potdog

Hi whats the difference between the three connection type oi pressure sender and the two connection type. And why does the gauge read off the scale when not connected to the sender cheers Peter.

FredR

Pete,

This is one of the mysteries of the universe as with why one cannot purchase replacement caps for these items. i have been trying to understand this phenomena for a while and gave up in the end- they do this- it is a fact of life.

kind of interesting that the informed seem to recommend reverting to the earlier 2 pin sender- that's progress for you!

Rgds

fred

ammonman

The 3 wire oil pressure sender on the 89+ cars incorporates a pressure sender and a pressure switch into a single unit. My SWAG is the pressure sender is driving the oil pressure gauge and the switch triggers either the warning light on the gauge or serves as the input to the central warning system incorporated into the digidash.

Mike

L_perm

So, will I lose the warning light functionality when I replace my '91 S4 3-wire with the available 2-wire version?

Louis

ammonman

Unknown as the "Diagnosis of the Instrument Cluster" tech booklet (WKD 495 821) simply shows that the "oil pressure sensor" check range is from 10 ohms to 184 omhs (zero to 5 bar) while the "oil pressure switch" check will set an "OK" message when above 2.5 bar and a "Not OK" message when below 0.25 bar. The booklet gives no indication of the function of the oil pressure switch. It may be the it is a redundant input for a critical "life of engine" reading.

Mike

L_perm

Okay. Thanks.