[urq] Wiring Issue / Battery Drain

[urq]

... to find a battery drain you need to focus on current, not voltage.  What
I do is to shut off the car and set the meter to the 2Amp range.  You need
to be careful because if things are on they can easily blow the fuse while
measuring ... be SURE that the coolant fan isn't going to be coming on while
testing.  Also make sure all dome lights are turned off.  

The next step is a bit tricky.  What I do is to loosen the battery
connection (I typically use the ground terminal as it is not as likely to
cause sparks should a wrench touch something grounded), and then I attach
the (-) of the meter to the battery post and the (+) terminal to the body of
the car.  Now you can disconnect the battery connection and the ammeter will
close the circuit.  Of course if you don't have radio codes or anything
similar to worry about you can just disconnect the ground cable and install
the meter ;-).

Now you should be reading somewhere around 50mA or less of current flow from
the battery.  If you're seeing hundreds of mA you are seeing your problem.
Now the thing to do is to start opening circuits by pulling fuses until you
see the current drop back down to something less than 100mA.  Remember to
reinstall each fuse after removing it for the test.  

Sometimes current drains can be insidious ... they can come and go.  If you
find the current draw to be small you may need to leave the meter hooked up
and come back and check it every once in a while to see if the drain picks
up.

... all that said, another troubleshooting tenet is to check the last thing
that's been changed ... if the headlight mod is a recent update, I'd
recommend focusing on that area.  Perhaps there are relay coils which are
energized when the car is off, or some sort of miswire which is leading to
an excess current drain.  

Now that I'm thinking about a 4kQ ... the first thing I'd check is the
wiring loom going to the trunk lid ... unless of course you've already dealt
with that one.  When I got my '85 the loom was so bad that the tail of the
car was a light show at night!  :-)

Other miscellaneous comments:
 - based on your voltage reports I would not say that your alternator is
suspect.  
 - Your "unexpected" voltage measurements at the fuses are probably due to
the fact that the circuit they are protecting is not powered up when you
took the measurement ... I'd bet the ignition switch was off when you did
the test, or perhaps the headlights were not turned on ... 

Good luck!
Steve B
San José, CA (USA)

-----Original Message-----


Ok, This is driving me nuts.
Patient is not my ur-q but rather my 4ktq.  But its sitting on my ur-q
suspension and has a 10vt engine so its sort of a 4-door ur-q. :-)

Recently my battery started dying.  Battery is fine, but the car will drain
it over a period of a night.  I have recently upgraded my relay/fuse setup
for lighting to a better marine grade unit.  OH, and 4ktq has the newer
style under hood fuse box.  Not the glass fuse style of the 83 ur-q.

So first the background and known issues.
-Upgraded relay setup
-Battery is good.
-Alternator is suspect.  I get 13.5 volts when running. But with lights on
at night "Even just 2x80w low beams, it drops about 1v to 12.5V.

So, here is where it gets weird.
I start looking for a voltage drop.  I go from my junction box against
firewall where my 1/0 gauge cable comes up from battery and then start
probing the fuses.  0.5mv, 1mv, .8mv, etc.   Basically, normal.  Then I get
to fuse 6.  11.3v.
6 = 11.3v
7 = 11.3v
8 = 1.1mv
9 = 11.3v
Etc Etc.

Basically, aver 1/2 of the fuses will show 11.3v.  What the heck.  At first
I thought it might just be in the headlight circuit but now appears to be
all over the board.
  Whats this mean.
-Fuse box is shot?
-Harness has a burned area somewhere that has accessed over 1/2 the wires
going to my fusebox?
- I'm screwed?

Car runs fine when on.  All circuits seem to work.  And when I park it, if I
unplug the negative terminal all seems to be fine.
Please offer suggestions if you have any.

Thanks

Todd



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