# Oil pressure sensor working in reverse? OBS Ford **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [March 25, 2019, 10:53pm UTC](https://community.cartalk.com/t/oil-pressure-sensor-working-in-reverse-obs-ford/137242 "2019-03-25T22:53:00Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Hobby\_welder](https://avatars.discourse-cdn.com/v4/letter/h/3bc359/32.png) [@Hobby\_welder](https://community.cartalk.com/u/Hobby_welder)\ **Post date:** [March 25, 2019, 10:53pm UTC](https://community.cartalk.com/t/oil-pressure-sensor-working-in-reverse-obs-ford/137242/1 "2019-03-25T22:53:01Z")
Well im back again folks. This time I think I actually have a bad wire! (1993 Ford F250 M/T 351w/5.8l 4x4) So, I had a new oil pressure sensor put in when all the fluids were changed out. The reason for the new one is the old one, on occasion would spaz out and bounce around like crazy. Now the new one, will read when the key is on, engine off. The moment the engine is on its dead and shows nothing. The photo is key on engine off. So is this a bad wire? Is the new unit wrong? I don’t think the wire can be put in backwards but… ![image](https://global.discourse-cdn.com/cartalk/original/2X/d/dca6c0d72cffea9ef0ecdd58fb44f40a855a6e20.jpeg) ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [March 25, 2019, 11:37pm UTC](https://community.cartalk.com/t/oil-pressure-sensor-working-in-reverse-obs-ford/137242/2 "2019-03-25T23:37:33Z")
With all the tape on the dash and around the steering column? I’m gonna guess it’s the instrument cluster. ![](https://global.discourse-cdn.com/cartalk/original/2X/d/ddaf71350be10b62b7a5eff19230c2b463a27fcc.jpeg) Tester ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [March 25, 2019, 11:48pm UTC](https://community.cartalk.com/t/oil-pressure-sensor-working-in-reverse-obs-ford/137242/3 "2019-03-25T23:48:54Z")
Sounds like you installed an oil pressure switch for a warning light, closed circuit with no oil pressure, open circuit when running. Take a look at the pictures on rockauto, the sending unit for the oil pressure gauge is larger than the on for the warning light. ---
**Author:** ![Hobby\_welder](https://avatars.discourse-cdn.com/v4/letter/h/3bc359/32.png) [@Hobby\_welder](https://community.cartalk.com/u/Hobby_welder)\ **Post date:** [March 25, 2019, 11:49pm UTC](https://community.cartalk.com/t/oil-pressure-sensor-working-in-reverse-obs-ford/137242/4 "2019-03-25T23:49:40Z")
Oh probably. It wouldn’t surprise me all things considered. The tape has nothing to do with that though. I can’t get the right clips in for trim so its taped. Its only come off for the steering column replacement. ---
**Author:** ![Hobby\_welder](https://avatars.discourse-cdn.com/v4/letter/h/3bc359/32.png) [@Hobby\_welder](https://community.cartalk.com/u/Hobby_welder)\ **Post date:** [March 25, 2019, 11:51pm UTC](https://community.cartalk.com/t/oil-pressure-sensor-working-in-reverse-obs-ford/137242/5 "2019-03-25T23:51:04Z")
Huh. That could be. I ordered the wrong temp sensor/sender so I could probably bet money on it. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [March 26, 2019, 3:16am UTC](https://community.cartalk.com/t/oil-pressure-sensor-working-in-reverse-obs-ford/137242/6 "2019-03-26T03:16:46Z")
An oil pressure switch for an idiot light is just an on/off switch and will either measure less than 1 ohm, or over 1 million ohms. An oil pressure sender for a dash gauge is a resistor that varies according to the oil pressure, and will probably measure resistances in the 100 ohms to 10 K ohm ranges.