Engine Cranks Slowly

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 (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
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 (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Ignition OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12.0-15.0 V.

• If not within the specified range, refer to Battery Charging (Procedures).

2. Remove the drive belts. Refer to Drive Belt Tensioner Replacement (), Drive Belt Replacement () for the LLT engine, Drive Belt Tensioner Replacement - Accessory (Service and Repair) or Drive Belt Replacement - Accessory (Drive Belt Replacement - Accessory) for the L99/L53 engines.
3. Place the S39 ignition switch to the CRANK position.

• If the engine cranks normal, inspect the engine and belt drive system for mechanical binding, seized engine, or seized generator, etc.

4. Test for less than 0.5 V between the positive battery cable and terminal A X2 at the M64 starter motor as the S39 ignition switch is placed to the CRANK position.

• If greater than the specified value, replace the positive battery cable.

5. Test for less than 0.5 V between the negative battery cable and the starter motor case as the S39 ignition switch is placed to the CRANK position.

• If greater than the specified value, replace the negative battery cable.

6. If all circuits test normal, replace the M64 starter motor.

Repair Instructions

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

* Battery Positive Cable Replacement (Battery Positive Cable Replacement)
* Battery Negative Cable Replacement (Battery Negative Cable Replacement)
* Starter Replacement (Service and Repair)