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Rayzen
Novice
Apr 19, 2021, 8:47 PM
Post #1 of 10
(2308 views)
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Parasitic Battery Drain
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I have an old 1984 V-8 Chevy van (G30) underneath a Lindy class C RV. The problem is that there is something sucking my battery at the rate of 3 amps and I can't find the source of that drain. I have done the usual method of trying to find such a drain: hooking my meter in series with the battery's negative post and chassis ground, then pulling the fuses, one at a time, hoping to see the meter drop to zero, but I've pulled every single one of them and the meter continues to show 3 amps flowing. The battery is brand new. The Haines manual states that there is only one fuse block, which is under the dashboard, next to the driver's left knee. If there is another fuse block somewhere, I don't know where that is.
Obviously, I have made sure that there are no lights on anywhere inside & outside, the key is off, all doors are shut, all fans and other motors turned off, etc., so there should be zero current being drawn from that battery. I can only conclude that there must be some kind of a harness short to ground somewhere, but then I'm certainly no auto electrician, so I am probably missing something.
What can I do next to find the problem?
In trying to find the problem, I have looked in my Haines 1968-1992 Automotive Repair Manual, but I see that the fuse block picture does not match mine, so I'm now going to see if I can find something online. If anyone would have a good link, I would sure appreciate seeing it.
However, of more concern than finding the right fuse block picture, I would really appreciate hearing any tips as to just how I should proceed with troubleshooting the system to find the source of the current drain.
All of the external lights (headlights, turn signals, backup lights, brake lights, emergency flashers, parking lights) work fine, as well as the windshield wipers. The engine starts and runs fine.
Any help would be very much appreciated.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 19, 2021, 11:25 PM
Post #2 of 10
(2298 views)
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Re: Parasitic Battery Drain
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At least it's an '84 to have some chances with probably little or no help from the coach maker now?
Of course that's too much drain - a lot too much.
Once again some maybe things to try based on what still has power when fuses pulled. You've done what most would do finding nothing I do my best with what's still empowered without the coach items and an area that one failed about that model year - I just plain lucked out.
* Does starter motor's solenoid (on top of it) fully retract? Are wires there clean and at least look OK. When you do get it to start does it sound normal once running meaning starter quits right away?
> Off that just because you could unhook all the back items the starter can keep drawing and not have enough to be too obvious. I'd test that if it's a draw right to it if some power is still going to starter when nothing is being triggered for it.
> Another is alternator? Unhook the thing they can short inside! Careful it's tight there do that without battery connected so tools don't really short out.
> Another is the firewall side of fuse block inside? That should come apart is before fuses all greased up with spade terminals. I've seen and fixed one that did the opposite of drain it didn't provide power to inside fuses that thing was all lacking grease from original being messed with (my guess at the time) to power stuff inside that it wouldn't supply if not a decked out still a van's sheet metal but not a coach maker from GM. That was obvious with heat had harmed terminals in the greasy mess did not have enough grease left wasn't near this old but close to this model year. It takes grease that doesn't conduct electricity at that block if that's it use electric grease (Silicone based) and I'd test the grease with a sample for ohms that it draws nothing on a piece of wood prove it's the right stuff.
Those are the things that come to mind that have power if you know of more under-hood check it.
Good luck, it would be a good time for this thing to run about now without this problem,
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 20, 2021, 3:53 AM
Post #3 of 10
(2287 views)
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Re: Parasitic Battery Drain
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3 amps is a big drain
I'll give you a second vote on the alternator. That's fairly common.
Also being that it is an RV, there could be any type of aftermarket accessory added to the system that could be relying on a large fusible link that instead of small fuse that you have not been disconnecting. Give a second look for any sort of pump, lighting or other system that was not part of the original van.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Apr 20, 2021, 3:53 AM)
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Rayzen
Novice
Apr 25, 2021, 11:38 AM
Post #4 of 10
(2194 views)
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Re: Parasitic Battery Drain
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3 amps is a big drain
I'll give you a second vote on the alternator. That's fairly common.
Also being that it is an RV, there could be any type of aftermarket accessory added to the system that could be relying on a large fusible link that instead of small fuse that you have not been disconnecting. Give a second look for any sort of pump, lighting or other system that was not part of the original van. Thanks, guys, for your helpful responses. You both were right: the problem was shorted diodes in the alternator. After I unplugged the alternator, the drain disappeared. So, I went to NAPA, got a new alternator, installed it, and everything's looking great. No drain. However, now I have a new problem which is entirely my own fault. As stated earlier, when trying to find the source of the parasitic draw, I was unplugging things from my fuse block one at a time; however, I accidentally snagged and unplugged a pink wire with a black tracer on it and now I don't know where it goes. So, when I look at the electrical wiring diagram in the Haynes Automotive Repair Manual, it shows the pnk/blk wire on several pages, designating it with something like '.8 pnk/blk-39.' I am wondering about that final number, '39'. Does this number stand for a pin on a connector or the position on the fuse block where it should be inserted? It is so dark and cramped underneath that dashboard that I can barely see what I'm doing, lying upside down with wires hanging down in the way. There is barely enough room to stick my arm up in there, let alone read the fuse location...some of which are cryptic.
(This post was edited by Rayzen on Apr 25, 2021, 11:47 AM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 25, 2021, 11:51 AM
Post #5 of 10
(2190 views)
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Re: Parasitic Battery Drain
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Of course an RV if any toys has it's own power either direct or fused. That isn't known it is or was available from the coach maker no telling a hidden piece of plywood some of few I've messed with was butchery IMO. Hand made stuff of low production hope you have info on it if needed,
T
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 25, 2021, 11:56 AM
Post #7 of 10
(2184 views)
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Re: Parasitic Battery Drain
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I didn't see your edit when I posted. Let me/us think about that. Glad you found alternator had a fault now on to this,
T
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Rayzen
Novice
Apr 25, 2021, 4:40 PM
Post #9 of 10
(2154 views)
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Re: Parasitic Battery Drain
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Does this number stand for a pin on a connector or the position on the fuse block where it should be inserted? Post that diagram you talk about and I'll tell you what it means.
Okay, here's pic of that wiring diagram. I had a heck of a time trying to figure out how to attach a photo, so that's why I'm so late in replying: http://autoforums.carjunky.com/photos/pic/5936SMC2/1754.jpg
I hope this works and that you can see it okay!
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 25, 2021, 4:44 PM
Post #10 of 10
(2150 views)
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Re: Parasitic Battery Drain
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That's makes it pretty clear where it goes. The other end goes to the dash cluster.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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