Only because this clubhouse site is so seductive, hoping for easy answers.
I am in for learning automotive wiring like it or not. I would like it if a club guru could appear in the shop, keep the education as simple and direct,... not going to happen. Neither do I imagine any of you have the time or inclination to type such an education.
Is there a website, archive thread, (No tech FAQ I see) I can reference that applies to our 37 year old cars ? Google searching finds instructions for tracing a battery draw, disconnecting GPS, air bags, rear facing TV,...
Followed by long winded instructions for attachments to the negative battery post, to plug in the multimeter, then another plug in for the new car fuse box.
For what it's worth, there's been the draw. I checked the lights, turn signals, to find a tail light bulb out. Not the bulb.
Welcome to auto electrics, schematics, wire bundles 101. Mommy !
Tracing battery draw.
Being a tech that loves older cars, this is how I would do it.
You're going to want a multimeter that does 10 amps, make sure every thing is turned off, doors/trunk closed.
disconnect the positive battery cable, and "jumper" the battery post + and the positive battery cable, using the multimeter leads. Then you should have a reading.. I would assume this car would have a very minuscule draw, less than .5amps is generally what you aim for, so once you're all hooked up, if you are over .5amps, one at a time start pulling the fuses out, most of the circuits won't change the number much, but One should drop it significantly if you are over the .5amps.
Then you just have to continue following the circuit untill you can find what's causing the draw. (Prsumably using a wiring diagram)
If it's you're first time, buy spare 10 amp ceramic fuses, you're probably going to fry a few, you don't want the dome light, or headlights, to accidentally come on as your meter is hooked up.
So far on my car (I've had it week) I found the hazard switch pops out, and drains the battery over night by flashing my lights.. Lol. I don't have wiring diagrams, or experience knowledge with these cars, but they appear to be quite simple, good luck!
You're going to want a multimeter that does 10 amps, make sure every thing is turned off, doors/trunk closed.
disconnect the positive battery cable, and "jumper" the battery post + and the positive battery cable, using the multimeter leads. Then you should have a reading.. I would assume this car would have a very minuscule draw, less than .5amps is generally what you aim for, so once you're all hooked up, if you are over .5amps, one at a time start pulling the fuses out, most of the circuits won't change the number much, but One should drop it significantly if you are over the .5amps.
Then you just have to continue following the circuit untill you can find what's causing the draw. (Prsumably using a wiring diagram)
If it's you're first time, buy spare 10 amp ceramic fuses, you're probably going to fry a few, you don't want the dome light, or headlights, to accidentally come on as your meter is hooked up.
So far on my car (I've had it week) I found the hazard switch pops out, and drains the battery over night by flashing my lights.. Lol. I don't have wiring diagrams, or experience knowledge with these cars, but they appear to be quite simple, good luck!
81 528ia black - semi-dd
92 BMW K75 - dualsport/cruiser
03 Chevy Silverado 1500hd - tow-rig/bad weather
84 Toyota celica supra - drift/autox/hillclimb duty
92 BMW K75 - dualsport/cruiser
03 Chevy Silverado 1500hd - tow-rig/bad weather
84 Toyota celica supra - drift/autox/hillclimb duty
-
franky2fingaz
- Posts: 136
- Joined: Mon Jun 06, 2011 10:33 am
- Location: PEI
exactly.. as Qwodracer said ... pull the fuses out one by one. The funny thing is, old bimmers you can just put that meter on and work very quickly. The much newer (and less desirable) crap you have to wait 30 minutes or more for things to go to sleep (modules).. like this X5 4.8 in the shop with more than an amp of draw, holy.. !
'80 M535i
'08 528
'15 Tacoma 6-speed
'08 528
'15 Tacoma 6-speed
I had a current draw in the car that the previous owner and several mechanics had not been able to sort out for more than 10 years.
They had identified two fuses that needed to be removed and replaced to keep the battery from draining.
It took me about a year. I noticed an intermittent switch in the voltage polarity + to - switched on a few of the places where fuses plugged in. This was traced eventually to the hazard switch. I am not suggesting the same fix for another e12, but I was surprised at how elegant (read complex) the wiring was compared to my 1970 dodge.
They had identified two fuses that needed to be removed and replaced to keep the battery from draining.
It took me about a year. I noticed an intermittent switch in the voltage polarity + to - switched on a few of the places where fuses plugged in. This was traced eventually to the hazard switch. I am not suggesting the same fix for another e12, but I was surprised at how elegant (read complex) the wiring was compared to my 1970 dodge.
I bought my 76 over 10 years ago for cheap because it had a current draw. The PO had installed a large marine style main switch under the hood that had to be turned off every time the car would be parked for an extended period of time. (Over 4 hours.)
A month into my new ownership, while connecting a new battery (since I had killed the old one) I heard a click. Disconnect, click. Connect, click. I chased it to a relay in the fuse box. It was the relay to the fog lights. I do not have fog lights. I removed the relay and the battery drain is gone. I removed the master switch and have not had battery drain issues since.
A month into my new ownership, while connecting a new battery (since I had killed the old one) I heard a click. Disconnect, click. Connect, click. I chased it to a relay in the fuse box. It was the relay to the fog lights. I do not have fog lights. I removed the relay and the battery drain is gone. I removed the master switch and have not had battery drain issues since.
Pierre in Camarillo
76 530i (3.3), 69 2002 (M20), 74 tii, 75 2002, 79 323i, 84 733i, 84 323i (S52), 91 318is, 96 318ti (S52), 97 Z3, 01 540i, 02 330i, 02 1150RTP.
OO==00==OO
76 530i (3.3), 69 2002 (M20), 74 tii, 75 2002, 79 323i, 84 733i, 84 323i (S52), 91 318is, 96 318ti (S52), 97 Z3, 01 540i, 02 330i, 02 1150RTP.
OO==00==OO
Update for concerned viewers, I could have gone straight to the hazard switch as grey suggested. It was working perfectly, but pulling fuse 5 for that circuit stopped the draw. Nothing else on the circuit is of any large consequence for general transportation purposes, so there's time to fool around fooling around.
I am curious how the trunk lid didn't open high enough to be easily noticed in those years, ... but my own electrical ludite learnings understand anything is possible.
Latest fooling around included improper multimeter probe connection, disregard the update.
On to replacing the battery. Three years old, but subjected to sitting on the bench 4-5 winter months of car storage. Always kept charged to avoid freezing but I suspect that kind of disuse may be the cause of the voltage drop in a day or two of just sitting.
Latest fooling around included improper multimeter probe connection, disregard the update.
On to replacing the battery. Three years old, but subjected to sitting on the bench 4-5 winter months of car storage. Always kept charged to avoid freezing but I suspect that kind of disuse may be the cause of the voltage drop in a day or two of just sitting.