[s-cars] Central locking system problems

[willem.smit]

Hi,

I've just bought an 1992 S4 avant and I'm having trouble to get the central locking system to work. The previous owner told me it just stopped at a certain moment in time.
 I've got power + ground at the central locking pump under the backseat, but the pump doesn't engage/ pump when the doorkey is turned. How should I proceed. BTW I've tried, with no luck, 2 other pumps at a local junkyard.
Who can help me out.

Thanks, Willem (The Netherlands)