Parsitic Load
Thread Starter
Instructor
Joined: Sep 2004
Posts: 206
Likes: 0
From: Columbia MD
Parsitic Load
One of the many issues I found with my 68 convertible since purchasing her 4 weeks ago is a parasitic load on the battery when the key is out of the ignition.
I installed a kill switch to allow me some time to figure it out. Not sure if the car had the issue when I bought it, but it did show up just a few days later. With the key out of the ignition, I am measuring 2.4-2.5A from the battery. I installed a new battery so that should not be the issue.
I removed all the fuses with no change.
Today I started looking under the hood. I found that if I disconnect the two-prong plastic connector from the relay terminal of the alternator, the draw drops to 600 mA. If I plug it back in and remove the harness from the voltage regulator, the pull drops to 0 mA.
Question: Do I need a new voltage regulator? Further testing? Any advice would be greatly appreciated for this novice mechanic!
Chris
I installed a kill switch to allow me some time to figure it out. Not sure if the car had the issue when I bought it, but it did show up just a few days later. With the key out of the ignition, I am measuring 2.4-2.5A from the battery. I installed a new battery so that should not be the issue.
I removed all the fuses with no change.
Today I started looking under the hood. I found that if I disconnect the two-prong plastic connector from the relay terminal of the alternator, the draw drops to 600 mA. If I plug it back in and remove the harness from the voltage regulator, the pull drops to 0 mA.
Question: Do I need a new voltage regulator? Further testing? Any advice would be greatly appreciated for this novice mechanic!
Chris
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Most likely you are looking at a relay problem (68 was the last year for an external mechanical regulator). The draw sounds about right for the alternator exciter current being stuck closed.
While it would cost only around $25 or so for a replacement regulator to confirm, I'm not a big fan of throwing money at a problem until it goes away. I suggest you Google: "how to test voltage regulator" to confirm a suspicion.
While it would cost only around $25 or so for a replacement regulator to confirm, I'm not a big fan of throwing money at a problem until it goes away. I suggest you Google: "how to test voltage regulator" to confirm a suspicion.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
That would have been my first question too.. Do the wipers on your car work... If they do not, go to the wiper motor and un-plug it to see if the draw goes away. If it does... post back.
Lets say the wiper actuator isn't working and you turn on the wiper switch. On a 68, the motor will try to run... but it can't because it is missing the ground for the motor created when the wiper door linkage depress's the limit switch... So it goes looking for a ground and creates the draw.
Willcox
Lets say the wiper actuator isn't working and you turn on the wiper switch. On a 68, the motor will try to run... but it can't because it is missing the ground for the motor created when the wiper door linkage depress's the limit switch... So it goes looking for a ground and creates the draw.
Willcox
Thread Starter
Instructor
Joined: Sep 2004
Posts: 206
Likes: 0
From: Columbia MD
Yes, the wipers do work. However I do know that the previous owner received the car with non-working wipers. That was one of his projects. Could the wiper motor still be the problem, even if it is functioning?
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Unplug it and see if the draw goes away.. two connectors both have three wires. One is on the motor, one is off the motor.
Go to this link and it will show you the wires that make the motor run.
http://willcoxcorvette.com/repairand...lp.php?hID=329
If the draw is still there, then I'd scroll up and us the suggestions above. It was just a hunch I had..
Go to this link and it will show you the wires that make the motor run.
http://willcoxcorvette.com/repairand...lp.php?hID=329
If the draw is still there, then I'd scroll up and us the suggestions above. It was just a hunch I had..
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Thread Starter
Instructor
Joined: Sep 2004
Posts: 206
Likes: 0
From: Columbia MD
Unplug it and see if the draw goes away.. two connectors both have three wires. One is on the motor, one is off the motor.
Go to this link and it will show you the wires that make the motor run.
http://willcoxcorvette.com/repairand...lp.php?hID=329
If the draw is still there, then I'd scroll up and us the suggestions above. It was just a hunch I had..
Go to this link and it will show you the wires that make the motor run.
http://willcoxcorvette.com/repairand...lp.php?hID=329
If the draw is still there, then I'd scroll up and us the suggestions above. It was just a hunch I had..
I also purchased a new voltage regulator and verified that is not the cause. The alternator outputs 14.4 V with the engine at 1500-2000 rpm and fully loaded. I only measured a few mv of AC ripple across the alternator so I am not convinced that is the problem. When I disconnect the alternator completely, I still have a 700 mA draw.