acaie Posted April 2, 2019 Report Share Posted April 2, 2019 The oil pressure light switch on my Grinall TR7v8 has failed - it's dripping oil everywhere. It's an SD1v8 with a 3 terminal switch with only 2 wires going to it.The 3 terminal switches are difficult and expensive to get. Looking at the TR7 wiring diagram I think I could use a 1 terminal switch. Does anyone know the part number for a 1 terminal switch which will fit? Quote Link to post Share on other sites
UlsterTR7 Posted April 6, 2019 Report Share Posted April 6, 2019 (edited) Not wanting to appear pedantic - I don't know the TRs well enough yet - but do you mean the sensor rather than the switch? If I know that's what you mean I can look for an alternative more easily. Edited April 6, 2019 by UlsterTR7 Quote Link to post Share on other sites
acaie Posted April 7, 2019 Author Report Share Posted April 7, 2019 It's a switch operated by the oil pressure - it turns off the oil pressure warning light. Quote Link to post Share on other sites
barkerwilliams Posted April 8, 2019 Report Share Posted April 8, 2019 . I don't know the TR7 but Jeeps use a three wire switch https://www.ebay.co.uk/itm/56028807AA-Oil-Pressure-Switch-Car-Oil-Pressure-Sensor-for-Dodge-Jeep-Chrysler/143094700901?hash=item21511bdb65:g:I8kAAOSwzrBawZET Some Cummins Engines use a three wire switch, and I have vague memories of a BMW three wire switch. Hope it helps, Alan Quote Link to post Share on other sites
David James Posted April 9, 2019 Report Share Posted April 9, 2019 From memory the three connection oil pressure switch on the Rover SD1 etc is used to indicate low oil pressure but also acts as a safety device in an accident when the engine stops and the ignition is left on. The switch senses no oil pressure when the engine stops and cuts the power to the fuel pump. When starting the engine power is fed to the pump via the switch fed from the starer solenoid. As soon as the starer is released the pump will continue to be powered and the engine run if there is enough oil pressure , or if no oil pressure, the pump will not get power. ie. not run the pump. Having wired X2 TR7 V8s of mine in the past, on one I added wiring to the 7 harness to be able to have the three connection safety facility of no oil pressure, no feed to the fuel pump, and on the other fitted the single terminal switch using just one connection as standard TR7. Hope this helps? Regards David Quote Link to post Share on other sites
tim_trinda Posted April 9, 2019 Report Share Posted April 9, 2019 I used one of these https://rimmerbros.com/Item--i-STC4104P as I was only using the wire to the oil pressure light anyway Regards Tim Quote Link to post Share on other sites
acaie Posted April 10, 2019 Author Report Share Posted April 10, 2019 I've ended up with FAE 11320. This has a 1/4 x 18 NPTF taper thread and fits very nicely. I believe the STC1404 has a 1/2 UNF and fits other or later engines. Thanks to all for your help. Al Quote Link to post Share on other sites
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