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MG MGB Technical - Erratic Guage operation

I have a '69 B roadster that the guages operate irradicaly on. I have driven the car as a daily driver for the last 3 years and 12,000+ miles with no problems. But 2 weeks ago the battery failed in the vehicle for the second time this year. After replacing the battery and starting the car I noticed that none of the guages were working, I jiggled the wires behind the dash and they came back on. they went out once more and the same stradegy solved the problem the second time. However, the problem has become much worse in the last day or so. Whenever the guages go out a set of wires in the back of the dash (the ones that control fuel pump and ignition and plug into the tach) heat up and the radio lights flicker and then go out and the guages follow suit. The problem appears to be heat related since when the car is cool or has sat for a few minutes the guages work for a little while. The car has an electronic ignition system that was installed this year.
Thanks for your input in advance.
Robert

Wires heating up indicates a short, a short can divert so much current that other things further down stream get no voltage. Insuspect you also have bad connections in the brown and white as well, which although normally bad news in this case seems to be limiting the current that can flow and so is not causing your wiring to burst into flames as it could. If it is white wires getting hot you will just have to find out which one and where, since they branch out from close to the switch to a number of circuits. You *could* temporarily fit a 17amp rate in-line fuse in each branch, that would at least tell you which one was shorting if not where.
Paul Hunt

This thread was discussed between 29/10/2002 and 30/10/2002

MG MGB Technical index

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