• Perform the Diagnostic System Check prior to using this diagnostic procedure:Diagnostic System Check - Vehicle
• Review the description of Strategy Based Diagnosis:Strategy Based Diagnosis
• An overview of each diagnostic category can be found here:Diagnostic Procedure Instructions

For an overview of the component/system, refer to:Starting System Description and Operation

Starting and Charging Schematics

Master Electrical Component List

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

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Control Module References

1. Ignition » On / Vehicle » In Service Mode

Note: Steps 2 and 3 are for vehicles equipped with a push button ignition switch. If the vehicle is not equipped with a push button ignition switch, continue to step 4.

2. Brake Pedal»Applied

Verify the scan tool parameter:Brake Pedal Position Sensor.=Active

• If not the specified value

  Refer to Stop Lamps Malfunction for diagnosis of the B22 Brake Pedal Position Sensor.

• If the specified value
3. Brake Pedal»Released

   Verify the scan tool parameter:Brake Pedal Position Sensor.=Inactive

• If not the specified value

  Refer to Stop Lamps Malfunction for diagnosis of the B22 Brake Pedal Position Sensor.

• If the specified value
4. Ignition » On / Vehicle » In Service Mode
5. Verify that no DTCs are set.
• If any DTC is set

  Refer to:Diagnostic Trouble Code (DTC) List - Vehicle

• If no DTC is set
6. {If available}Verify the scan tool parameter:Park/Neutral Position Switch=Park
• If not the specified state

  {If available}Refer to:Shift Indicator Indicates Wrong Gear Selection

• If the specified state
7. Ignition»Crank

   Verify the scan tool parameter:

• { Without BTM and/or ATH/ATS }5V Ignition Switch=Crank Request&Accessory=Inactive
• { With BTM and/or ATH/ATS }Engine Control Module—Power Mode=Crank Request
• If not the specified state

  Refer to:Power Mode Mismatch

• If the specified state
8. Verify the scan tool parameter:Crankshaft Position Active Counter=Does not Increment
• If the parameter value increments

  Replace the component:B26 Crankshaft Position Sensor

• If the parameter value does not increment
9. Verify the component works as specified:Engine»Rotate(s)
• If the component does not work as specified

  Verify the following conditions do not exist:

1. Accessory drive belt component—Seized
2. Engine—Seized
• If the component works as specified
10. Ignition»Crank

    Verify the component works as specified:

• M64 Starter Motor=Activated—Rotate(s)
• Engine=Cranking
• {M64 Starter Motor¿Rotate(s)&Starter Pinion¿Clicks}If the component does not work as specified

  Refer to: Circuit/System Testing

• If the component works as specified
11. All OK.

1. Verify a test lamp turns On between the test points:B+ circuit terminal 1 or A@M64 Starter Motor&Ground
• If the test lamp does not turn On and the circuit fuse is OK
1. Ignition/Vehicle » Off & Remove » Test lamp
2. Test for less than 2 Ω between the test points:B+ circuit terminal 1 or A@M64 Starter Motor&Output terminal@Fuse
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Verify the fuse is OK and there is voltage at the fuse.
• If the test lamp does not turn On and the circuit fuse is open
1. Ignition/Vehicle » Off & Remove » Test lamp
2. Test for infinite resistance between the test points:B+ circuit terminal 1 or A@M64 Starter Motor&Ground
• If less than infinite resistance » Repair the short to ground on the circuit.
• If infinite resistance
3. Replace the component:M64 Starter Motor
• If the test lamp turns On

Note: It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

2. Ignition/Vehicle & All vehicle systems » Off
3. Remove the component:KR27 Starter Relay
4. Test for less than 10 Ω between the test points:Ground circuit terminal 86&Ground
• If 10 Ω or greater
1. Disconnect the ground connection:Ground Connection@The other end of the circuit
2. Test for less than 2 Ω between the test points:Ground circuit terminal 86&Ground terminal@The other end of the circuit
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Repair the open/high resistance in the ground connection.
• If less than 10 Ω
5. Connect a test lamp between the test points:Control circuit terminal 85&Ground circuit terminal 86
6. Ignition » On / Vehicle » In Service Mode
7. Perform the appropriate scan tool control function:
• {If available}Starter Motor Relay»On and Off
• {If available}Starter Relay»On and Off

  Verify the test lamp turns On and Off.

