Circuit/System Verification

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

Ignition OFF, measure and record the battery voltage at the terminals. The voltage should be between 12.0 - 15.0 V.
- If not within the specified range, refer to Battery Inspection/Test .
Verify that a test lamp illuminates between the starter motor B+ terminal B X1 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 0.5 V between the positive battery cable and terminal B X1 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 0.5 V between the negative battery cable and the 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 4.8L or 5.3L engines
- Air Conditioning Compressor Belt Replacement for the 4.8L or 5.3L engines
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 starter motor.