Circuit/System Verification

Ignition OFF, measure and record the battery voltage at the C1 terminals. The voltage should be between 12.0-15.0V.
- If not within the specified range, refer to Battery Inspection/Test .
Verify that a test lamp illuminates between the M64 starter motor B+ terminal AX2 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
Test for less than 0.5V between the positive battery cable and terminal AX2 at the M64 starter motor as ignition is switched to start position.
- If greater than the specified value, replace the positive battery cable.
Test for less than 0.5V between the negative battery cable and the M64 starter motor case as ignition is switched to start position.
- If greater than the specified value, replace the negative battery cable.
Remove the drive belts. Refer to one of the following:
- Drive Belt Replacement - Accessory for the 6.2L or 7.0L engine
- Drive Belt Replacement for the 3.6L engine
Ignition start, verify the engine does not crank normal.
- If the engine cranks normal, inspect the engine and belt drive system for mechanical binding, seized generator etc.
If all circuits test normal, replace the M64 starter motor.