PeachParts Mercedes-Benz Forum - View Single Post - Tach fixed - but now some sort of electronic whine at 2000 rpm

Jeremy5848 · #3 02-19-2009, 01:23 AM

The '85 300D (W123, OM617) has the EGR computer behind the right front passenger's kick panel, close to the OVP relay. There should be a "door" in the kick panel. It's easy to pop out the door and see if the noise is coming from there, harder to remove the entire kick panel. With the OVP relay gone bad, the EGR computer was not working. Since your whine started at the time you fixed the OVP, it is a good possibility that the noise is coming from the EGR computer. The tach signal goes through the EGR computer; you might be hearing a harmonic of it. Depending on how loud it is, you might choose to ignore it.