airborne

i don't. here's the deal. my fans will not run after shutdown AND something is draining the battery. hooked up a voltmeter between the pos batt cable and terminal and when the car is off i'm getting 12v. then i ungrounded the fan wire. down to 8v. any guesses where my drain is and where to look for bad wiring? got the bumper off (thanks to those who helped) and am looking at the harness and stuff. relays are good

tia

sszablya

Look for anything that is wired to come on w/o the ignition key - lights, map lights, trunk light, aftermarket stereo equipment - make sure you didn't leave anything on.

Then, make sure you have the fans wired right. I take it (since you specifically mentioned this) that your fan switch is modified to come on after shutdown?

paw140

I don't understand how you went from 12v to 8v by *ungrounding* the fan wire? You should be measuring amperage, not voltage, to find a drain. Hook up an amp gauge inline with your battery and then unplug fuses one at a time until you find the drain.

SoCalLove

I'm going w/ sszablya and saying its your system. What kind do you have if you got one? And what kind of battery do you have?

airborne

i was told to try this with a test light, best i had at the time was the v-meter. pulling fuses had no effect on that. so i started playing with fan stuff. just to be straight i'm referring to that random wire in the passenger kickpanel that has the effect of forcing the fans to run after shutdown. try again with amp meter?

i'm almost totally certain it is a fan issue. aways back the fans got jammed on the shroud and it melted connectors and wasted a couple of the relays. got it sorted out but not well enough i guess.

airborne

oh, and i have the stock bose system. though the cd player doesn't work. i think thats standard though

sszablya

Well, there's really only two ways to drain a battery. One is by having a switch that is left closed (on); the other is a dead short. If you have a dead short, the battery terminals would get hot, and the battery may burn.

Here's how to test for a dead short:
Unplug the negative battery cable and test for Voltage. Assuming no voltage, then test across the negative cable to the positive cable, for continuity, using a DMM.

If you get continuity, there's something connecting the (-) and (+) battery cables, and they should be uncontinuous with no battery.

Now, if there's simply a switch left closed (on), you just need to find the switch and unplug it, or switch it off. A switch could come in the form of a traditional rocker, but it could also be a relay. Relay's are essentially high-current switches.

I have no idea what you're talking about with the "random wire in the passenger kickpanel that has the effect of forcing the fans to run after shutdown." Just take that wire and put it back wherever you found it. It is more than likely not a gound wire, as the fan motor would be grounded close to the fan itself.

Hypothetically speaking, if you did want to have your fans switch on after engine shutoff, you would want to pull a positive(+) wire; removed from the (+12v) ignition circut and reinstated in a (+12v) constant circut. Not ground.

Are you absolutely sure that the battery is not bad? The symptoms you describe are very similar to symptoms of a battery that has a cracked plate or low fluid levels.

airborne

the wire i'm referring to is explained here:
http://www.scuderiaciriani.com/rx7/fan_mod.html

which explains the stock system for running the fans post-shutdown.

i have two different batteries i've used and both are pretty new. they are hawker odyssey batteries, relocated to the bin. the timing of the relocation doesn't suggest its causing the problem though.

battery isn't heating up or anything. did test fan relays.

thanks for the help so far, this has been frustrating me for some time!

Kahren

iTrader: (13)

disconnect one of the baterry termionals from teh baterry and see if teh baterry still dies in the same amount of time if it does its not teh car its the baterry. sopmetimes they just internally go bad

sszablya

I guess I'm confused.

Does this problem occur when you're not doing the fan mod? Because, if the fan mod is triggering the battery drain then that's you're answer. If you replace the wire to wherever it came from, does the problem go away?

Why do you need your fans to come on after the car is off? Just open the hood.

airborne

I'm way more confused, its ok.

Happens with and without the fan mod, dunno if the battery dies faster either way. Plus the fan mod is ineffective. Any explanation for my 12v/8v difference?

Have you ever sat in the car after you park it? my previous 3rd gen would heat up enough after it shutdown to actually move the stock temp gauge. after i did the fan mod it was fine. now that i have a power fc i see that even with the hood up, a floor fan on, and the two cooling fans going full blast the car will go from 83c to about 103-105c before the temps start to fall.

sszablya

Here's the problem: You should always have voltage on the battery. It's used to run the alarm, stereo memory and other "always on" things.

So I just contradicted myself... ignore my previous post about continuity.. I meant current.....

Okay.. Your battery should *always* produce a ~12v signal from terminal to lead. As for it dropping to 8v, I would actually try and duplicate the 8v problem... Sometimes one can get false reading from a voltmeter. BTW, make sure the leads are properly plugged into the meter and connected to the test subject.

Really, PAW140 had it right. To find a gremlin like this, you should measure the CURRENT across the + and - cables, and the RESISTANCE should change. If the resistance changes drastically, you probably have a short. if it's just slight, then you may not.


Here's what I think of the 12-8v thing anyway:

We all know that (V=voltage/I=current/R=resistance)

V=IR

so if the resistance decreases (adding another path/wire), the Voltage must also decrease proportionally.

I just can't figure out why it's a 4V difference. Can you measure the resistance from the (+) to (-) cables (unplugged) and see if it changes significantly when you ground that wire?

airborne

Hmm, good point. Didn't think of the few 'always on' things. Will retest the 8v mystery tonite, but i was pretty careful about it. Just touching the now-infamous fan wire to ground did it.

