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Classic/Antique Car Repair/Auto electric short circuit


QUESTION: My question is concerning a possibility of a short circuit in the auto electrical system and is quite general in nature. The ignition key gets slightly more than warm when in use. I have replaced the barrel which incidentally is a plastic casing. It is connected to the car wiring harness via a 5-terminal female socket. The insulation of the wires and the socket have melted to an extent but still seems usable. This is the second barrel I have replaced. I am thinking of replacing the socket just in case it helps to reduce any resistance. How do I check for any possible shorting in the circuit.

ANSWER: I have several questions. What is the year make and model of the car? Next, what accessories do you have in the car such as A/C, sound system with an amp, or any other accessory that is switched through the ignition switch? High current draw through the ignition switch will cause the heat as well as a defect in the switch or the connector causing resistance. Please let me know and then we can figure out a cure.

---------- FOLLOW-UP ----------

QUESTION: The car is actually a 2005 Daihatsu MIRA 660 cc derivative in Malaysian guise.
Accessories include an air-conditioner and radio/CD player only.
The problem occured only about 6 months ago.

I don't think that I have even seen one of those much less worked on one. However that said I think that I would start checked amperage loads on the system. Do you have a digital multi meter and if so what brand and model? It is possible that the A/C compressor clutch or the blower motor may be developing an internal short that is increasing the amperage draw and placing a load on the ignition switch, so let me know about what kind of meter that you are using and we will go from there.

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Brad Sears


All automotive including antique and collectible. However if the car has been modified I can only answer in general terms and maybe get you pointed in the right direction.


Automotive tech instructor. Syndicated auto columnist 1970's though the early 1990's. Syndicated auto radio talk show, Ask Brad About cars, CBS Radio 70's through 90's TV Show "Last Chance Garage" 1980's PBS-TV syndicated. Auto instructor for the following companies: Fram Autolyte Holly Carter AMF Ford Motor University Of Conn Blue Hills Technical School Sugar River Technical Center Grew up in a family garage in Needham Mass and turned wrenches from the age of 14.

Manchester Union Leader, Nashua Telegraph, Motor Service Magazine, Yankee Magazine, Popular Mechanics (Saturday Mechanic early 80's), Los Angeles Times, New York Times, and lots more.

More than I care to remember. Basically Franklin Technical Institute in Boston, Northeastern University, Fitchburg State Teachers College, Tufts University, and a lot of factory schools along the way.

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Moto Award winner. And much more.

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