DTC P3051, P3053, or P3055

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. DTC Descriptors DTC P0351 DC/DC Converter Output Voltage Sensor Circuit Low DTC P3053 DC/DC Converter Output Voltage Sensor Circuit High DTC P3055 DC/DC Converter Output Voltage Performance For symptom byte information, refer to Symptom Byte List Diagnostic Fault Information

Circuit Number	Circuit Function	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performan
6340	B+	P3051, P3055	P3051, P3055	—	—
2172	Control	P3051, P3055	1	P3053. P3055	P3055
250	Ground	—	P3051, P3055	—	—
1. Components and control modules powered by circuit 2172 are inoperative. Data communication DTCs may be set.

Circuit/System Description The T19 Multifunction Power Supply Converter is supplied voltage through B+ circuit 8040 and B+ circuit 6340. Ground is provided by ground circuit 250, of which there are two redundant circuits. The T19 Multifunction Power Supply Converter is used to maintain constant battery voltage to necessary components during an auto engine stop/start event. At the T19 Multifunction Power Supply Converter, the B+ circuit 8040 provides voltage to control circuit 2172. The K20 Engine Control Module commands the KR27 Starter Relay by providing voltage on the control circuit 625. The T19 Multifunction Power Supply Converter monitors control circuit 625 as an indicator that the K20 Engine Control Module has commanded the engine to start, ending the auto engine stop/start event. During the engine start, the T19 Multifunction Power Supply Converter will supply voltage on control circuit 2172, which provides critical components and control module a stable voltage during the engine start event. The T19 Multifunction Power Supply Converter communicates voltage on control circuit 2172 to the K20 Engine Control Module on the powertrain CAN bus. The K20 Engine Control Module compares voltage on ignition circuit 439 voltage to the indicated voltage received from the T19 Multifunction Power Supply Converter to determine if there is a system fault. C diti f R i th DTC Conditions for Running the DTC Ignition ON Conditions for Setting the DTC P3051 The K20 Engine Control Module detects less than 1 V on the T19 Multifunction Power Supply Converter control circuit 2172. P3053 The K20 Engine Control Module detects greater than 18 V on the T19 Multifunction Power Supply Converter control circuit 2172. P3055 The K20 Engine Control Module detects a difference of more than 1 v between the K20 Engine Control Module ignition circuit 439 and the T19 Multifunction Power Supply Converter control circuit 2172 or a difference of greater than 2 V between the K20 Engine Control Module ignition circuit 439 and the T19 Multifunction Power Supply Converter Voltage Output 1 Circuit 2172 when compared to the pre cranking voltage snapshot during the restart during an Autostart/Autostop. Action Taken When the DTC Sets The DTCs are type B DTC. Conditions for Clearing the DTC The DTC’ are type B DTC. Diagnostic Aids Any data communication DTCs or related concerns must be corrected before diagnosing DTC P3051, P3053, or P3055. Only Replace a Component if the DTC resets during the current drive cycle. The T19 Multifunction Power Supply Converter is not capable of setting DTCs. The K20  Engine Control Module sets DTCs on behalf of the T19 Multifunction Power Supply Converter. The K20 Engine Control Module and T19 Multifunction Power Supply Converter communicate on the powertrain CAN bus. If the K20 Engine Control Module loses communication with the T19 Multifunction Power Supply Converter for any reason, the K20 Engine Control Module will not be able to monitor the voltages of the T19 Multifunction Power Supply Converter. The K20 Engine Control Module interprets this as a loss of voltage and DTC P3051 and/or P3055 may set as a result. If any of the DTCs P3051 thorough P3056 are set inspect the T19 Multifunction Power Supply Converter connector for evidence of Corrosion or loose terminals and replace as necessary, if no terminal issues are found. apply a light coat of Dielectric grease to the terminals, clear DTC’s and revaluate after performing 5 stop start events. If both DTC P3055 & DTC P3056 are set, the condition may be caused by an internally shorted starter, starter wiring circuits 6 and 4358 may be shorted together. If DTC P3055 is set, but DTC P3056 is not set the condition may be caused by an over- current event on the T19 Multifunction Power Supply Converter Regulated Voltage Output 1 Circuit 2172, that can cause the module to stop regulating voltage. If DTC P3055 is set, verify the ground connection for ground circuit 6151 and ground circuit  250 are clean, tight, and in the correct location. Verify all components and control module powered by the T19 Multifunction Power Supply Converter circuit 2172 are operating properly. The T19 Multifunction Power Supply Converter B+ circuit 8040 terminal 11 supplies voltage to the T19 Multifunction Power Supply Converter control circuit 2172 Terminal 10. The last 2 digits of the circuit number are significant in identifying its power and ground functions. – Circuits ending in 42 are primary fused B+ circuits (generally the first fuse in the circuit after the battery) – Circuits ending in 40 are secondary fused circuits (generally fuses in a fuse block after the primary circuit) – Circuits ending in 39 and 41 are ignition voltage circuits. – Circuits ending in 50 are grounds. – Circuits ending in 51 are low reference (ground) circuits. Reference Information Schematic Reference Starting and Charging Schematics Connector End View Reference Master Electrical Component List Description and Operation Stop/Start 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. Ignition Off and all vehicle systems OFF.

