[Frobius]

Right, firstly I'd like to apologise for the lack of pictures. I've already finished and put it all back together, but thought that my experience might help someone else.

So the past few mornings, my car has been a bit slow to start. It's pretty much because my daily commute is 2 miles in each ditection and so the battery ain't getting a decent charge. I gave it a 20 odd mile run but that only worked for a day. This morning it just wouldn't start. Rather than mess about jumping it, I thought I'd leave the battery on charge today and tonight and take the mrs car to work instead. Because it was raining and I now couldn't get my car into the garage, I removed the battery and put it in the garage to charge.

I got home tonight at it was showing 13v so I put it all back in and it started, albeit slowly. However, the airbag light then came on.

INPA wouldn't clear the error (showing as "battery safety clampe") as it was still present. After a bit of googling, it seems that the car has a safety system that cuts the main supply to the engine and alternator in the event of a crash as part of the SRS system. It's not however the explosive system that the Americans have, instead it uses a gas charge to push the cable out of a socket. Anyway, at first I thought that I must have tripped that system somehow when I disconnected the lead for it from the main B+ terminal block. It's a little black wire that terminates in a black plastic connector that plugs into the back of the positive terminal block (the main one, not the distro panel atop the battery).

After a bit of diagnosis, when plugged in, INPA was saying that there was too little resistance and when disconnected, too much. I checked the plug and there was no short so I then thought I really must have tripped the safety clamp.

But then I looked at the socket that the plug goes into - inside, there is a little metal flap that springs up onto the two pins and shorts them when there is no plug in the socket. Looking at the plug and socket, it looked as though something had either broken off when I pulled the plug out initially, or had fallen off and was now long gone. Whatever it was was meant to push the flap down and take off the short. It didn't seem to have any resistance itself not be connected to anything else, so I though bugger it, and pulled it out, leaving the pins now not shorted.

Tada! When all plugged back together, I was able to reset the airbag fault code and all is well again. Now I don't know what the little short was for but I can only assume that it designed to stop any surges when plugging in the plug or what it that might set off the safety clamp - a replacement one is apparently a few hundred quid! Now I've no intention of taking it off again - I'll bought a little CTEK chargerso I'll just charge in the car from now on.

So.. Does anyone more in the know than I know what the spring loaded short is for?