MBWorld.org Forums - EGR valve doesn't open

Hi everybody,
I have 1995, E320 (180,000 miles) and it just failed smoke test because of higher Hydrocarbons (68), and the limit is 53 HC. The car is running like a charm, exactly like 15years ago when we bought it.
I did a Tune-up about a month ago, new spark plugs, cables and replaced one coil that was bad in that time. The oxygen sensor is about a year old and the Hydrocarbons are running “68” which doesn’t seem that high anyway, because in 2006 the maximum limit of the HC used to be” 81”, and the car passed with no problem. But since then the state of California lowered the Hydrocarbons limit, and my car doesn’t pass the smog test anymore.
The only thing I did find is that, the vacuum valve that operates EGR valve is not getting ground and therefore EGR valve does not open. Otherwise the EGR valve works with vacuum pump.
What actually triggers the vacuum valve to open?
Does anybody have wiring diagram of the EGR system?
When does the EGR valve supposed to open?
Any ideas?
Thanks in advance. Jan