rebp911

I’ve been trying to find the source of a battery drain in my 1992 C4. My new Bosch Silver battery would run down after a weeks non-use. I’ve fitted a battery brain to preserve enough to start the engine, while I try to find out what the problem is.

It’s not the CCU fan as I suspected - that turns off properly after about 15 minutes. I found a small drain of about 50Ma on fuse 12 (diagnostic), but wasn’t convinced it was this. So I got in a mobile auto electrician who detected that an un-numbered fuse was generating a drain of about 100Ma.

This fuse is not numbered, so we thought it must be an after-market fitment. The culprit is a 3 amp fuse, which sits next to a 25 amp one in one of the blank cut-outs in the fuse box.

I then tried to trace these wires (4 in total) from the fuse box. I got as far as a point under the dash, when it disappeared into the main loom. So it would not seem to be an after-market fitment. Why would this go back to an un-numbered fuse/

Here are some pics of the wiring from the fuse box.

Could it be the immobiliser? Any other ideas?

Bearclaw

Mine was the boot light. Unbeknown to me, it was apparently unplugged when I got the car. I never noticed or really cared about not having it. My shop plugged it back in when they were going over the car. All of a sudden, I have this annoying battery drain. I unplugged that connection, all good again. I suppose it's either out of a adjustment, or a short or a bad switch. Have never fixed it, don't need it.

rebp911

Barry - I wish it were so simple! Looked at all the hood/engine cover switches, and they're all fine - light goes out when closed.
I think it might be the central locking (PA2000 Hamilton and Palmer). I left it unlocked last night (in a locked garage, immobiliser automatically comes on after 30 seconds) and it was fine this morning. Locked it again tonight - will see what happens.