MB DOC: I really appreciate your response
I checked all the pins they are not numbered at the connector or the computer. No voltage at any with car running. Relay fuse is not blown.
Since I am not sure of the pin numbering I cant check the pickup either.
Do you know which way the pins are numbered?
Since no voltage at ANY I am assuming the relay is at least bad, would you agree?
UPDATE:
I just had someone test the relay and it is no good. Took it apart found the coil not closing the switch. I manually closed the switch with a piece of non conducting plastic to see what happened if it was working. The EGR now gets a signal and works, there is voltage at what I think is pin 1 on the computer, but still no tach.
I can't really test the other pins because they are not numbered.
This is getting really frustrating. I am goining to get a new relay tommorow. Could the Klima relay being defective cause the tach not to work??