I have an 83 380 sel that I'm slowly bringing back to life. I'm currently working on the central locking system, and wanted to be sure I had a working pump before doing anything else. In short applying voltage to the connector on the pump produced lots of sparks but no action. I disassembled the pump and found a well cooked motor. (see photo)




I had purchased another pump on Ebay but it turned out to be the wrong one. Anyway I disassembled it and found the motor was identical and looked like new so I removed it and installed it in my original pump. However, when I bench tested it, it would produce pressure but not vacuum. (see photo)



Is there most likely something wrong with the circuit board, or is my testing faulty? If it's that the circuit board is at fault is there anyway to make the pump I bought on Ebay work on my system? (see photo)



Any guidance would be greatly appreciated. Thanks.

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire