voltage stabilizer behind the dash but I don't know about the tach. I
wouldn't go replacing any electrical components (like the voltage stabilizer)
until wiring problems are either fixed or eliminated as a possibility because
a dead short can roast a new electrical component.
Let us know how it goes.
Denise Thorpe
thorpe@kegs.saic.com
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