battery drainage: update and more q's
 

My car won't hold a charge for longer then 4-5 days. 6 months ago when I got it, I put in a new battery and negative cable. All's fine as long as I crank it up and put a few or more miles on it every other day. I don't know a thing about electrical but with some directions I'm pretty good at figuring things out.

I know a lot has been mentioned about this and I'll do some searching, but in the mean time what have you done to fix the problem? Is there a 'usual suspect'? Thanks

1990 C4 cab with about 120k miles

Trunk light, engine light, glove box, interior lights light on when it should be off, bad relay. Connect a multimeter in series with the negative battery terminal. Start pulling fuses/relay's. If you see the current, and then a drop when you pull a fuse, you may have found the culprit. Not sure what the normal draw is(clock/alarm), but a search should give you the information.

+1 - that's the easiest way to figure out what's wrong. Use a multimeter and start pulling fuses. Let's hope it's not Fuse #1, which supplies a lot of power to the aircon and heating system and can draw a lot of power if your CCU ("Climate Control Unit") has failed.

Check the interior light switches in the door jambs ... that was what the problem on mine turned out to be. I cleaned them up, and replaced the perished rubber covers, which I think were letting moisture in which was shorting the contacts.

Some help - first time I used a multimeter. When I hooked it up and pulled the fuse relating to 'inside lights and clock' the needle fell from about 100 to about 50, so that's the culprit, right? Now, with that interior light between the sunvisors, it never went on when I'd open or close the driver's door. When I'd open the passanger door, it would go on and the needle from the meter would tap out at max. If I'd move the light setting to middle, the light doesn't come on but needle would still tap at max when opening passanger door. The driverside door has no affect on either light or meter, so does it make sense that somewhere in that switch or wiring (driver's door) is the drain? I pulled out the switch as far as the wiring would let me and it looked fine. Do I access that are from the driver's foot well? Am I totally off mark?
Thanks.

Did you check the switches in the door jambs? That would be the first place I'd look.

Only checked how I mentioned above. How else can I check 'em?

Someone has to have my answer?!!?

It appears you're on the right track in determining an issue with the drivers side light circuit including the light itself. My car doesn't have this light but I assume when you say that the light does not illuminate when you set the switch to the middle position that this is the manual override and indicates a problem with the basic operation of the light/switch itself. I would investigate in getting this basic operartion working (i.e. making sure you have 12 volt power at the light switch and checking that the switch actually switches the voltage to the light) and the other functions may fall into place. The door switches work by completing the light circuit to ground so there should be 12 volts at the wire. The switches can be checked by pulling them out and bench testing them with the ohmeter setting on your meter testing that the switch continuity between the wire connection and the threaded body of the switch works by pushing the plunger in and out. As a process of elimination, you may want to pull the clock (i.e. a faily easy task) and see if the other 50mA dissappears . BTW If you're interested in measuring the actual current when the needle pegs to one side of the scale, increasing the current range switch on the meter to get the needle in the middle of the scale is required.

Here's a thread with my battery drain experience:

LINK>>>> Overnight battery drain - door light switch

Thanks for the info - the light does work via the passanger door, just not the drivers door, so I'll check the switch as you described (the rubber cover wass missing from this one).
How do you pull the clock? Very carefully, I suppose.

Without the rubber boot, the switch is exposed to moisture and may have a corroded contact. They're easily reconditioned with some fine sand paper. The clock is held in by the rubber surrounding it. With some soapy water to lubricate the rubber/clock I/F you should be able to twist it out with the help of some popsicle sticks or the like for prying.

Fogcity, where are you located?
I know if you were close to me, I'd help you in person. Maybe another rennlister lives close by that can help? Tracing electrical gremlins can be a PITA!

Checking grounds for things like stereo, lights, etc is also a good use of your time. While you're chasing the gremlin, be sure to address anything and everything you take apart to make sure it won't fail in the future. Preventative maintenance in the best kind!