When the Ignition switch is placed in the RUN position B+ is supplied battery isolator control circuit. The battery isolator is used to isolate the auxiliary and primary batteries. When the Ignition is OFF only the auxiliary battery is being used so that the primary battery is not being discharged causing a no start condition. When the engine is running the generator(s) recharge all the batteries to maintain system voltage and keep the batteries charged.

Schematic Reference

Auxiliary Battery Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Starting System Description and Operation

Electrical Information Reference

Verify that the auxiliary/accessory connection is installed on the correct battery isolator stud.

1. Verify that IP- 1 fuse block AUX WIRE fuse 5 is not open.
2. Ignition ON, verify a test lamp illuminates between the battery isolator B+ circuits terminals E- ABAT- PBAT- A and ground.

⇒	If the test lamp does not illuminate, test the affected circuit for a short to ground or an open/high resistance.

3. Ignition OFF, verify a test lamp only illuminates between the battery isolator B+ circuits terminals ABAT- PBAT and ground.

⇒	if the test illuminated on terminals A and or E with Ignition OFF, replace the battery isolator.

⇒	If the did not illuminate terminals ABAT- PBAT test the fusible links between primary/aux batteries and the battery isolator for an open.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.