Starter Malfunction (Except LM2)

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. Diagnostic Fault Information

Circuit Number	Circuit Function	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performan
2	B+	1	1	—	—
625	Control	P0616	P0615	P0617	—
4325	Control	P26E5	P26E4	P26E6	—
6	Control	1	1	3	—
4358	Control	2	2	4	—
6550	Ground	—	P0615, P26E4	—	—
1. Upon crank request the Starter Drive will engage, but the starter motor will not spin. 2. Upon crank request the starter motor will spin , but the Starter Drive will not engage. 3. The Starter motor will spin all the time. 4. The Starter Drive will be engaged all the time.

Circuit/System Description When the ignition switch is placed in the START position, a signal is supplied to the K9 Body Control Module notifying it that the ignition is in the START position. Once a valid security message is received the K9 Body Control Module sends a message to the K20 Engine Control Module that crank has been requested. The K20 Engine Control Module verifies the security information is valid and that the transmission is in Park/Neutral. If it is, the K20 Engine Control Module supplies 12 V to the control circuit 625 of the KR27 Starter Relay, when this occurs, battery voltage is supplied through the switch of the KR27 Starter Relay to circuit 6 to engage the starter motor solenoid to allow the motor to spin. The K20 Engine Control Module also supplies 12 V to the control circuit 4325 of the KR27C Engine Restart Relay, when this occurs, battery voltage is supplied through the switch of the KR27C Engine Restart Relay to circuit 4358 to engage the starter motor pinion actuator solenoid, this allows the pinion actuator to kick out and engage the pinion with the flywheel. Diagnostic Aids If the condition is a no crank or intermittent no crank concern and the X50B Battery Distribution Engine Compartment Fuse Block F3BA 400 Amp Fuse is NOT open, remove the starter B+ stud nut and inspect for evidence of electrical arcing or discoloration, reinstall and torque the fastener to specs. If the X50B Battery Distribution Engine Compartment Fuse Block F3BA 400 Amp Fuse for the starter is Open and If a short is not found verify the following: – The circuit must be thoroughly inspected for intermittent chafing and potential routing concerns prior to replacing the starter. – Engine mechanical failures or binding accessory drive belt components may cause excessive cranking amperage and may cause the Fuse to open. Refer to: 5.3L L84, 6.2L L87 Symptoms - Engine Mechanical Reference Information Schematic Reference Starting and Charging Schematics Connector End View Reference Master Electrical Component List Description and Operation Starting System Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

