How do I check the oil pressure switch on my Onan?
With Onan running, jumper terminal #1 to Terminal # 12 (right side of switch on board). If all is well, the Onan should stop in 3 to 4 seconds. This is a very important safety function & should be verified before you smoke your engine do to lack of Oil. The GMC Onan oil pressure switch must be a “Normally Closed” type to function properly with the control board. Take the original Pressure switch to you local Auto parts store & they can match it with the proper switch arrangement (contact closed w/o pressure… measure it at the counter).
