Malfunctionig oil light and buzzer.

[Piratepete]

Hi Guys
The previous owner had disconnected these by unplugging the printed circuit plug at the top  back of the speedo. He relied on the pressure gauge.
I've plugged it back in and get the following results. Ignition ON - oil light flashes. Start engine - oil light goes out. Then after a couple of minutes the oil light flashes and the warning buzzer sounds. Oil pressure is very good.
Any ideas?
Cheers!
Pete
1990 T25 2.1DJ Holdsworth Villa 3

[AngeloEvs]

Is the buzzer sounding with engine at idle?   The buzzer should only sound when above 2000 RPM unless ss the DOPs PCB is faulty.

[Piratepete]

Hi Angelo
If I start the engine and keep it at low revs (900rpm), the oil light goes out and the buzzer doesn't sound. It's only when I increase the revs, I guess to 2000 rpm that the oil light flashes and the buzzer goes off and won't stop.
Pete

[ajsimmo]

The DOP system isn't seeing the required 0v (earth) signal from the 2nd switch. Bad/missing switch, broken wire, or bad connection at dash.

Sent from my ONEPLUS A3003 using Tapatalk

[AngeloEvs]

 On a healthy Engine, the high pressure switch should connect to earth with the engine cold and idling. Has the switch been removed so that a oil pressure gauge sender can be fitted?

You will find a lot of info in the WIKI or by searching for 'buzzer of doom' in the technical section of the forum regards location of the high oil pressure switch, types that have different oil pressure settings and wiring faults that others have found.

 

[Piratepete]

Thanks Guys
You've given me plenty to check in to. If the pressure switch has been replaced by a sender for the gauge, I'll rejig the connections so that the other switch does function or maybe fit a T piece. 

Pete

[Mocki]