Last night oil gauge started dropping to bottom of gauge tripping check gauges light and chime. Since it was raining I'm thinking loose connection. My question Where is the sensor? I tried to find it on the parts lookup. It is listed as number 12 but picture only goes to 11. Want to clean the connection. 

underneath the ECM on the driver's side

Thanks. I'll get after it after my coffee. Got to wait for garage to warm up.

Just finished cleaning. Didn't find much wrong but cleaned and grease. Will see next time it rains. Thanks for the info.

Follow up, sensor still acting up. Got new one from Geno's . Installed yesterday, also cleaned map sensor and wiring to boost fooler. So back to waiting for the rain again.

Did you make sure there is no damage to back side where the wires go in to make the actual plug?

Crank sensor was doing the exact same thing to me in the rain when looking at it nothing seams wrong but with a bright flashlight from either side of the plug deep inside you should be able to see green dust or a white gray if so replace the connector.

Edited December 30, 20168 yr by WiscoRedkneck

WiscoRedneck, Yes I did check the only thing I noticed was when shined light from sensor side I could see light on wire side. So put silicone on wire side and die-electric grease on sensor side. I cleaned plug as best I could. Yesterday it got warm enough to melt some snow and I went out for a 2 hour drive on wet roads and the problem did not occur. Will see when it rains next week. I do see a little higher oil pressure with the new sensor. 

Well no went for a drive in the rain problem still persists. Going nuts.

Another update. After reading articles here one thing I read was to do a "wiggle" test on the wiring to try and recreate problem. Tried could not recreate but got a small spark when oil pressure sensor wires touched the fitting to the lift pump. So tear down stuff on side of engine to reach and work on wires. Did not find any rub spot or break in wire, so wrapped each wire with tape, then all three together, then put split loom on. Did same to map sensor, put truck back together go for a ride. Roads not quite as wet as this morning but no problem with sensors. Back to waiting for a good rain to drive in.  

Hmm sounds like you have damaged wiring those can be painful, do you have a multimeter?  You need to find all the damaged wires and replace with new of the correct gauge using heat shrink splices or similar water proof connection.  It's tedious but can be fairly cheap to repair yourself 

14 hours ago, WiscoRedkneck said:

Hmm sounds like you have damaged wiring those can be painful, do you have a multimeter?  You need to find all the damaged wires and replace with new of the correct gauge using heat shrink splices or similar water proof connection.  It's tedious but can be fairly cheap to repair yourself 

Your right there was a damaged wire.

Did repairs and got to test drive it in the rain , so far no more trouble. Thanks for the advice and replies.