Note

The battery voltage should stabilize after a few minutes of turning the ignition/vehicle Off.

2. Verify the battery voltage is within 12.4 V to 12.8 V at the C1 Battery. ⇒ If not within the specified range Refer to Battery Inspection/Test ⇓ If within the specified range
3. Engine Running with all accessories off, allow the system voltage to stabilize.
4. Headlamps On.
5. Test for 13 V to 15 V at the C1 Battery. ⇒ If not within the specified range Refer to Charging System Test ⇓ If within the specified range
6. Verify no data communication DTCs are set. ⇒ If data communication DTCs are set Diagnose these DTCs first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If no data communication DTCs are set
7. Verify any of the DTC’s P0615, P0616, or P0617 are not set ⇒ If any of the DTC’s are set Refer To: DTC P0615, P0616, or P0617 ⇓ If any of the DTC’s are not set
8. Verify DTC P3051, P3053, or P3055 is not set as current. ⇒ If none of the DTCs are not set Current 8.1. Clear all DTCs. 8.2. Road test the vehicle and perform a minimum of 2 Autostart/Autostop events. 8.3. Verify any of the DTC’s P3051, P3053, or P3055 have not reset. ⇒ If any of the DTC have reset Proceed to Step 9. ⇓ If any of the DTC’s P3051, P3053, or P3055 have not reset 8.4. The condition may be an intermittent fault and is currently not present.
9. Ignition On vehicle in service mode.
10. Perform the scan tool control function: Command the Starter Pinion Solenoid On.
11. Verify the engine is not cranking. ⇒ If the engine is cranking Refer to: Circuit/System Testing — Starter System Test ⇓ If the engine is not cranking
12. Refer to: Circuit/System Testing — T19 Multifunction Power Supply Converter Input/Output Circuit Test Circuit/System Testing — Starter System Test
13. Ignition On vehicle in service mode.
14. Remove the Kr27 Starter Relay.
15. Perform the scan tool control function: Command the Starter Pinion Solenoid On.
16. Verify a test lamp does not turn On between the test points: M64 Starter Motor Terminal 1 X1 & Ground. ⇒ If the test lamp turns On Repair the short to voltage on the circuit 6 ⇓ If the test lamp does not turn On
17. Replace the M64 Starter Motor. Circuit/System Testing — T19 Multifunction Power Supply Converter Input/Output Circuit Test

Note

Circuit/System Verification must be performed before proceeding with Circuit/System Testing.

Note

Do not replace the T19 Power Supply control module if you cannot reproduce the codes during a drive cycle.

1. Ignition Off, disconnect the connector at the T19 Multifunction Power Supply Converter.
2. Verify a test lamp illuminates between ground circuit terminal 7 and B+. ⇒ If the test lamp does not illuminate Repair the open/high resistance on circuit 250 or the ground connection. ⇓ If the test lamp illuminates
3. Verify a test lamp illuminates between ground circuit terminal 12 and B+. ⇒ If the test lamp does not illuminate Repair the open/high resistance on circuit 250 or the ground connection. ⇓ If the test lamp illuminates
4. Verify a test lamp illuminates between B+ circuit terminal 11 and ground. ⇒ If the test lamp does not illuminate and the circuit fuse is good 4.1. Test circuit 8040 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 4.2. Verify the fuse is not open and there is voltage at the fuse. ⇒ If the test lamp does not illuminate and the circuit fuse is open 4.1. Test circuit 8040 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 2172 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 4.3. Replace the T19 Multifunction Power Supply Converter. ⇓ If the test lamp illuminates
5. Ignition On vehicle in Service mode.
6. Verify a test lamp does not turn on between control circuit terminal 10 and ground. ⇒ If the test lamp turns on Repair the short to voltage on circuit 2172. ⇓ if the test lamp does not turn on
7. Remove all appropriate fuses supplied by circuit 2172.
8. Test for infinite resistance between Terminal 10 at the T19 Multifunction Power Supply Converter and ground. ⇒ If less than infinite resistance Repair the short to ground on circuit 2172. ⇓ If infinite resistance
9. Connect all connectors.
10. Clear all DTCs.
11. Road test the vehicle allowing a minimum of 5 engine auto stop/start events to occur.
12. Verify DTC P3051, P3053, or P3055 did not reset. ⇒ If any of the DTCs reset 12.1. Verify the Ignition circuit 439 at the K20 Engine Control Module is within 1 V of control circuit 2172 at the T19 Multifunction Power Supply Converter. ⇒ if not within the specified value Repair the open/high resistance in circuit 439. ⇓ If within the specified value 12.2. Replace the T19 Multifunction Power Supply Converter. ⇓ If any of the DTCs did not reset
13. A fault is not currently present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. Multifunction Power Supply Converter Replacement