It is not a good thing, but I have been running my engine
with with limited instrumentation. Now, troubleshooting these circuits has now come back to the top of my to-do list.
In the beginning: Judging by the re-configuration of the wiring
, the PO has tried to change / upgrade the oil
pressure and the engine
temperature circuits. From the drawings I have, the original sensors for both the oil
pressure and temp were probably on/off switch type sensors used to activate the alarm
annunciator. With these sensors, there were probably no display gauges.
What I have now: Both the oil pressure and temp sensors have analog outputs to drive their respective meter gauges.
-Oil Pressure.. The oil pressure gauge operates as expected, but the alarm
annunciator does not sound when the oil pressure is low.
-Temperature.. The temp display barely comes on scale when the engine is at operating temperature.
What I have found so far:
-The annunciator is BAD. The alarm will not sound when activated from any of the input sources. I need to find a replacement annunciator.
-The voltage across the temp sensor changes as the engine warms; Thus, it appears to be good. (The thermostat has already been changed.. no help.)
-I am not sure if the temp display is even the correct one for this application.
The engine is a raw water
3GMD. The thermostat opens at about 135F, so it is a cool running engine. It would help if I knew the typical full-scale operating current
for the temp display gauge. At least then I could set up a test circuit to check the meter movement.
Any suggestions on where I might find a used annunciator (The engine is 30 years old.) or for additional troubleshooting checks will be appreciated.