Starting and Charging: Testing and Inspection

Engine Cranks Slowly

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Reference Information

Schematic Reference

Starting and Charging Schematics [1][2]Electrical Diagrams

Connector End View Reference

Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)

Description and Operation

Starting System Description and Operation Description and Operation

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. 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 Battery Inspection/Test.

2. Remove the drive belts. Refer to one of the following:

* Drive Belt Replacement for the 4.3L engine

* Drive Belt Replacement for the 6.6L Diesel engine

* Drive Belt Replacement - Accessory Drive Belt Replacement - Accessory for the 4.8L or 5.3L engines

* Air Conditioning Compressor Belt Replacement Air Conditioning Compressor Belt Replacement for the 4.8L or 5.3L engines

3. 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 engine, or seized generator.

4. 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.

5. 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.

6. 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.

7. If all circuits test normal, replace the starter motor.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Battery Positive Cable Replacement (V8) Service and RepairBattery Positive Cable Replacement (LGH - Auxiliary) Service and RepairBattery Positive Cable Replacement (V6) Service and RepairBattery Positive Cable Replacement (LGH - Primary) Service and Repair

* Battery Negative Cable Replacement (V6) Service and RepairBattery Negative Cable Replacement (LGH - Primary) Service and RepairBattery Negative Cable Replacement (V8) Service and Repair

* Starter Replacement (Diesel) Starter Replacement (Diesel)Starter Replacement (V8) Starter Replacement (V8)Starter Replacement (V6) Starter Replacement (V6)