Thanks Geoff, I guess that either means it is not reporting it or it is not working then.

Ok thanks geoff.
Am I likely to have done harm then as it seems to have solved the issue I had?
I only remembered from years ago using it this way to get the hold light on the dash flashing the error codes.

Yes I've just checked, I didn't use a lamp (was going to look for flashes on dash), just a direct cable between those two.
Is that not correct, pretty sure it is how I did it many years ago from PhilMcfadden's instructions.

Could that have just reset the fault?
(fault possibly triggered when ...

I've managed to turn off the air bag warning light, but not sure why this would happen?

I connected the relevant pins in the diagnostic box - D +B Switched battery voltage to T FAB Trouble code output (air-bag diagnostic monitor computer)
Then when I started up expecting some fault codes I got ...

Ok, thanks Geoff. I've got a few things to try. I'll report back if I manage to solve it

Yes Geoff, this was a schoolboy error of mine... missed putting the insulating washer back on when putting the alternator back.
I was wondering if this could have had an effect on the air bag light issue?

Did you manage to sort it?
Mine has today just started doing the same. Goes off briefly after starting but comes straight back on and stays on. Doesn't flash.
I did have it flashing about 6 times a while back but not every time I drove. It did that for a couple of months but then no problems until ...