Tracing battery drain...

[Royalratch]

I assume you can use a meter at the fuse box to narrow down which circuit is drawing current. How do I... do that exactly?

My car used to start after months of standing. Now the battery won't last 24 hours. I must have disturbed something during my ongoing 'resto'

[ranxerox]

please delete

[Grrrmachine]

Ramming multimeter probes into the fuse box will potentially damage the clips that hold the fuses.

If you want to find the drain, follow these instructions

http://www.e30zone.net/e30zonewiki/inde ... tery_Drain

[Royalratch]

Cheers lads - will check it aart.

[ranxerox]

Grrr.
I use test leads with hook clips mostly and they are definitely smaller then the blade on a fuse. Their operation is similar to a spring loaded syringe and "ramming" wouldn't be very good for the test probe.
I'm really not sure if "ramming" test probes into things has been common in your experience. I suspect not.
It's good of you to remind others though. Maybe you could add a wiki bit about it.

I just gave Royal the benefit of the doubt.


over and out
Ranx

[Brianmoooore]

Grrr.
I use test leads with hook clips mostly and they are definitely smaller then the blade on a fuse. Their operation is similar to a spring loaded syringe and "ramming" wouldn't be very good for the test probe.
I'm really not sure if "ramming" test probes into things has been common in your experience. I suspect not.
It's good of you to remind others though. Maybe you could add a wiki bit about it.


I just gave Royal the benefit of the doubt.


over and out
Ranx

Still better to connect the leads in the battery negative lead. Any current flowing in any fuse will also be flowing through the battery lead, so there's no advantage in testing at the fusebox.
The best way to conduct the testing is to fit one lead with a croc. clip, and attach this to the main earth point on the strut tower. Loosen the battery negative clamp, push the sharp end of the probe of the other lead down into the centre of the battery pole, then lift the clamp up off of the pole, take the reading, then return the clamp to its place on the battery.
This avoids any surges when disconnecting or connecting the battery, and preserves the settings of anything on the car that has a volatile memory.
If there is still an abnormal drain when all relevant fuses have been checked (21 to 28 inclusive), then remove the smaller leads from the positive battery terminal, and test for drain with them off.

[DemonDaz]

Brian - That is brilliant, having spent the weekend connecting and disconnecting a meter to try to work out the drain and having to faff about as when I connect the meter the electric arial kicks in giving a surge so can't set the meter to 200mA without doing some playing with wires - hadn't occured to me to connect it and then remove the strap from the terminal!

[Royalratch]

The meter should be set to DC and Amps?

[Royalratch]

So I did this.

There was a draw on the battery of 125 mA which is double the norm?

Removing Fuse 21 dropped this to 118mA but removing fuse 27 dropped it to 79 mA.

Fixing both of these drains will put it back in factory range.

So a result - except those 2 fuses cover a shitload of circuits so it hasn't narrowed it down an awful lot.

[Brianmoooore]

So, removing 21 only dropped the current 7mA. Nothing to worry about there.
Removing 27 drops the current 46mA or 39mA, depending on whether you mean instead of or as well as 21. The only thing drawing quiescent current on 27 should be a few mA by the locking ECU. The rest is probably an alarm hung on that fuse.
Where's the other 79mA going?

[Royalratch]

There's no alarm. I stripped out the remnants of an old Clifford immobilser but I got all of it out.

The only thing I'm thinking is that after I fitted a new roof lining, I left the passenger side light terminals loose - could they be shorting to the body?

The central locking works fine but the interior lights do not come on whatever I do.

[Brianmoooore]

but the interior lights do not come on whatever I do.

Lights off delay module? (On same plate as locking ECU.)
If your loose wires touch, they will blow the fuse, not cause a drain.
Find out where the 79mA's going.

[Royalratch]

How lol.