Dodge D350 1990 - Coolant Heater - Check; Coolant Temperature Sensor - Check; Oil Pressure Switch;Sending Unit - Check

Electrical System
DODGE Turbo Diesel
Diagnosing Electrical Malfunctions
Page 8-11
Oil Pressure Switch/Sending Unit - Check
Remove the pressure switch, install a gauge, start the engine >^
and measure oil pressure. Minimum oil pressure:
Idle 69kPa [10 psi]
Rated Speed 207 kPa [30 psi]
Note: The Pressure switch is set to actuate when oil pressure
drops to 55 kPa [8 PSI]. The pressure switch wilt activate a
Low Pressure Warning Light on the dash of the truck.
Coolant Temperature Sensor - Check
Replace the sensor and rerun engine to confirm the
temperature.
Coolant Heater - Check
When operating, the engine block heater should make an
audible sound and the adjacent parts should be warm to the
touch.
The heater will operate continuously when plugged into the
correct voltage electrical socket (110 volt A.C, 6.5 amp).
Operate only when the ambient temperature is below 4°C [40°
F].
4°c;