What is causing fuses to regularly blow out on my daughter's car?

Dear Car Talk

Dear Car Talk | Oct 01, 1997

Dear Tom and Ray:

I have teen-agers, and I try to maintain a small fleet of used cars for them to
drive. My problem with my daughter's '89 Dodge Shadow, however, has left me
several hundred dollars poorer and no closer to a solution. The fuse that
controls all of the dashboard gauges and warning lights has blown eight times
in the two years we have owned the car.

This does not seem to bother my daughter until she runs out of gas, after not
noticing that the fuse is blown again. It bothers me considerably because I'm
constantly having to stop what I'm doing and pick her up. I've taken the car to
several mechanics who have tried to solve the problem. Several have charged me
hours of labor time without finding the cause. One specialized in automotive
electronics, and told me I had a blower motor that was drawing too much power
and causing the fuse to blow. We replaced the blower motor, and ... you guessed
it, the fuse blew again. Any suggestions? -- Patty

RAY: Sure. Get one of those fold-up bicycles and throw it in the trunk of the
'89 Shadow. That way, next time your daughter runs out of gas, she can pedal
home and you can go on with your poker game.

TOM: I'd go back to the automotive electronics guy and politely ask him to
apply the cost of the blower motor to the work he's about to do for you.

RAY: He'll probably argue that you needed the blower motor anyway, because when
he tested it, it was drawing too much current -- and he may be telling the
truth. But that obviously didn't solve your problem. So he needs to get back on
the trail of this short circuit.

TOM: You should ask him to put in a circuit breaker instead of the fuse. Unlike
a fuse, which has to be replaced, the breaker will actually reset itself after
it cools down.

RAY: Then all you have to do is wait. If this is like most short circuits, it
will blow more and more quickly, until it eventually becomes a dead short. A
dead short is one that blows instantly ... as soon as you put in a new fuse (or
one that won't allow the circuit breaker to reset).

TOM: And at that point, your problem will be easy to solve. A dead short is a
breeze to find with a device called a short tester. Even my brother has found
them this way! Good luck, Patty.

* * *

TOM: Hey, do you think you're taking good care of your car? Are you sure?

RAY: If you're like many of our customers, you may be ruining your car without
even knowing it. Yes, even you! Find out how. Send for your copy of our
informative pamphlet, "Ten Ways You May Be Ruining Your Car Without Even
Knowing It!"

TOM: Send $3 and a stamped (55 cents), self-addressed, No.10 envelope to Ruin
No.1, PO Box 6420, Riverton, NJ 08077-6420.

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