On an '89 740 B230F engine. Where is the oil pressure sending unit? The oil light is flickering and I want to test the switch.

Others have correctly id'd location. Sensor is a plastic unit crimped into a metal (can't remember is steel or Al) housing. Don't bother testing the switch, just replace it. Mine was the cause of a leak that took forever to find. Idle oil pressure wouldn't cause leakage. Normal running oil pressure would cause bad leak, enough to make it hard to id. So after several cycles of cleaning and looking, then driving the car around and losing lots of oil, I had to actually crawl under the car and have wifey rev the engine with me under the car. (Is that love or what? I trust her.) Only then could I pinpoint the leak.

Point is that the plastic insert design isn't the most robust. On a 1989 700, you may as well replace, then check for light and move on to other causes if still having problem.

HTH,

someguyfromMaryland

Russ:
On the B230 it is next to the oil filter on the passenger's side of the engine.
buena suerte, G.Lo.

Raidman,

Thanks that is what I suspected. However the wire leading into the sensor looks to be NON removable. Since the wiring runs along the front of the oil pan and disapears into the harness, is the wire lead supposed to be disconnected out of the sensor or does the sensor have the pig tail wire like an O2 sensor?

Bob is corect..the wire is encased in a plastic tube-type connector that plugs onto the sensor.
Buena suerte, el Raidman.

The wire unplugs from the sensor. You squeeze the tabs on the white round plastic insulator and pull it out. Long needlenose plier is helpfull.