1979 parasitic drain on battery
01-17-2019, 11:49 PM
#1
1979 parasitic drain on battery
I am experiencing a parasitic drain, it will drain about 20% of the battery overnight. My multimeter is reading about 400 milliamps. When I pull the fuse for the courtesy circuit it drops to 0 milliamps.
So far I have pulled the dome, foot well, glovebox, spare tire lights. No change.
Then I started taking the interior apart again. Cigar lighter disconnected, no change. Pulled aftermarket radio and it dropped 7 milliamps. Non functional power antenna connected to the circuit, pulled and no change. Pulled the dimmer box, no change. finally checked the vanity mirror and the wire was already cut.
If I am reading the schematics correctly, that is everything on that circuit except the clock. I believe the clock (aftermarket quartz) only pulls 4ma. Anyone have any ideas on what else it could be?
So far I have pulled the dome, foot well, glovebox, spare tire lights. No change.
Then I started taking the interior apart again. Cigar lighter disconnected, no change. Pulled aftermarket radio and it dropped 7 milliamps. Non functional power antenna connected to the circuit, pulled and no change. Pulled the dimmer box, no change. finally checked the vanity mirror and the wire was already cut.
If I am reading the schematics correctly, that is everything on that circuit except the clock. I believe the clock (aftermarket quartz) only pulls 4ma. Anyone have any ideas on what else it could be?
01-18-2019, 12:17 AM
#2
Courtesy light timer. Orange relay behind the glove box on the right side.Very common drain.
01-18-2019, 09:25 AM
#8
Instructor
01-18-2019, 09:42 AM
#9
Drifting
Put a battery disconnect switch on and your trouble is gone. C3 Vettes are notorius for battery drain
Last edited by gjohnson; 01-18-2019 at 09:43 AM.
01-18-2019, 12:32 PM
#10
Pro
I had a similar issue
The car would kill the battery in a few days. Disconnect the 2 wire plug at the alternator and it would hold the charge.
It turned out to be the ignition switch.
The car would kill the battery in a few days. Disconnect the 2 wire plug at the alternator and it would hold the charge.
It turned out to be the ignition switch.
Last edited by Fredtoo; 01-18-2019 at 12:33 PM.
01-18-2019, 05:58 PM
#12
Team Owner
My 79 never had a problem with battery drain until I installed aftermarket things like: single wire alternator, digital multispark, digital dizzy...….. I totally agree on the battery disconnect idea. I have the key kind, so it doubles as a antitheft idea.
01-18-2019, 06:48 PM
#13
Le Mans Master
Member Since: Aug 2017
Location: Cool Northern Michigan
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A quick disconnect is a "band-aid fix" for something that is more serious. It needs to be address and repaired. There is no rhyme nor reason to have to completely shut-off the electrical system unless its for long term storage or you live in a bad neighborhood.
04-04-2019, 03:21 PM
#14
Intermediate
Good thread. Thanks! I have had a battery disconnect for a while now. Took the car to someone I thought was reputable and after hours of investigation he said it was the courtesy lighttimer (the orange relay). That didn't work and it drained as usual. I will figure it out one day but until then ...
04-05-2019, 07:08 PM
#15
Drifting
Member Since: Nov 2013
Location: Loud, Raw and Dangerous 1968 327 4S in Southern California
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Good thread. Thanks! I have had a battery disconnect for a while now. Took the car to someone I thought was reputable and after hours of investigation he said it was the courtesy lighttimer (the orange relay). That didn't work and it drained as usual. I will figure it out one day but until then ...
Good luck!
Redvette2