1. Verify the X50B Battery Distribution Engine Compartment Fuse Block F3BA 400 Amp fuse is not open. ⇒ If the Fuse is open Refer to Circuit/System Testing: Starter Motor Test.
2. Ignition ON.
3. Verify the scan tool parameter for the brake pedal position sensor is active with the brake pedal pressed. ⇒ If not the specified value Refer to Stop Lamps Malfunction for diagnosis of the B22 Brake Pedal Position Sensor. ⇓ If the specified value
4. Verify the scan tool parameter for the brake pedal position sensor is inactive with the brake pedal released. ⇒ If not the specified value Refer to Stop Lamps Malfunction for diagnosis of the B22 Brake Pedal Position Sensor. ⇓ If the specified value
5. Verify there are no B315A Transmission Range Control Valve 1 Position Switch system related DTCs. ⇒ If a related DTC is set Refer to Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If a related DTC is not set
6. Verify the scan tool parameters for the B315A Transmission Range Control Valve 1 Position Switch are the correct values. Refer to K71 Transmission Control Module: Scan Tool Information ⇒ If not the specified values Refer to DTC P27EB, P27ED, or P27EE ⇓ If the specified values
7. Ignition Crank, verify the BCM scan tool Power Mode parameter is Crank Request. ⇒ If not the specified state Refer to Power Mode Mismatch ⇓ If the specified state
8. Verify the scan tool Crankshaft Position Sensor RPM parameter does not increment. ⇒ If the parameter value increments Replace the B26 Crankshaft Position Sensor. ⇓ If the parameter value does not increment
9. Verify the Engine will rotate. ⇒ If the engine will not rotate 9.1. Verify all of the components on the drive belt system are not seized. 9.2. Verify the engine is not seized. ⇒ If a Component is seized Repair the condition. ⇓ If a condition is not found
10. Ignition Crank, Verify the starter engages and the engine cranks. ⇒ If the M64 Starter Motor spins and the engine is not cranking Refer to Circuit/System Testing: Starter Drive Test. ⇒ If the M64 Starter Motor does not spin and the starter pinion clicks Refer to Circuit/System Testing: Starter Motor Test. ⇓ If the M64 Starter Motor spins and the engine is cranking
11. A fault is not currently present and may be an intermittent condition. Circuit/System Testing Starter Drive Test
12. Ignition OFF and all vehicle systems off, disconnect the KR27C Engine Restart Relay.
13. Verify a test lamp illuminates between ground circuit terminal 86 and B+. ⇒ If the test lamp does not illuminate 2.1. Repair the open/high resistance on circuit 6550 or ground connection. ⇓ If the test lamp illuminates
14. Ignition on, connect a test lamp between the control circuit terminal 85 and ground.
15. Verify the test lamp turns ON and OFF while commanding the Starter Drive ON and OFF with the scan tool. ⇒ If the test lamp is always OFF 4.1. Test circuit 4325 for a short to ground. ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 4.2. Test circuit 4325 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 4.3. Replace the K20 Engine Control Module. ⇒ If the test lamp is always ON 4.1. Test circuit 4325 for a short to voltage. ⇒ If a short to voltage is found, repair the fault on the circuit. ⇓ If a short to voltage is not found 4.2. Replace the K20 Engine Control Module. ⇓ If the test lamp turns ON and OFF
16. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground. ⇒ If the test lamp does not illuminate and the fuse is good. Replace the X50A Engine Wiring Harness Junction Block ⇒ If the test lamp does not illuminate and the fuse is open 5.1. Test B+ circuit terminal 30 for a short to ground ⇒ If a short to ground is found, replace the X50A Engine Wiring Harness Junction Block ⇓ If a short to ground is not found 5.2. Test circuit 4358 for a short to ground ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 5.3. Replace the M64 Starter Motor. ⇓ If the test lamp illuminates.
17. Test circuit 4358 for open/high resistance ⇒ If an open/high resistance is found, repair the fault on the circuit ⇓ If an open/high resistance is not found
18. Test the X50A Engine Wiring Harness Junction Block between control circuit F1 X3 and terminal 87 at the KR27C  Engine Restart Relay for an open/high resistance. ⇒ If an open/high resistance is found, replace the X50A Engine Wiring Harness Junction Block ⇓ If an open/high resistance is not found
19. Ensure the parking brake is applied and the automatic transmission is in PARK or manual transmission is in NEUTRAL. Momentarily install a 40 A fused jumper between terminal 30 and terminal 87.
20. Verify the Starter Drive clicks. ⇒ If the Starter Drive clicks Replace the KR27C Engine Restart Relay ⇓ If the Starter Drive does not click.
21. Replace the M64 Starter. Starter Motor Test

Note

For intermittent conditions or If there is voltage at the terminal and not at the B+ stud the condition may be caused by a loose connection, remove and inspect the starter nut and stud for arcing or discoloration, reinstall nut and tighten the fastener to specs. Refer to: Fastener Specifications.

