I have a 83 500sl thats idling at about 1500-1600rpm. I'm using the testing from the Service manual CD.

Disconnecting or reconnecting the connector onto the idle control valve causes no change in idle speed.

With a multimeter I'm reading approx. 13 volts from the connector that plugs into the idle control valve. If I push the connector part of the way on the idle control valve and try to get a reading by connecting the multimeter to the still exposed portion of the idle control valve I get nothing. If this is the correct way to test this the manual says I should be reading 5v +/- 1.

Am I understanding the testing procedure in where I am trying to read the 5v?

If I apply battery voltage to the idle control valve the idle drops to approx. 500rpm.

If this is correct, then it appears I have a defective idle control unit.

I have previously removed this unit from the car to look for broken solder joints, didn' find any but, resoldered around the connectors as I read this was a common weakness.

Are there any parts forward of the idle control unit that could cause the idle control unit to appear defective?

Any thoughts or suggestions would be appreciated.

Marc

__________________
1983' SL500 euro