71 amp meter trouble
Have a 71 coupe that shows a discharge on the Batt meter when lights are turned on or even the brake lights on. Car has new alternator. There is 13.8 volts at the battery and it goes up to 14.5 when lights turn on. I plugged in another amp gauge and still have problem. I also tried a new battery. So it looks like system is charging properly but gauge is wrong. I am thinking a wire problem any help at this point would be great. Ed
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Re: 71 amp meter trouble
Ed -
The circuitry for the battery gauge (which is really a sensitive voltmeter) on a '71 is exactly the same as the midyears - the black sense wire goes to the battery cable stud on the starter solenoid, and the black/white sense wire goes to the hot buss on the horn relay; the gauge compares the voltage difference between those two points and displays it in terms of current flowing to or from the battery.
With the engine and key off, you should show battery voltage to ground on both of the wires in the gauge connector; if not, the first place I'd look (besides the connections at the starter solenoid and horn relay buss) would be in the multiple connector terminals on the engine side of the fuse block for continuity. -
Re: 71 amp meter trouble
OK thanks for the info I went to the connection at the horn relay and as soon as I touched the wire the amp meter read correctly. Will clean up wires tommorrow and retest but looks like I am on the right path thanks for your help. EdComment
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Re: 71 amp meter trouble
A little caution here... The side terminal of the horn relay acts as the engine compartment B+ buss bar. It's always 'hot', regardless of the ignition switch position.
When you disconnect/reconnect wires here, it's a wise and prudent precaution to DISCONNECT THE BATTERY before you go to work! And, it IS a good idea to take a wire brush and clean the connecting wire terminals, the side bar of the horn relay and the connecting screws/washers to insure/regain a low ohmic contact profile!Comment
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Re: 71 amp meter trouble
One more little piece of trivia while you're at this clean-up task...
The key minder warning buzzer is built into the horn relay. There's only so much useful life in the buzzer and many of us who routinely drive these cars HATE the sound quality of the this warning device...
Sooooo, the black/pink wire that connects to the bottom side of the horn relay (forward most position), is the trigger wire for the key minder buzzer that connects to the steering column. If you pull it and leave it 'hanging', you've neatly defeated the key minder buzzer for peace of mind and horn relay life extention.
Bottom line you can have a 'driver' mode vs. 'judging' mode by simply pulling this lead wire and reconnecting it as needed...Comment
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Re: 71 amp meter trouble
Thanks for the heads up Battery disconnected always when working on my vettes, Wire already hanging, Thanks EdComment
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