1. Verify a test lamp illuminates between the B+ terminal A X2 at the M64 Starter and ground. ⇒ If the test lamp does not illuminate and the circuit fuse is good 1.1. Test the B+ circuit 2 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open or high resistance is not found 1.2. Verify the fuse is good and there is voltage at the fuse. ⇒ If the test lamp does not illuminate and the circuit fuse is open 1.1. Test the B+ circuit 2 a short to ground ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found

Note

Excessive cranking effort due to a engine mechanical or accessory drive belt component condition, may result in a blown F3BA 400A Starter fuse. 1.2. Verify a binding or seized condition does not exist with the engine. ⇒ If a condition exists Refer to: 5.3L L84, 6.2L L87 Symptoms - Engine Mechanical ⇓ If a condition does not exist 1.3. Replace the M64 Starter. ⇓ If the test lamp illuminates

2. Ignition OFF and all vehicle systems off, disconnect the KR27 Starter Relay.
3. Verify a test lamp illuminates between ground circuit terminal 85 and B+. ⇒ If the test lamp does not illuminate 3.1. Repair the open/high resistance on circuit 6550 or ground connection. ⇓ If the test lamp illuminates
4. Ignition on, connect a test lamp between the control circuit terminal 86 and ground.
5. Verify the test lamp turns ON and OFF while commanding the Starter Motor ON and OFF with the scan tool. ⇒ If the test lamp is always OFF 5.1. Test circuit 625 for a short to ground. ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 5.2. Test circuit 625 for an open/high resistance. ⇒ If an open/high resistance is found, repair the fault on the circuit. ⇓ If an open/high resistance is not found 5.3. Replace the K20 Engine Control Module. ⇒ If the test lamp is always ON 5.1. Test circuit 625 for a short to voltage. ⇒ If a short to voltage is found, repair the fault on the circuit. ⇓ If a short to voltage is not found 5.2. Replace the K20 Engine Control Module. ⇓ If the test lamp turns ON and OFF
6. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground. ⇒ If the test lamp does not illuminate and the fuse is good. Replace the X50A Engine Wiring Harness Junction Block ⇒ If the test lamp does not illuminate and the fuse is open 6.1. Test B+ circuit terminal 30 for a short to ground ⇒ If a short to ground is found, replace the X50A Engine Wiring Harness Junction Block ⇓ If a short to ground is not found 6.2. Test circuit 6 for a short to ground ⇒ If a short to ground is found, repair the fault on the circuit. ⇓ If a short to ground is not found 6.3. Replace the M64 Starter. ⇓ If the test lamp illuminates
7. Test circuit 6 for open/high resistance ⇒ If an open/high resistance is found, repair the fault on the circuit ⇓ If an open/high resistance is not found
8. Test the X50A Engine Wiring Harness Junction Block between Control Circuit Terminal B1 X3 and terminal 87 of KR27 Starter Relay for an open/high resistance. ⇒ If an open/high resistance is found, replace the X50A Engine Wiring Harness Junction Block. ⇓ If an open/high resistance is not found
9. Ensure the parking brake is applied and the automatic transmission is in PARK or manual transmission in NEUTRAL. Momentarily install a 30 A fused jumper between terminal 30 and terminal 87.
10. Verify the M64 Starter Motor Spins. ⇒ If the starter spins Replace the KR27 Starter Relay ⇓ If the starter does not spin
11. Replace the M64 Starter. Component Testing Relay Test
12. Ignition OFF, disconnect the appropriate relay.
13. Test for 70–150 Ω between terminals (85 or 1) and (86 or 2). ⇒ If less than 70 or greater than 150 Ω Replace the relay. ⇓ If between 70–150 Ω
14. Test for infinite resistance between the terminals listed below: (30 or 3) and (86 or 2) (30 or 3) and (87 or 5) (30 or 3) and (85 or 1) (85 or 1) and (87 or 5) (86 or 2) and (87 or 5) ⇒ If less than infinite resistance Replace the relay. ⇓ If infinite resistance
15. Install a 3 A fused jumper wire between relay terminal (85 or 1) and 12 V. Install a jumper wire between relay terminal (86 or 2) and ground.
16. Test for less than 5.0 Ω between terminals (30 or 3) and (87 or 5). ⇒ If 5.0 Ω or greater Replace the relay. ⇓ If less than 5.0 Ω
17. A fault is not currently present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Battery Positive and Negative Cable Strap Replacement Starter Solenoid Cable Replacement Battery Distribution Engine Compartment Fuse Block Replacement Electrical Relay Replacement Starter Replacement Control Module References