Engine Protection System Circuit Diagnosis

Circuit Description
The engine protection system utilizes a separate control module and independent sensors to monitor the oil pressure, coolant temperature and coolant level. With each engine start up, the system self tests with an alarm and light display for 3 seconds. When the engine is started, the alarm and light display will cancel as oil pressure rises. When a malfunction occurs (engine coolant overheat, low coolant level, or low oil pressure), the engine protection module will open the engine shut off solenoid (ESO) located on the injector pump 30 seconds after the condition is detected.

Diagnostic Aids
The following conditions may cause a no start or false alarms:
^ If the engine protection module in-line fuse, located under the dash near the module is open, the engine will not start.
^ The engine protection module ground has a poor connection.
^ A wire to the coolant level sensor that is broken inside the insulation may cause an intermittent alarm

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
2. This step verifies the engine protection system is functioning.
8. This step checks the low oil pressure circuit for a short to ground.
9. This step checks the high engine temperature circuit for a short to ground.
13. This step checks the low coolant sensor circuit for an open.