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Old 12-06-2010, 10:07 PM   #41
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It's the chupapila.
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Old 12-06-2010, 10:40 PM   #42
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Originally Posted by Joe Perez View Post
This is not unexpected. I'd imagine that the radio has some filtering capacitors on the power input (even the keepalive input) and those caps will suck down a bit of juice when they're first energized. And 5ma seems very reasonable to me- that's 5/1,000 of an amp. A typical Miata battery with a rated 30Ah capacity could supply that load for a little over for six and a half years before dropping below rated voltage.


A couple of thoughts:

1: I like the idea that maybe the keyswitch is continuing to supply ACC (or IG1 or IG2) after key-off. It's easy to test, too: get down there and probe the R/B, B/R and G/R lines for +12v (relative to GND) after you've switched the key off. Repeat several times.


2: I just remembered the part where the wiring has been hacked. Could it be that some relay is getting switched on and is then subsequently being held latched (by its own contacts) which are being supplied by a non-switched source, only to release (and thus thwart troubleshooting efforts) as soon as you remove its power supply by pulling a fuse, disconnecting the battery, etc?
I hate electrical. I'll test the ignition switch tomorrow. As for a relay, I have no idea.

When I put the multimeter in between the battery and the + cable I was seeing the same 5ma. When I would pull the room fuse the multimeter read 0.
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Old 12-06-2010, 11:04 PM   #43
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Originally Posted by levnubhin View Post
I hate electrical.
Heh. Oddly enough, I love electrical when it's hands-on. Trying to talk someone through electrical troubleshooting (either by phone or via the tubes) can be painful.


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When I put the multimeter in between the battery and the + cable I was seeing the same 5ma. When I would pull the room fuse the multimeter read 0.
Now that alone is odd, and makes me wonder a little more closely about my #2 above.

Quick test:

Put the meter between the battery and the + cable. You should probably start with the meter in the higher current position to avoid smoking it.

Next, turn on the key. Don't start the engine (that'll definitely pop the meter), just key all the way up to run. Eyeball the meter to make sure you've got a solid reading, and take note of what it is(*).

Last, turn the key all the way off and check the meter again. Does it drop back down to 5ma? If it does then that (mostly) blows my latchup theory, and strongly suggests that whatever is happening isn't dark-current, but merely a shitty battery. Or that it's intermittent and we haven't found the trigger for it.


If the reading noted in (*) above is less than the max allowable current in your meter's lower current position, you can try the test again with the meter in that position to get a higher resolution.


For my reference, what meter did you get? I can probably make these instructions easier to follow if I can see a picture of the meter you're using.
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Old 12-06-2010, 11:14 PM   #44
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Old 12-06-2010, 11:47 PM   #45
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At this point I'd have a reputable place load-test the batt and alt.
If those are good, then go with Joe P's diag routine.
Intermittants are fun!

Last edited by RattleTrap; 12-06-2010 at 11:48 PM. Reason: Cause I'm a mo-ron.
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Old 12-06-2010, 11:51 PM   #46
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Interesting.

Ok, so the milliamps readings (up to 400ma) are taken on the regular + terminal, and only the larger-scale (up to 10A) has a dedicated terminal. That's kind of unusual (most meters I've used had two dedicated current terminals) but ok. So start with the probe in the 10A terminal, then if less than 0.4, you can move down to the +V.Ω.mA terminal.

All readings will be taken with the switch in the mA/A position and the "Select" button set to DC.

And wow, the 10A terminal is unfused. That's a damn good way to blow up a meter. Understand that when you've got the red probe plugged into the 10A terminal that your meter appears to be a short circuit to anything you put it on. So if you were ever to place the terminals across the battery in that configuration, it will almost certainly melt / explode. Not a nuclear armageddon type of explosion, but it'll definitely burn your fingers and make a loud noise. IOW, be careful.
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Old 12-07-2010, 09:46 AM   #47
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I've burnt one of my probes out that way

acutally my DMM is exactly the same. 10A unfused, 400mA fused.
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Old 12-07-2010, 09:57 AM   #48
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I've burnt one of my probes out that way