Will also switch to the multimeter and check things out again measuring current. Including resistance across pos/neg cables.

I'll revive this sure-to-be-dead-by-morning thread tomorrow. Thanks for the know how sszablya.

sszablya

airborne, I had a new thought: do your fans come on when the car is on?

edit: BTW, I understand the fan mod now... sounds interesting. I may do that to my rex!

airborne

yes the fans come on when the car gets up around 80c. plus if the car is shut down, but ign is in the 'on' position turning the AC on will get them to run.

whats the new thought?

wasn't gonna reply, worked late didn't get a chance to check things out...

sszablya

I hear ya... I spent last night pulling cars outta icy ditches and such...

Here's what we know so far:

-The fans work.
-The battery dies easily under any circumstances (gounded wire or not).
-Grounding the "fan mod wire" does nothing to the fans.
-The Voltage decreases when the "Fan mod wire" is grounded.

Here's what I do not know so far:
-Is there +12v on the "fan mod wire?"
-Where does the "fan mod wire" come from? Is it connected to the fan controller?
-Verified condition of the battery(s)?

airborne

A little searching to learn about the 'fan wire' revealed this:
"could have grounded the the fan test point behind the ECU (black female spade connector behind the ecu, part of the fan recall, little black box, 2"x 2"x 1" black box, also part of the fan mod)"

in this thread:
https://www.rx7club.com/forum/showth...hlight=fan+mod

good write up here that i shoulda found before posting:
http://www.scuderiaciriani.com/rx7/e...oting.html#DRA

and last but not least this is some really informative stuff from skunks:
"K here is what you do, first get a multimeter with a DC amp setting. Then turn off car and disconnect the positive side of battery terminal, place the multimeter between the battery and the positive cable (do not start car or it will blow our your multimeter). With everything off, it should read about .2-.4volts (this is the ghost amp draw from the stuff like alarm and clock and stuff like that). If it's more then that, you got something that is grounding itself. Next step is to start pulling all the fuses and relays you can find, once you pull one and see that the amp draw drops, that fuse eletrical system has something wrong with it, check that wire and that system. If nothing can drop it like in my friend's car, its probally along the main eletrical system or something that is not fused like an aftermarket alarm or the ecu. Grab someones manual (remember to return it after you use it) and then check the eletrical schematics and hopefully you can track it down. "

from this thread:
https://www.rx7club.com/forum/showth...hlight=fan+mod


can switch to my other battery, unlikely (but possible i suppose) both are bad. and check that wire for V.

building up a nice to do list. thanks for stickin with it!

sszablya

So the only major electrical work you've done is the battery relocation? does the car start/drive okay?

sszablya

Oh, and the quote above is confusing...

It says to pick the DC-A setting on a Multimeter, but measure DC-V. Current and Voltage are two very different things.

BTW, I'd go check my car, but it's snowing relentlessly and my car is under a cover.

sszablya

Okay, I've got some more thoughts for you... If you're measuring Voltage with the car off, from the batt. terminal to the cable, you should only measure about .3 Volts. This is the Voltage across the diodes (because of the nature of diodes) in the solid state circutry that stays on after key removal. You would measure the same Voltage across any unpowered diode.

Because of the resistance of the Multimeter, you probably aren't able to measure the voltage on the key-off circuts, because (if you do the math) there isn't enough voltage after the multimeter to even close the circut in the solid state devices. You need somewhere near .7 volts to power those babies.

In order to measure higher voltage, you need more resistave load on the circut.

SO.... If you're measuring 12V, from the (+) term. to the (+) cable (key off), you've got a resistive load somewhere in the circut. This could be a light, a stereo, a short, etc.

The only way to measure load on the circut is to take off BOTH the (+) and (-) cables, and measure the resistance across the two cables. It should be phenomenally high, in the 10,000 - 100,000+ Ohms range. IF you're getting a lower resistance than, say, 500 Ohms, you've got a good short. If it's 100 Ohms or lower, there's a very serious short.

Also, if you continue to get +12V - +8V when opening/closing the "fan mod wire", you may just want to test the voltage like you were, but UNPLUG the fan controller and see if your problem goes away. The fan controller may be bad.

If you're using an analog meter, throw it out and buy a Digital one, as analog meters typically fail (that's why they're so cheap!).

With that battery relocation mod, please tell me you have a fuse ON THE (+) BATT TERMINAL!!

Also, how do you combat Hydrogen buildup in the passenger compartment, from the batt. charging with the alternator? (See: "Hindenberg")

airborne

Can probably find it with the manual but as i'm at work, anyone want to mention where the fan controller is?

Got digital

Don't hate me, when i say no fuse. But it is hooked up to the same place the stock batt was.
As for the question...my power windows work.
Ignorance is bliss i guess. I know a kill switch on the battery is recommended but haven't heard the fuse yet.

sszablya

I'm just worried about running longer and longer battery cables without a fuse. Fuses simply protect the Wire and electronics from catching fire (I'm a poet!) in the even of a short. There's a reason that the stock main fuse block is attached directly to the battery.

And come to think of it, I'm not sure where you'd find a giant fuse either, but a kill switch would suffice.