First, I did search but didn't come back with anything useful.

I'm finishing up some electrical work on my '94 and, after a bad experience last time which I'm pretty sure was NOT my fault (blew an aftermarket guage), I'm a bit paranoid now. I redid the work that caused the problem, and my paranoia has gotten the better of me...

I really want to make sure I didn't make any gross errors in my wiring. So before attaching the battery correctly, I thought I'd just try to get a current reading with the car off and an ammeter connected to a terminal of the battery. If I had a short, I SHOULD see the amps fly up. I don't. Actually, I would expect to have zero or very near zero current draw. It's low, but I'm not sure if it's low enough. I see a steady draw of about 0.25 A with the car off, all lights off, etc... It's just a bit more than I'd expect from the computer and some miscellaneous electrical components getting the power. (Honestly, I didn't search the schematics to see everything that gets power, but whatever.)

Can anyone chime in with their numbers? (With your car off, disconnect your battery and connect a ammeter to the battery terminal and the battery cable you removed.) I want to be sure that I'm not way off here, but as long as I'm the ball park I'll be happy. (Given it's age, my DVM is probably a slightly innacurate anyway.) BTW, I'm using a powerFC. I wonder what the difference in the current draw is with that as compared to stock...

I should probably just connect it, but if I smell melting plastic and silicon again I'm going to be too pissed for words. I've done all the wiring checks I can think of and I'm 99.99% sure everything is wired correctly. *sigh*

Dave

 

Stupid me. I had the door open and the light by the key goes on regardless of the position of the interrior light switch. With the doors closed, it's now steady at 0.03A, which is around what I would expect.

Sorry for the noise...

Dave

 

I think what your asking was recently mentioned in this thread (Post #28 by "wstrohm").
https://www.rx7club.com/showthread.p...light=hose+job

 

Precisely. It should be .025Ohm maximum dark current. I get zero with my water temp gauge unplugged with all doors shut and lights off.

I'm curious though what the ignition on (position II) current draw should be with the AC off, doors shut, dimmers down to min, radio off. I'm getting 3-4A right now and I'm working my way through the fuses and stuff to try and find the source. I wish I had a clamp ammeter since I keep blowing 10A fuses in my multimeter.

It would be a massive help if you can provide that number if/when you're car's working.

Dave

 

You mean 0.025A right? Since my DVM only goes to the hundredths place (not thousands) and my turbo timer was freaking out because a AF input wasn't connected (& flashing all sorts of strange things), I'd say I'm good. As good as I'm going to get for now anyway.

And yes, the turbo timer was freaking out with the car off. I should just ground that input as I don't even use the AFR display anymore...

Well, it's working now. I disconnected the troublesome equipment and successively checked stages until the only thing left was the gauge. I almost messed everything up at one point when I was trying to measure volts but still had the probes in the amp holes on the DVM. Essentially I shorted it out by myself, but everything was OK. (Thank GOD!) (Yes, I'm sure) ;-)

Those numbers are with the engine off, I'm assuming? I'm trying to think of the best way to get that since I'm by myself right now. Did you just turn the key to position II and then attach the battery? That seems like it would just be inviting a big surge into the electronics. If you can wait until this evening, I can ask my wife to turn the key.

Don't we all...

 

Yeah, 0.025A I meant.

I've been putting the key into Ignition II with the neg cable off, then using the ammeter to connect it. Because it was drawing down the battery so fast, (3-4A seems crazy high when the car isn't running), I did it in that order to keep my tests down to 5-10s maximum and not drain the battery too hard. Maybe that's really not much compared to cranking - which is quite possible.

I read here in an old thread that's not a bad thing as long as you don't jitter the terminal connection - On or Off with clean contact, let it rest a half a minute between tests. That supposedly won't harm the electronics. (not that a stock stereo and ECU are worth much anyway).

But if you're going to try the test I think it makes sense to use the key to power the system. I'll try it that way next time and keep an eye on the battery voltage. Another thing I noticed that you can probably test safely is the voltage between the disconnected negative and negative cable with the ignition on. I got 12.65v, where the battery was 12.67. Yeah, that should draw it down quick.

Dave

 

After thinking about it more, I'm not doing this again. If you put the key from off to ignition II, it first passes through ignition I. This gives the circuits on Ignition I a moment to energize, possibly enabling protection for the balance of circuits that are energized on Ignition II. (Just a completely unconfirmed idea with no analytical evidence.) It also reduces the momentary current draw since they both aren't being energized at once. Another point is the wiring diagram GI section says to never do it. Given the cost and difficulty of finding and fixing electrical problems, I won't do it again.

Dave

 

current draw is done with the key off all lights etc off. like you parked it for the night. why do you care what the current is when it is in the acc/on position? cranking think ~100 amps i dont see what you are trying to get?

 

Because I suspect I have a short in my system. With the key at Ignition II, I was seeing 3-4A with no accessories running. It's a separate issue from the dark current measurement.

Dave

 

Sorry about the delay. I got my wife to help me turn the key while I held the ammeter and mine is about 3-4A in position II as well. BTW, it peaked in the 12-15A range when turning the key, but it stabilized at 3-4A.

Considering the alt is charging when you're in this position most of the time, I wouldn't be really concerned about drain in this postion.

Dave

 

Thanks a bunch for the reference point.

Dave

 

No prob!