how to test or check smog pump (air injection pump)? on 1992 Mercedes-Benz 400SE

failed emission test,clucth does not appear to be working

Asked by for the 1992 Mercedes-Benz 400SE
Pump should have power when 1st started cold. If not check for faulty relay or damaged wires. Mercedes has had issues with the insulation falling off the wiring. Good luck!