oil pressure sending unit

[leanburn]

how do you test the sending unit? if i ground the wire the light comes on. but my light does not come on when engine not running  key in acc posistion, should it?

[dodj]

It should in the run position. If you have a meter, measure the resistance from the switch connection to ground. It should be low, a few ohms or less. Oil pressure opens the switch. 

[leanburn]

i done what you said and it's opposite of what i need, i hooked up my air compressor to it and it will only read with pressure. thanks i will look for another one.

[dodj]

It's possible you have a sending unit for a gauge, rather than a light. Is it about an inch and a half high and an inch around or is it smaller than that?

[leanburn]

that's it. i didn't specify guage or light but i will now. thanks for the help.