Parasitic Draw On Battery

[Rayzen]

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 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.*

[Blue Bowtie]

The next points of isolation would be the fusible links. One of those should isolate the current draw, unless the alternator itself has a failing rectifier or leaky filter capacitor.

[ctesla]

Rayzen, welcome to Automotive Forums..
Blue Bowtie took my first guess; fusible links and alt. rectifier..
but if that Chevy Van is still set up as RV, you might have a 12V/110V
fuse box/circuit panel under furnace, or fridge?? might look, as your rig/truck
might not be the draw; but the house.. many RV fridges' can run 110V/12V/ and sometimes even propane.. also a hot dome light/zone light in the back might be
hot; or even the entertainment center..
but then your ideas is also valid: if she's been stored since winter, and your breaking
it out of mothballs now, a packrat might have snacked on a power or ground lead underneath..
good luck..

[ctesla]

ALSO- forgot in post, but if you have added an aftermarket LED/LCD monitor for any of your battery and power items in RV, if it is not on a toggle, this could be constant drain, as they usually stay illuminated, and use about .5-2.5amps and .01-.05V depending upon gauge and length of wire..

[Rayzen]

Thanks, guys, for all of your time and help.

I have made some progress by following your recommendation of checking the alternator. When I unplug the alternator, the meter drops way down, but not all the way.

But now that makes me afraid to buy a new alternator, as I don't want to install it without knowing why the original diodes died in the first place. I have read where people have burned out several new alternators in a row.

The thought of doing that with the idea that there still might be something else wrong is pretty intimidating.

So, I have several questions that it would be nice to know from those of you who have more knowledge than me (not saying much, as I know next to nothing about automotive electrical matters):

1. What caused the alternator diodes to blow? (just plain old age?) Maybe something I did?
2. The cable coming out of the alternator appears to have some kind of gunk inside the connector. Is that something that should be there? If so, what is it for? If not, would that have blown the diodes?
3. 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?

[Blue Bowtie]

On an early '80s G-van that last number is probably the circuit number. It may or may not be related to a terminal on the bulkhead connector.

Also, GM is fairly consistent in its wiring schemes. PNK/BLK is commonly used for the 12V supply from the ECM/Engine Control circuits. This is routed to things like the ECM, spark control module, EGR solenoid, EVAP solenoid valve, speed sensor, distributor power, instrument cluster, and numerous other loads.

Failure of an alternator rectifier can result from inappropriate jumper cable connection, battery shorts, severe overload, connection of a faulty battery charger, poor heat sink connection or inadequate alternator cooling, or sometimes just cumulative damage and age.

Typical parasitic draw on an early CCC vehicle with the 8-bit ECM is around 35-50mA. The variations in radios and other accessory equipment can increase that slightly.

[Rayzen]

Thanks for your reply, Blue Bowtie.

I put the new alternator in, today, and there is now no parasitic drain. The alternator is working fine, putting out 14+ v.d.c., so I'm breathing a lot easier.

The only remaining problem is figuring out where that pink/black wire goes. I notice that the instrument cluster is dead, so, as you said, that must be what the wire is for. If I only knew where it is on the fuse block, that would be great, but I can't see any label on that block which comes close to saying something like 'Instruments' or 'dashboard.' Additionally, even if I can see them, about three of those labels are rather cryptic.

I don't know what a circuit number actually denotes in terms of practical use, as opposed to the usefulness of knowing a connector pin number or fuse block number. I'm afraid of just sticking that wire into any old 12vdc circuit, for fear of blowing a fuse or ruining some electrical component.

That fuse block is in such an awkward place that it's really hard to see or do anything in there. You have to lie upside down (on your back), it's dark, and there is zero room to even squeeze you arm up into a small, crowded space, complete with wires hanging down in front of the block. All of that makes it very difficult to read the labels that are next to most fuses, relays, or connectors. The newer vehicles with the fuse block in the open, under the hood, are so much nicer.

[ctesla]

sorry for delay.. been scouring docs, trying to find anything 80s; something close to truck/rv platform; i got nothing..
Blue Bowtie is right though.. that pink/black goes to dash/inst/gauges..
and i did dig up my diagram from my el camino (pre-obd1), but still, Generalized Motors used same color/resistance of wire:

https://drive.google.com/file/d/1eaL...ew?usp=sharing

(hope i did that right) first time converting pdf into google doc/drive..
it shows the .8 resistance pnk/blk wire travelling from 20amp block to most of dash
number in square is wiring harness block#.(39)

and i do not know on your RV, but my 77 G20 had a bolt dead center in fuse block (3/8"?. maybe 7mm?), and when taken out, my fuse assembly swung out and down and away from firewall on plastic hinges that allowed me to better 'play' with it; instead of upside down, back contorted, eyes crossed, etc..
hope this helps..

[Blue Bowtie]

There may be a fuse marked "GAUGE" with adjacent spade terminals marked "IGN" which are often the pink/black connections.

[Rayzen]

Originally Posted by ctesla

sorry for delay.. been scouring docs, trying to find anything 80s; something close to truck/rv platform; i got nothing..
Blue Bowtie is right though.. that pink/black goes to dash/inst/gauges..
and i did dig up my diagram from my el camino (pre-obd1), but still, Generalized Motors used same color/resistance of wire:

https://drive.google.com/file/d/1eaL...ew?usp=sharing

(hope i did that right) first time converting pdf into google doc/drive..
it shows the .8 resistance pnk/blk wire travelling from 20amp block to most of dash
number in square is wiring harness block#.(39)


and i do not know on your RV, but my 77 G20 had a bolt dead center in fuse block (3/8"?. maybe 7mm?), and when taken out, my fuse assembly swung out and down and away from firewall on plastic hinges that allowed me to better 'play' with it; instead of upside down, back contorted, eyes crossed, etc..
hope this helps..

Thanks for all of your time and effort, 'ctesla,' I really do appreciate it. These online forums and the helpful people on them, like you and 'Blue Bow Tie,' are gold mines for people like me, who don't really know what they're doing. I'm just guesstimating, but after looking online and taking an average of $112/hr. for a mechanic's fee, and figuring about a guess of 1 1/2 hr.s to find the original problem (shorted diodes in alternator), then an hour, each for taking the old alternator off and putting on the new one, you guys have saved me about $400. I definitely owe you guys a beer!

I will go out there and see if there's a bolt that will allow me to actually see that fuse block more easily; if so, that would be a real help.