Would appreciate any suggestions for finding the likely source of a short circuit that is causing the battery in my '64 to drain dead, with the engine off, in a matter of hours. I've confirmed that the battery and charging system (alternator) are fine (brand new in fact). This is confirmed by my being able to start the car no problem after driving the car even short distances. I've even disconnected the clock and radio in case either of these was the problem.
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Re: Short Circuit in '64
Hey Ray,
Too keep yourself from chasing your tail- You need to make SURE the system is charging. The battery will hold a charge after a short drive enough to start, doesn't necessarilly mean the system IS charging. If you have a voltmeter- check and make sure when the car is running (at idle- nothing on) you see atleast 13.5 volts across the battery. If you don't have a meter, an easy check is to disconnect the battery while the car is running. If it stalls - the system is not charging.
You didn't say what the ammeter is doing.
When did this problem start? ( or not start!)
Richard -
Re: Short Circuit in '64
looking for the short is logical detective work. you'll need a cheap volt/ohm meter, either digital or analog. these are $20 or less, anywhere. you will also need the correct wiring diagram form the factory manual for your car.
after that it is a matter of isolating the circuit that is the culprit. you should disconnect the fuses, one at a time. what i mean is, pull a fuse and let car sit overnite. if you still have a short, then replace it and pull another one. enevtually, you ought to find the offending circuit. when you do, then study the wiring diagram. disconnecdt the parts of the circuit, step by step. everytime you disconnect somthing [like the tail lights], let cart sit overnite. at some point you ought to be able to identify the wire that is the problem. the volt/ohm meter willa llow you to see which indivual wires ahve infinite resistance [no short] and which ones have twelve volts where it ought to be. follow the electricity from the battery to ground on the diagram to see where 12 volts ought to be.
another approach is to disconnect the wire connector tht sits near the clutch. i think this will separate the front of the car from the rear, electrically.
i think you get the idea. selective disconnection.
i have had a number of old rusty sports cars, including three english cars with lucas systems [the prince of darkness]. although it is time consuming to find a short, it is do-able, and MUCH cheaper [like hundreds] than going to a shop. also, repairs cost about 50 cents if you are lucky.
good luck, wernerComment
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Re: Short Circuit in '64
First, there are competent auto electric shops out there with the skill, tools, and knowlege to troubleshoot for you. BUT, if you want to undertake the task yourself, here's the basic proceedure.
First, some branch circuits in the car are switched (ignition switch) while others are unswitched. And, some circuits and/or circuit paths are fused while others are unfused. Know which is which and where they 'live'....
Fault isolate the switched vs. unswitched circuits by disconnecting the wiring harness from your ignition switch. If the problem goes away, you've learned the short 'lives' in a switched branch circuit.
Fault isolate fused vs. un-fused circuits by removing all the fuses from your fuse block, miscellaneous in-line aux fuse block fuses and don't forget the branch circuits that are protected by circuit breakers (disconnect or open circuit each circuit breaker). Now, re-connect each circuit breaker and/or fuse, one at a time, until you re-create the excess drain. That's where your problem lies--go find it/fix it!
If the above fails to point to a telltale branch circuit, it's time to start looking at the inobvious, unswitched & unfused circuits, and consider things like a leaking diode in the rectifier bridge of your alternator EVENTHOUGH you've just replaced or had the alternator 'restored/rebuilt'....Comment
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Re: Short Circuit in '64
Terms, If you really had a short, you would know it instantly. If it was in a fused circuit the fuse would go immediately. If it was in an unfused circuit, you would be grabbing a fire extinguisher. What you have is a device that is on or has failed in some way as to draw current. Jack`s method is a good one to isolate the area. On midyears the most common fault that causes such a condition is the clock or the alternator.Comment
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Re: Short Circuit in '64
Fifteen years ago, I may not have been patient enough or smart enough to trace down the short I had. I basically lived with a slow short that drained the battery in a few days by disconnecting the battery if it was going to be parked several hours. My '61 had been converted to an alternator, and over a couple of years, I went through several alternators, regulators and batteries. It paid to have lifetime warranties on the regulator and alternator. However, after three batteries under warranty, Sears said it would no longer warrant a battery for that car. It always checked out OK on the tests they ran, and the local battery and electric shop could not find the short. I broke down and bought a new wiring harness and returned it to a generator. No problems since.Comment
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Re: Short Circuit in '64
Had a similar problem in my '63, turned out to be the glove box light was staying with the door closed. Sat in the car in the pitch dark to find it.
KenComment
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