Parasitic Draw - locating.

[Rein]

(Didn't see a forum section on Electrical, so I hope posting this here is OK.)

2004 Chevy Astro 100K 4.3L

-I have a parasitic draw of .300mA.
-tested every fuse under hood and driver’s side fuse blocks and they’re all zero.

Is there a third fuse block somewhere else? If not, is there any other method to locate the draw?

As far as I know there are no aftermarket gadgets wired into this van. Is there anything in this van that came out of the factory without being fused?

[MountainManJoe]

(Didn't see a forum section on Electrical, so I hope posting this here is OK.)

topic moved to electrical section

-I have a parasitic draw of .300mA.

3 tenths of a milliamp is bugger all.
Did you mean 0.3A (300mA) ?

Is there a third fuse block somewhere else?

Not that I'm aware of.

If not, is there any other method to locate the draw?

this video is pretty good

Is there anything in this van that came out of the factory without being fused?

alternator, starter, or sometimes even a battery with a bad cell can self discharge.

[Rein]

Sorry, Joe - I think because you moved my post I wasn't receiving notifications. Anyhow, yes, you're correct - I wrote that number incorrectly - it was 300 milliamps (0.3A / 300mA). I'm a total electrical idiot. ;-)

Since it's very labor-intensive to remove the alternator to disconnect it from there, will it work to disconnect the large positive cable off the battery instead? Also the smaller red cable going to the underhood fuse/relay block? One or the other or both? I've got the negative lead and battery post set up in series with my DVOM set on 10A so I should be able to see if it's the alternator that's the draw if I disconnect the battery positive cable, right?

Never heard of a battery self discharging, but how would I test for that, just disconnect it from the vehicle completely connect both leads of my meter to the posts and watch the DC drop over time?

Sorry if this makes no sense - I'm kind of scratching around in the dark since electrical is my weakest area

[MountainManJoe]

I think because you moved my post I wasn't receiving notifications.

Notifications are off by default, so either turn it manually for the topic using the wrench icon, or change your preferences in the user control panel.
Moving topics should not affect notifications.

I should be able to see if it's the alternator that's the draw if I disconnect the battery positive cable, right?

Set up your meter exactly as the gentleman does in the video I posted.
Disconnect the alternator, and see if the current changes.

Never heard of a battery self discharging, but how would I test for that

It's real. A car battery is composed of six 2.1V cells. One or more cells can short out internally.
Well step one is to measure the voltage of the battery (battery should be charged up and left to sit a few hrs to equalize). Then measure it again under load (engine off key to to 'run', but turn on a bunch of accessories like headlights, dome lights, blower, etc.). Ideally you take your van to have the charging system load tested. Most auto part stores (Autozone, Advance, Oreilly, etc.) do this test as a free courtesy, but the part jockeys aren't terribly knowledgeable. The best thing is to take it to a battery dealer and they'll hook up a fancy carbon pile tester and they usually know their craft.

[Rein]

Thanks so much for answering most of my questions!

The wrench icon doesn't have any options that you describe. In my user control panel my default option "Notify me upon replies by default:" was already turned on but I'm still not getting notifications. I the button just to see if anything changes.

I disconnected the positive battery terminal and the draw disappeared. Now what, in order or ease of execution?

I have a Topdon battery load tester. I'll attach the reading I just got. Sorry, I don't know how to rotate it. ;-)

[Rein]

(This is a followup post from my previous one - hoping more people see it and will chime in.)

2004 Chevy Astro 100K 4.3L
-I have a parasitic draw of .3A/300mA.
I’ve tested all fuses and relays and none are drawing voltage. I then disconnected the alternator by removing the positive lead from the battery and the draw went away.
In order of ease of execution, what do I do next to track down the draw?
Note: Please be aware the alternator on this vehicle is in an almost impossible location to access without removing it completely - a really difficult and time-consuming task. The intake, upper fan shroud, serpentine belt and fan blade (if I want to extract the alternator more readily) must be removed and the alternator itself is wedged into a mount requiring quite a bit of finagling to get out and back in. Almost any task short of this one would be preferable. Thanks!

[MountainManJoe]

Do not multi-post. Keep all your related troubleshooting under one topic please. It makes no sense to go hunting all over the forum for the history. People can see your topic just fine. Merging now.

[Rein]

OK, thanks Joe.

I wanted to make sure about which cable was connected to the draw so I decided to go out and disconnect the heavy red cable going from the positive battery post to the fuse/relay block and that removed the draw! Now that I knew it had to be somehow connected to that fuse block I went back and instead of testing the top of each fuse for a voltage drop with my DVOM I removed each fuse to see if any were creating the draw and it turns out it was the 30A FRT HVAC fuse!!! No idea why my previous testing method didn't work, but at least I've narrowed it down to this circuit.
What does FRT stand for?
I have the Chiltons manual, so can anyone direct me to the wiring diagram and/or relevant pages in that manual so I can locate this fused circuit and continue to figure this out?

[MountainManJoe]

The wrench icon doesn't have any options that you describe.

You don't see this?

I disconnected the positive battery terminal and the draw disappeared

Well that's not really what I said. You need to disconnect the alternator only if you want to eliminate it as the cause. If you disconnect everything (fuse box, starter, everything) then that doesn't really help you. And when you say "disconnect" , you still have your meter in series completing the circuit right?

If the cable was for the alternator only, then there you go. You found your culprit.

I have a Topdon battery load tester. I'll attach the reading

OK so battery is probably good.

the alternator on this vehicle is in an almost impossible location to access

Oh I know. These are the joys of owning a van. The Astro has zero working space under the hood. Servicing anything means removing half the crap under there. But if I recall, I was able to reach the alternator terminal from the inside by removing the doghouse.

[MountainManJoe]

it turns out it was the 30A FRT HVAC fuse!!

Oh there you go. Nice work.

What does FRT stand for?

Front.
Rear HVAC was an option for the Astrofari.

can anyone direct me to the wiring diagram

I gave my Haynes manual away, but it should be in there somewhere.
Two possibilities come to mind to though. The biggest HVAC power hogs are the blower motor, and the AC compressor clutch. So see if unplugging them makes the current drop.

[MountainManJoe]

FYI full schematics and harness routing diagrams, pinouts, etc are available on gmupfitter.com