Trying to trace a power drain, NEED OHM reading

[MattM]

I have been fighting with a slow power drain on my car for the longest time, if i dont use it for more then a week the battery is completely flat...

With all fuses in. No lights on, trunk light disconnected, i am getting 0.9 K Ohms

I was just wondering if someone could check their car and tell me what the reading is... preferably 24v swapped to eliminate any differences

THANKS

[bimmerteck]

Ohms won't tell you anything, you need amps ;) 60 milliamps or less is generally considered acceptable with the car powered down and doors closed.

[StereoInstaller1]

I will tell you this right now...you can learn more testing draws using a testlight than any other device... seriously, try it.

[bimmerteck]

I will tell you this right now...you can learn more testing draws using a testlight than any other device... seriously, try it.

testlight in this cast has to have an incandescent bulb BTW non of that new LED mumbo jumbo either. ;)

I still prefer my labscope, but I'm geeky like that. :)

[MattM]

so i switched the multimeter over to mA, and it showed 42.2

BUT i turned on my low beams, and it dropped down to 41


Where do i connect a test light?

i pulled all the fuses out and it still reads 42?!?

[whodwho]

Sounds like you are going to blow the fuse in your meter, you cannot subject it to that kind of load.

If you have an alarm or radio amp you don't want to just connect the meter to the cable and battery post. if you touch the batt cable to the post and it sparks much then the surge will blow the fuse.

You want to have the batt cable terminal touching the battery post and the test leads on the post and cable and then separate the cable and post to keep from subjecting the meter to the initial surge of the connection and don't turn anything on while hooked up this way. Also turn the interior lights off and disable the trunk light.

You can hook a test light between the unconnected cable and battery to see the draw with the test light and then start pulling fuses.

[StereoInstaller1]

You can hook a test light between the unconnected cable and battery to see the draw with the test light and then start pulling fuses.

Exactly. Pull the ground terminal (or whichever is easier) and attach the testlight to the battery terminal, then put the probe end on the battery cable. If there is a draw, it will light up. Keep pulling shit until it goes away, then chase with the ETM.

Make sure you do something about ALL lights too, they need to be off.

Remember to see if the alternator is bad, or wired wrong. Start by taking C101 apart.

GL!
Luke

[MattM]

ok, i took the 5w bulb from the trunk light, and put some aligator clips on it, when i put it between the ground post on the battery and the ground cable the filament glows orange a bit, and then goes out...

i think i have a spare 1.2w interior light i might try.. the 5w is probably too much?

Alternator is good, when the car is running the voltage is 13.94 at the battery.

[MattM]

the 1.2w lights up dimly, if i unplug the cluster and antenna it is basically out.

hmmmm

[StereoInstaller1]

Basically, it sounds like you don't have a drain.

Change batteries and re-test.

BTW: sometimes when an alternator fails, it puts out voltage just fine, but won't "shut off" and the fields are still working when the car is off. That can happen when a rectifier fails. If it is warm when the car is cold, that is the issue. Very common issue on fords, but can happen to any of them.

[MattM]

Ill have to check out the alternator in the morning. I didn't know they did that.

[MattM]

seems i have fixed it, 2 days later on a not fully charged battery and it started with ease! :D

[Kershaw]

self healing e30 or did you actually fix something?

[MattM]

i disabled the battery charge on the SI board, unhooked my power inverter, and unplugged the antenna for now, i think it was the SI board more then the antenna, so im going to plug the antenna back in and see.

Im going hook the inverter up to a different battery and see what its drain is even when switched off...

[bzboardz]

I had the same problem..it was my antenna. I left it unplugged as I never listen to the radio anyway. Glad you got everything worked out