I have a 1994 c280 with a PO441 code. I ran the car at operating temp and noticed the purge valve was not cycling on/off. I went ahead and borrowed my friends scanner which has activations and tried to manually activate the purge valve, but still no clicking. Unplugged the 2 prong plug at the purge valve to check for voltage and ground. I am always getting 12v on one side, but not ground on the other. My understanding is that the control unit cycles the ground on/off to the ground side of the purge valve. While activating with scanner, I never get switched ground from the ecu. Do I have a bad computer? I'm going to check for a ground signal right at the ecu to make sure tomorrow.

Also, I tried manually giving ground to the purge valve and nothing happens, no click either. I will try taking the valve itself out of the car and jumping it with a battery, but i'm starting to think that both the valve and the ecu is bad. Anything else I can check to verify before I buy both? I notice the car still has the original engine harness, anyone experience a bad harness causing this problem?