• If the test lamp is always Off
1. Ignition/Vehicle » Off & Remove » Test lamp
2. Disconnect the electrical connector:K20 Engine Control Module
3. Test for infinite resistance between the test points:Control circuit terminal 85@Relay Socket&Ground
• If less than infinite resistance » Repair the short to ground on the circuit.
• If infinite resistance
4. Test for less than 2 Ω between the test points:Control circuit terminal 85@Relay Socket&The other end of the circuit@Control module harness
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Replace the component:K20 Engine Control Module
• If the test lamp is always On
1. Ignition/Vehicle » Off & Remove » Test lamp
2. Disconnect the electrical connector:K20 Engine Control Module
3. Ignition » On / Vehicle » In Service Mode
4. Test for less than 1 V between the test points:Control circuit terminal 85@Relay Socket&Ground
• If 1 V or greater » Repair the short to voltage on the circuit.
• If less than 1 V » Replace the component:K20 Engine Control Module
• If the test lamp turns On and Off
8. Verify a test lamp turns On between the test points:B+ circuit terminal 30&Ground
• If the test lamp does not turn On and the circuit fuse is OK
1. Ignition/Vehicle » Off & Remove » Test lamp
2. Test for less than 2 Ω between the test points:B+ circuit terminal 30@Relay Socket&Output terminal@Fuse
• If 2 Ω or greater » Repair the open/high resistance in the circuit.
• If less than 2 Ω » Verify the fuse is OK and there is voltage at the fuse.
• If the test lamp does not turn On and the circuit fuse is open
1. Ignition/Vehicle » Off & Remove » Test lamp
2. Test for infinite resistance between the test points:B+ circuit terminal 30&Ground
• If less than infinite resistance » Repair the short to ground on the circuit.
• If infinite resistance
3. Disconnect the electrical connector:X1@M64 Starter Motor
4. Test for infinite resistance between the test points:Control circuit terminal 87@Relay Socket&Ground
• If less than infinite resistance » Repair the short to ground on the circuit.
• If infinite resistance
5. Replace the component:M64 Starter Motor
• If the test lamp turns On
9. Momentarily connect a 40 A fused jumper wire between the test points:B+ circuit terminal 30&Control circuit terminal 87

   Verify the component does not turn On and Off when connecting and disconnecting the jumper wire:M64 Starter Motor

• If the component turns On and Off

  Test or replace the component:KR27 Starter Relay

• If the component does not turn On and Off
10. Ignition/Vehicle & All vehicle systems » Off
11. Install the component:KR27 Starter Relay
12. Disconnect the electrical connector:X1@M64 Starter Motor
13. Connect a test lamp between the test points:Control circuit terminal 1 or A&Ground
14. Ignition » On / Vehicle » In Service Mode
15. Perform the appropriate scan tool control function:
• {If available}Starter Motor Relay»On and Off
• {If available}Starter Relay»On and Off

  Verify the test lamp turns On and Off.

• If the test lamp is always Off

  Repair the open/high resistance in the circuit:Control Circuit

• If the test lamp is always On

  Repair the short to voltage on the circuit:Control Circuit

• If the test lamp turns On and Off
16. Test or replace the component:M64 Starter Motor

1. Ignition/Vehicle » Off
2. Remove the appropriate component:
• KR27 Starter Relay
3. Test for 70 to 110 Ω between the test points:Component terminal 85&86
• If not between 70 and 110 Ω

  Replace the appropriate component:KR27 Starter Relay

• If between 70 and 110 Ω
4. Test for infinite resistance between the test points:
• Component terminal 30&85
• Component terminal 30&86
• Component terminal 30&87
• Component terminal 85&87
• Component terminal 86&87
• If less than infinite resistance

  Replace the appropriate component:KR27 Starter Relay

• If infinite resistance
5. Connect a 3 A fused jumper wire between the test points:Component terminal 86&12 V

   Connect a jumper wire between the test points:Component terminal 85&Ground

6. Test for less than 2 Ω between the test points:Component terminal 30&87
• If 2 Ω or greater

  Replace the appropriate component:KR27 Starter Relay

• If less than 2 Ω
7. All OK.

Perform the Diagnostic Repair Verification after completing the repair:Diagnostic Repair Verification

• Starter Solenoid Cable Replacement
• Electrical Relay Replacement
• Starter Replacement
• For control module replacement, programming, and setup refer to:Control Module References