[Mgs] Oil Pressure question

[Paul Hunt]

What year, and electric or mechanical?  From my schematics the oil pressure
gauges in 74 and 76 are mechanical and not electric (which only went up to 71)
so there is no sender and it can only be the gauge or a problem with pressure
(correct oil level doesn't automatically mean you will have correct pressure)

If electric gauge I'd guess it was the sender, as they incorporate a pressure
detector as well as a voltage regulator.  Easy to check, just measure the
voltage on the white/brown.  Ordinarily it should be pulsing between 0v and
battery voltage like the voltage regulator for the fuel gauge, the duty cycle
changing as the pressure changes.  A low duty cycle i.e. long off periods
(showing battery voltage) and short on period (0v) will cause a low gauge
reading, as will a high-resistance to ground during the on-period i.e. not
dropping to zero.

PaulH.
  ----- Original Message -----
  Anybody have an idea where the fault lay when the oil pressure gauge
  indicates only the transition pressures?