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Posted By Discussion Topic: 40 charging question -- page: 1 2     supereal 06-29-2010 @ 10:52 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Most "casual" shorts are the hardest to isolate. As it appears to happen when the ignition switch is off, I'd suspect the two things I mentioned earlier: the horn relay and the lighting breaker. Often, there isn't enough current to sound the horn, but enough to cause the relay to pull, sometimes by a short to ground in the steering wheel to switch leg of the circuit. I always recommend a master cutoff switch for old cars, as the cotton covered rubber insulated wires usually are crumbling and any high resistance connection or short can cause not only a dead battery, but a fire, as well. Sometimes it does seem as though a hex is at work, but you will find the problem. That's why we can it a "hobby"! alanwoodieman 06-29-2010 @ 8:33 AM reply profile send p.m. Senior Posts: 868 Joined: Oct 2009 Superreal, I have been working on the short in my wiring harness and have really found nothing!! The only thing I remotely found was the horn wire connection in the wiring cover on firewall had slipped down the connector but could not really say that was it. Does not light up a test light now and I did find one other problem but it could not have caused the short problem. Thanks to you and all who made suggestions to try and help me. I did accuse my buddy with the 35 of putting a hex on my wagon!! supereal 06-23-2010 @ 9:42 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Tracking down a "casual" short isn't fun, and takes a lot of time. I'd keep isolating each circuit before you replace the wire loom. That is a big job that is often not necessary. We have run into this type of wiring problem when sections have been altered or bypassed, and occasionally a "universal" harness is used and unneeded connections are not removed or insulated. I, too, know the suspicion of "inane animosity of inanimate objects". alanwoodieman 06-22-2010 @ 5:11 PM reply profile send p.m. Senior Posts: 868 Joined: Oct 2009 Superreal, thanks for the diagram,already had several but sometimes it does'nt hurt to have more. I have not been able to work on it again yet. I have the circuit breaker out, the horn reg, voltage reg,brake light switch, starter solenoid, disconnected the feed to the light switch, ign switch, cigar lighter,radio, I will have to remove the radio to get at the wiring for the dome light.I will do that tomorrow. I am begining to think my wagon is MAD at me for working on other flatheads, rewired a 36, fixed wiring in a 35, and am working on the wiring in a 34 got any other ideas short of stripping out the harness and starting over? supereal 06-21-2010 @ 10:16 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Here is the circuit diagram for your '40: supereal 06-21-2010 @ 10:11 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Looking at the wiring diagram, the unswitched connections to the battery include the horn relay, the input to the starter solenoid, the cigar lighter, the input to the lighting circuit breaker, and to the ignition switch. The other connection is to the BAT terminal on the voltage regular, of course. I'd hook up either a test light or a voltmeter between the battery cable and the battery post and disconnect these places, one by one, until you get no reading on the meter. Measuring current is usually beyond the capacity of a non-professional meter. To do that, place a 1 ohm 10 amp resistor in series with the circuit, and put your voltmeter across the resistor. A reading of .02 volts will indicate a .02 amp (20mA)) key off drain, and so forth. You didn't mention whether you have a circuit diagram. I'm guessing either the horn relay or the circuit breaker is "leaking". If the drain ends with the input to the circuit breaker, then the lighting circuit may have a 'casual" short. I'll scan and send a diagram. TomO 06-21-2010 @ 7:52 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 alanwoodieman, Measuring between the battery NEG post and frame will show your battery voltage. If you measure 6 volts or more across the battery and only get 4 volts when measuring to the frame, you have a poor ground connection. To check for a short causing the battery to go dead, connect the COM lead of the meter to the NEG post and use the POS or + lead of the meter to probe. Start by disconnecting the battery from the driver's side of the starter solenoid and probing the 12 gauge wire. If you read voltage with everything turned off and the clock disconnected, you have a short somewhere. Leave your meter hooked up and start disconnecting the brake lights, horn, ignition switch and lights. The brake lights, dome lights and clock are prime suspects when you have a drain on the battery. Tom TomO 06-21-2010 @ 7:33 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 40fordor, the battery gauge shows the voltage in the charging circuit when the car is running. An old, sulfated battery will have a high surface charge causing the voltage regulator to react like the battery was fully charged. The battery gauge would then be on the border line between yellow and green or just into the green. Tom Johns46coupe 06-20-2010 @ 10:54 PM reply profile send p.m. Member Posts: 68 Joined: Apr 2010 alanwoddieman, I had a slight drain as measured by the ammeter on my multimeter (didn't register on the car's ammeter because it was so slight). Chased it to an aftermarket turn signal switch. In this case, I would disconnect everything as close to the battery as possible. Then, with an ammeter, connect one thing and measure. If that's ok, add another and measure. When you find the connection that causes a draw, break that one down and disconnect all of it's branches. Then connect one at a time and measure. Eventually you'll find it. John This message was edited by Johns46coupe on 6-20-10 @ 10:56 PM shogun1940 06-20-2010 @ 8:02 PM reply profile send p.m. Member Posts: 464 Joined: Feb 2010 how about the brake lights going on in the middle of the night,, then find out if its draing through the gen. reg. what else is left This message was edited by shogun1940 on 6-20-10 @ 8:08 PM

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