Circuit/System Testing

LAT, LY7, or LCS Engine

1. Verify that a test lamp illuminates between the generator B+ terminal 1 X2 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
2. Ignition OFF, disconnect the harness connector at the generator.
3. Ignition ON, engine OFF, test for less than 1 V between the generator turn on signal circuit terminal 1 X1 and ground.
   • If greater than the specified range, test the generator turn on signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Engine running, command the GEN L-Terminal ON to 85% with a scan tool. Test for greater than 3.5 V between the generator turn on signal and ground.
   • If less than the specified range, test the generator turn on signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
5. If the circuit tests normal, replace the generator.

LE5 or LZ4 Engine

1. Verify that a test lamp illuminates between the generator B+ terminal 1 X2 and ground.
   • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
2. Ignition OFF, disconnect the X1 harness connector at the generator.
3. Ignition ON, test for 4.5-5.5 V between the control circuit terminals 1 X1 and ground.
   • If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
   • If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal replace the ECM.
4. If the circuits test normal, replace the generator.