ELECTRONIC TECHNICIAN (ET) TROUBLESHOOTING - Continued
Electrical Power Supply Circuit Test.
System Operation Description:
Use this procedure and Figure 3 to troubleshoot any suspect problems with the electrical supply to the engine
Electronic Control Module (ECM). This procedure covers the following diagnostic code:
168-02 System voltage intermittent/erratic
168-03 System voltage above normal
168-04 System voltage below normal
A signal from the ENGINE CONTROL switch (ESC) is provided to Generator Set Control (GSC) interface to the
ECM and tells the ECM the position of the ECS. When the ECM senses battery voltage to the GSC interface to
the ECM, the ECM will power up. The GSC receives battery voltage when the ECS is in the AUTO, MANUAL
START or COOL DOWN/STOP positions. If the voltage is removed from the GSC, the ECM will power down.
Cycling power to the GSC interface to the ECM will reset the ECM. The electrical power for the engine comes
through the CB4 circuit breaker and the Slave Relay to the battery terminals on the ECM. The presence of three
+Battery connections and three -Battery connections to the ECM reduces harness resistance. All of these
connections must be complete in order to ensure proper engine operation.