GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

When the ignition switch is placed in the START position, a discrete signal is supplied to the body control module (BCM) notifying it that the ignition is in the START position. The BCM then sends a message to the engine control module (ECM) that crank has been requested. The ECM then verifies that the transmission is in Park or Neutral, or that the clutch pedal is pressed. If it is, the ECM then supplies 12 volts to the control circuit of the STRTR relay. When this occurs, battery voltage is supplied through the switch of the STRTR relay to terminal A X1 of the starter solenoid.

Reference Information

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Starting System Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12.6 and 15.0 volts.
  2. If not within the specified range, refer to Charging System Test .
  3. Verify that the battery cables are clean and tight.
  4. If the battery cables are not within specified range, refer to Fastener Tightening Specifications .
  5. Transmission in Park or clutch pedal pressed, turn the ignition switch to the start position. The starter solenoid should click.
  6. If starter solenoid does not click, , refer to Starter Solenoid Does Not Click .
  7. Remove the drive belt, refer to Drive Belt Replacement for the 2.9L engine, or Drive Belt Replacement for the 3.7L engine.
  8. Turn the ignition switch to the START position.
  9. If the engine cranks, inspect the engine and belt drive system for mechanical binding, seized engine, or seized generator, etc.
  10. Attempt to rotate the engine crankshaft, using an appropriate tool.
  11. If the engine crankshaft cannot be rotated, refer to Engine Will Not Crank - Crankshaft Will Not Rotate for the 2.9L engine, or Engine Will Not Crank - Crankshaft Will Not Rotate for the 3.7L engine.
  12. Ignition in START, test for less than 0.5 volts between the positive battery cable and terminal A X2 at the solenoid.
  13. If greater than the specified range, replace the positive battery cable.
  14. Ignition in START, test for less than 0.5 volts between the negative battery cable and the starter motor case.
  15. If greater than the specified range, replace the negative battery cable.
  16. If all circuits test normal, replace the starter motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Battery Positive and Negative Cable Replacement
    •  Starter Motor Replacement