Jim,

Thanks for the quick reply!

A couple other things to note:

1) If I disconnect the single wire from the sending unit on the manifold, the OPS is still inoperative, both the old one and the brand new one from MB.

2) I learned on diesel discussion forum that once the pressure sending unit on the manifold detects about 1-1.1 bars it creates a ground circuit and switches the OPS. What has me puzzled is that disconnecting the sender should cut that ground and the OPS should work fine…but it doesn’t.

Any thoughts?

Mav

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'91 350SDL 165K miles
Lovin' her until she blows...
'01 Dodge Ram Cummins 4X4 DWR
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