acutally my cheap $0.5 DMM is exactly the same. 10A unfused, 400mA fused.
You're a jew, so no wonder.
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Old 12-07-2010, 10:17 AM   #49
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whatever, its quality Crapsman!
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Old 12-07-2010, 10:19 AM   #50
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You would probably rollover and die if I told you how much my Agilent DMM costs.
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Old 12-07-2010, 10:27 AM   #51
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I just want something that can do Hz. And I wouldn't spend more than $30 on it
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Old 12-07-2010, 10:32 AM   #52
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This DMM does 20Hz, but tha's the sampling rate, duh.
You need a cheap scope.
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Old 12-07-2010, 10:40 AM   #53
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yeah that too. once i move to a bigger place with a directed work area I will. But I was thinking more to valve operations, like idle and boost to make sure they are outputting properly, its a nice extra test to have.
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Old 12-07-2010, 10:55 AM   #54
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Interested in a used scope from a reputable seller?
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Old 12-07-2010, 02:06 PM   #55
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Quote:
Originally Posted by Joe Perez View Post
Quick test:

Put the meter between the battery and the + cable. You should probably start with the meter in the higher current position to avoid smoking it.

Next, turn on the key. Don't start the engine (that'll definitely pop the meter), just key all the way up to run. Eyeball the meter to make sure you've got a solid reading, and take note of what it is(*).

Last, turn the key all the way off and check the meter again. Does it drop back down to 5ma? If it does then that (mostly) blows my latchup theory, and strongly suggests that whatever is happening isn't dark-current, but merely a shitty battery. Or that it's intermittent and we haven't found the trigger for it.


If the reading noted in (*) above is less than the max allowable current in your meter's lower current position, you can try the test again with the meter in that position to get a higher resolution.


So I did this and with key off I get the same 5ma, switch key to on position and the multimeter keeps going to OF (over flow). I think It blew the fuse cause it wont read now.
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Old 12-07-2010, 02:12 PM   #56
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with key on, you needed to be in 10A mode to start...
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Old 12-07-2010, 02:29 PM   #57
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with key on, you needed to be in 10A mode to start...
Not getting any reading, and my battery is dead now. Going to just get it replaced after work because even if I have another issue the battery should still be able to last more than a few hours before going dead.
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Old 12-07-2010, 02:46 PM   #58
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acutally my DMM is exactly the same. 10A unfused, 400mA fused.
You pussies need to man up and get real meters.

This is the current model of the one I have: http://www.myflukestore.com/p1355/fl...FYvt7Qod0HCxlg (Mine's an original model 77, about 15 years old, which has the same featureset except for frequency measurement, which is pretty damned useless anyway.)

Note that the 10A terminal is fused. This saved my butt once when I inadvertently tried to take a voltage reading across a large 48v power supply with the probe still plugged into the 10A hole.

Quote:
Originally Posted by Reverant View Post
You would probably rollover and die if I told you how much my Agilent DMM costs.
Except this guy. He's ok. (The cheapest meter Agilent makes is better than the best meter Crapsman / RadioShack will ever hope to offer.)


Quote:
Originally Posted by Braineack View Post
yeah that too. once i move to a bigger place with a directed work area I will. But I was thinking more to valve operations, like idle and boost to make sure they are outputting properly, its a nice extra test to have.
A bigger place? You live in a house with three cats and a moose. I live in a 700sqft apartment and I have two scopes.

There's just no substitute for a good scope. Hell, not even a good scope. These days I grab my el-cheepo eBay-sourced USB scope 90% of the time I need to measure something. I recently bought a cheap inductive clamp for it too, which is doubly awesome for looking at things like injector / IAC / ignition / etc circuits as you can measure them without having to splice any wires.


Quote:
Originally Posted by levnubhin View Post
So I did this and with key off I get the same 5ma, switch key to on position and the multimeter keeps going to OF (over flow). I think It blew the fuse cause it wont read now.
Were you in the 10A hole when this happened?
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Old 12-07-2010, 02:47 PM   #59
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Were you in the 10A hole when this happened?
No
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Old 12-07-2010, 02:48 PM   #60
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No
[yoda] That is why you fail. [/yoda]
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