71 current draw
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Intermediate
Joined: Mar 2009
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From: Draper Utah
71 current draw
My 1971 454 auto has a current draw that slowly discharges the battery when the car sits for a day or so. What are the common places to look first? I did a search and only found for 1980.
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Current Draw!
Try disconnecting the battery pos cable and put a test light between the cable and the battery, then pull 1 fuse at a time untill the light goes out. When the light goes out you have to trouble shoot that circuit. If you pull all the fuses and the light stays on then disconnect the pos from the alternator, you may have a bad diode. PG.
Racer
Joined: Feb 2009
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From: San Diego CA
Try disconnecting the battery pos cable and put a test light between the cable and the battery, then pull 1 fuse at a time untill the light goes out. When the light goes out you have to trouble shoot that circuit. If you pull all the fuses and the light stays on then disconnect the pos from the alternator, you may have a bad diode. PG.
You're isolating one circuit at a time while checking for current draw. 
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Gotta dig deeper!
Next your going to have to check the unfused circuits. Stellar asked a good question, did you add anything like a new radio? Do the hazard lights work OK? Has the horn been working properly? Do the parking lights and headlights work OK? Is the starter or solenoid causing the problem? Do you have a power antenna? You have to go through each system step be step.
PG.
PG.
Safety Car
Joined: Sep 2007
Posts: 4,443
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From: Indy Indiana
how about your your alternator 2 wire plug, pull that and test your light.. also, your radio presets and clock will pull some current with the car sitting... you will need to get a milliamp tester and let us know what the draw is, make sure lights are off, key out, door closed.. 10-20 milliamp draw is ok, but 1000 milliamp draw is not.. if you pulled your fuses out and still have problem, then check your battery, it may just be old and time to replace.. else you have an unfused direct path to ground. any unfused direct path to ground should fry your harness and drain your battery in an hour.. so I doubt that is your problem.
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Burning Brakes
Joined: Jun 2008
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From: Michigan
The threaded post on the horn relay is hot all the time and has no fuse. It is protected by a fusible link.
With the test mentioned above start with the horn wires and then remove the wires connected to the horn relay stud and see if that is where the drain is.
With the test mentioned above start with the horn wires and then remove the wires connected to the horn relay stud and see if that is where the drain is.
Drifting
Joined: Aug 2005
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From: League City TX
In a Vette though, accidental arcing is less likely than in "normal" cars.
Racer
Joined: Apr 2006
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From: Warrensburg MO
Thread Starter
Intermediate
Joined: Mar 2009
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From: Draper Utah
The car is new to me. It is a completely stock 71 454 AM/FM radio and NO power antena. Last night I fixed all the exterior lights (parking, headlight and turn signal). The headlight switch was bad too, so I replaced that. Now all the lights work appropriately.
The horn does not work.
The battery and starter are new from Napa, but it has the original GM alternator.
How do you test the alt. 2-wire plug?
To test the milliamp draw do you just disconnect the pos. battery terminal and connect the milliamp gauge to the battery and cable end?
Thanks everyone for your suggestions.
The horn does not work.
The battery and starter are new from Napa, but it has the original GM alternator.
How do you test the alt. 2-wire plug?
To test the milliamp draw do you just disconnect the pos. battery terminal and connect the milliamp gauge to the battery and cable end?
Thanks everyone for your suggestions.
Le Mans Master
Joined: Jan 2006
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From: Boca Raton Florida
Use an amp meter instead of the test light as mentioned above to determine exactly what the draw is in miliamps. You can do this at the battery, ot at the alternator. The shop manual details how to test the alternator with an ohm meter, been a while so I won't try to explain it now. To determine if the alternator is causing the draw, unplug the 2 wire connector and disconnect the big red wire off the back, that will completely remove the alternator from the system.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Not Fixed Yet!
You removed all the fuses and disconnected the big wire on the alternator and the test light is still on, now unplug the 2 wire connector from the alternator, if the light goes out the problem is in the alternator.
You say there is a new starter. On the wiper motor there is a 3 plug connector and a seperate black ground wire, the other end of the wiper motor ground wire goes to a bolt that holds the starter on. The end of that black wire has a large lug and by mistake it gets attached the the starter pos wire, make sure that wire is on the starter bolt or on a bellhousing bolt.
I have a troubleshooting guide for the horn, I think it was published by Jim Shea but I don't have the link to it but if you need it pm me your email. PG.
You say there is a new starter. On the wiper motor there is a 3 plug connector and a seperate black ground wire, the other end of the wiper motor ground wire goes to a bolt that holds the starter on. The end of that black wire has a large lug and by mistake it gets attached the the starter pos wire, make sure that wire is on the starter bolt or on a bellhousing bolt.
I have a troubleshooting guide for the horn, I think it was published by Jim Shea but I don't have the link to it but if you need it pm me your email. PG.
Thread Starter
Intermediate
Joined: Mar 2009
Posts: 25
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From: Draper Utah
I had the starter off a couple weeks ago and Im pretty sure that black wire isnt where you say it should be. I'll have to jack the car up and check again.
I seems as though after fixing all the exterior lights the other night I fixed the problem. My milliamp draw is only 13mA. I also replaced the headlight switch. Before to get the interior lights to work I had to wiggle the headlight switch ****.
I seems as though after fixing all the exterior lights the other night I fixed the problem. My milliamp draw is only 13mA. I also replaced the headlight switch. Before to get the interior lights to work I had to wiggle the headlight switch ****.
Burning Brakes
Joined: Jul 2008
Posts: 923
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From: Green Bay Wisconsin
Try disconnecting the battery pos cable and put a test light between the cable and the battery, then pull 1 fuse at a time untill the light goes out. When the light goes out you have to trouble shoot that circuit. If you pull all the fuses and the light stays on then disconnect the pos from the alternator, you may have a bad diode. PG.
Douglas in Green Bay
