DTC P118A, P11C9, P1387, P26C0, P26C2, U111A, or U1379

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5511918 DTC P118A, P11C9, P1387, P26C0, P26C2, U111A, or U1379 Diagnostic Instructions 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 DTC Descriptor DTC P118A Engine Block Coolant Control Valve Position Sensor Circuit Low DTC P11C9 Engine Block Coolant Control Valve Position Sensor Circuit High DTC P1387 Engine Block Coolant Control Valve Position Sensor Stop Performance DTC P26C0 Engine Block Coolant Control Valve Stuck Open DTC P26C2 Engine Block Coolant Control Valve Stuck Closed DTC U111A Lost Communication with Engine Block Coolant Control Valve DTC U1379 Invalid Data Received from Block Coolant Valve Actuator Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performanc
Ignition	U111A*	U111A*	—	—
Serial Data	U0672, U111A, U111E, U1348	U0672, U111A, U111E, U1348	U0672, U111A, U111E, U1348	U1379*
Ground	—	U111A	—	—
* Additional DTCs may set

Internal — Component

	Component	DTC	Condition
	Engine Coolant Control Valve Position Sensor @ Q97B Engine Coolant Flow Control Valve - Block	P118A P11C9	This DTC sets when there is an internal component issue: Open/High Resistance
	© 2023 Gene	ral Motors. Al	Short to Ground l rights reserved.

Component	DTC	Condition
		Short to Voltage
Engine Block Coolant Valve @ Q97B Engine Coolant Flow Control Valve - Block	P26C0 P26C2	This DTC sets when there is an internal component issue: Control Valve = Stuck — Closed Control Valve = Stuck — Open

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

Circuit	Description
Ignition	Supplied from a fuse.
Serial Data	Digitally encoded information for communication between devices.
Ground	Chassis Ground

Component	Description
K20 Engine Control Module	The control module contains a microprocessor used to process input data to control outputs. The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.
Q97B Engine Coolant Flow Control Valve - Block	The valve is actuated by a DC motor. Q97B is part of the component: Q97 Engine Coolant Flow Control Valve

Conditions for Running the DTC P118A, P11C9, P1387 DTC P117A, U111A = Not set DTCs related to the following system/component = Not Set – KR75 Engine Controls Ignition Relay { P118A } Engine Block Coolant Control Valve Position = Less than −7° { P11C9 } Engine Block Coolant Control Valve Position = Greater than 117° Ignition Voltage = Greater than 11 V Frequency the DTC runs = Continuously — After the running conditions are met P26C0, P26C2 DTC P117A, U111A = Not set DTCs related to the following system/component = Not Set – KR75 Engine Controls Ignition Relay { P26C0 } DTC P118A = Not set Engine Block Coolant Control Valve Position = −5 to 115° Ignition Voltage = Greater than 11 V Frequency the DTC runs = Continuously — After the running conditions are met U111A, U1379 Ignition = On Ignition Voltage = Greater than 11 V Power Mode = Run Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC P118A, P11C9, P1387, P26C0, P26C2 Engine Block Coolant Control Valve Position = Not within a calibrated range U111A Serial data message from component: Q97B Engine Coolant Flow Control Valve - Block = Not Received — For greater than 1.0 s U1379 Serial data message from component: Q97B Engine Coolant Flow Control Valve - Block = Not within a calibrated range Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type A DTC Reference Information Schematic Reference Engine Heating/Cooling Schematics Connector End View Reference Master Electrical Component List 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 Circuit/System Verification

1. Ignition » On / Vehicle » In Service Mode

Note

This step only applies to the following component DTCs: Q97B Engine Coolant Flow Control Valve - Block

2. Verify DTC P118A, P11C9, P1387, P26C0, P26C2, U111A, U1348, U1379 is not set. ⇒ If DTC P118A, P11C9, P1387, P26C0, P26C2 is set and no other DTCs are set Replace the component: Q97B Engine Coolant Flow Control Valve - Block ⇒ If DTC U111A, U1379 and one or more of the DTCs P118A, P11C9, P1387, P26C0, P26C2 is set Refer to: Circuit/System Testing ⇒ If DTC U111A, U1348, U1379 is set and other DTCs are set Refer to: DTC U1345-U1349 ⇓ If none of the DTCs are set
3. Verify the scan tool parameter: Engine Block Coolant Control Valve Position = The value should not spike or drop out. Perform the action while monitoring the parameter: Wiggle the harness and connector: Q97B Engine Coolant Flow Control Valve - Block Wiggle the harness and connector: K20 Engine Control Module ⇒ If the value spikes or drops out Repair as necessary » Wiring / Terminal(s) / Electrical Connector(s) ⇓ If the value does not spike or drop out
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Verify the DTC does not set. ⇒ If the DTC sets Refer to: Circuit/System Testing ⇓ If the DTC is not set
5. All OK. Circuit/System Testing

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.

1. Ignition/Vehicle & All vehicle systems » Off
2. Disconnect the electrical connector: Q97B Engine Coolant Flow Control Valve - Block
3. Test for less than 10 Ω between the test points: Ground terminal 2 & Ground ⇒ If greater than 10 Ω 3.1. Disconnect the ground connection: G117 3.2. Test for less than 2 Ω between the test points: Ground terminal 2 @ Component harness & G117 ⇒ 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
4. Ignition » On / Vehicle » In Service Mode
5. Verify a test lamp turns On between the test points: Ignition circuit terminal 3 & Ground ⇒ If the test lamp does not turn On and the circuit fuse is OK 5.1. Ignition/Vehicle » Off & Remove » Test lamp 5.2. Test for less than 2 Ω between the test points: Ignition circuit terminal 3 & Output terminal @ F88UA 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 5.1. Ignition/Vehicle » Off & Remove » Test lamp 5.2. Test for infinite resistance between the test points: Ignition circuit terminal 3 & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇒ If infinite resistance » Replace the component: Q97B Engine Coolant Flow Control Valve - Block ⇓ If the test lamp turns On
6. Test for 8 to 10 V between the test points: Serial Data circuit terminal 1 @ Component harness & Ground ⇓ If less than 8 V 6.1. Ignition/Vehicle » Off 6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 6.3. Test for infinite resistance between the test points: Serial Data circuit terminal 1 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 6.4. Test for less than 2 Ω between the test points: Serial Data circuit terminal 1 @ Component harness & 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 greater than 10 V 6.1. Ignition/Vehicle » Off 6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 6.3. Ignition » On / Vehicle » In Service Mode 6.4. Test for less than 1 V between the test points: Serial Data circuit terminal 1 @ Component harness & 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 between 8 and 10 V
7. Test or replace the component: Q97B Engine Coolant Flow Control Valve - Block Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Engine Coolant Flow Control Valve Replacement — Q97B Engine Coolant Flow Control Valve - Block For control module replacement, programming, and setup refer to: Control Module References Additional Procedures Engine Block Coolant Control Valve Position Learn — Perform only when the following component/system is replaced or serviced: Q97B Engine Coolant Flow Control Valve - Block — Replaced Engine Coolant Control Valve Learn — Perform only when the following component/system is replaced or serviced: Q97B Engine Coolant Flow Control Valve - Block — Replaced Engine Coolant Flow Control Valve Learn — Perform only when the following component/system is replaced or serviced: Q97B Engine Coolant Flow Control Valve - Block — Replaced