As part of the work this week on Superblue, I decided to finally have the two new oil pressure senders (for idiot light and pressure gauge) that I bought some time back installed on her. The problem was the usual one with the OEM style (and probably REALLY OEM) gauge pressure sender – showing all kinds of wild (and inaccurate) pressure readings on the gauge. Also, the idiot light sensor went wacky on me about the time I r/red the oil filter a year or so ago, and the warning light is always on since then. I’m thinking I probably bumped it in the process and knocked that rubber insulation sheath off of it, or some such, causing it to ground out to the block (?).

First up for replacement is the pressure gauge sender/transducer, being the “upgraded” version this time. The tech had a tussel getting the old one out (probably the original), but finally did and installed the new one. However, when we went to fire the car up, instead of reading mid-range on the gauge, it reads all the way to the left (i.e. no pressure). I’m thinking the possibilties for this are: (1) somehow the new sender is grounding out to the side of the block (or, if so, would that make the gauge read all the way to the right instead? ) (2) I bought a blinky sender (although it was still in the Jag packaging, being NOS) or (3) possibly the false “on” status of the idiot light sender is somehow causing a signal to be sent to the pressure gauge sender (or to some electrical interface common to both senders) to indicate that there is 0 pressure.

Of course, if the problem is #3, then when the idiot light sensor is r/red later tonight the gauge pressure sender should start reading as it should.

Thoughts, anyone? Another possibility is that there is NO signal coming from the new sender, and hence a false 0 pressure reading. ?
.Well, one thing I decided to look for tonight is whether, when the ignition is turned off, the needle on the gauge falls even further to the left or not. It in fact does, but only a minute amount, since there is apparently only that much “room” left on the gauge. This tells me then that the gauge is indeed getting some input from the sender (vs. just “dead”), but just not enough to bring the needle up to the mid-way reading. This in turn makes me wonder whether there is a ground, short or break in the new sender, perhaps in the wire part of same (assuming that is part of the new sender, as I know the old wire was in good shape). btw, earlier in the night when I fired the car up the needle actually moved up to the "2" position on the gauge, but then slowly sunk back down to far left in the red warning zone.
.I’m beginning to think my “bad wire” theory is in fact correct. I noticed tonight when I returned from the store that, after I shut the ignition off, the needle moved slightly to the usual “far left” position it was doing as before. However … out of curiosity, I then restarted the car and was surprised to see that the needle did not move to the right at all. This time instead it remained at the same position it was in when the car was off.