Can anyone tell me waht this is?

[nesty]

I got a 3 pin socket behind my Alternator. I have followed the cable and it appears to go into the gearbox bell housing? Can anyone tell me what this is?

[dj biz r]

i dont know but in the haynes it referred to a diagnostic plug ,which i i dont seem to have ,could it be thus?

[toomanytoys]

It is a "diagnostic" plug, for the VW tool.. dont worry about it, you dont need it..

[nesty]

OK cheers. I did wonder if it was that! However couldn't work out why it was going into the bellhousing?

[syncrosimon]

Its a top dead center sensor, used by the VW ignition timing computer. Its a reed switch.

[nesty]

ok thanks