2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 2790

2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 2790

cylinders by turning OFF the fuel injectors. By disabling half of cylinders, the ECM is able to reduce the temperature of the coolant.

Conditions for Running the DTC

The engine is operating.

Conditions for Setting the DTC

All V8

The coolant temperature is warmer than 129掳C (264掳F) for greater than 10 seconds.

6.0L-Hybrid

The coolant temperature is warmer than 132掳C (270掳F) for greater than 10 seconds.

Action Taken When the DTC Sets

* DTC P1258 is a Type A DTC.

* The engine will operate in the Overheated Engine Protection Operating Mode.

* The engine coolant temperature indicator lamp, if equipped, will illuminate.

* The driver information center (DIC), if equipped, may display a message.

* If the protection mode is active and an ECT sensor DTC sets, the protection mode will activate during the next drive cycle until the ECT

sensor DTC runs and passes.

Conditions for Clearing the DTC

DTC P1258 is a Type A DTC.

Reference Information

Description and Operation

* Cooling System Description and Operation (See: Engine, Cooling and Exhaust/Cooling System/Description and Operation/Cooling System

Description and Operation)

* Instrument Cluster Description and Operation (See: Instrument Panel, Gauges and Warning Indicators/Description and

Operation/Instrument Cluster)

* Indicator/Warning Message Description and Operation (See: Instrument Panel, Gauges and Warning Indicators/Description and

Operation/Indicator/Warning Message)

* Audible Warnings Description and Operation (See: Instrument Panel, Gauges and Warning Indicators/Description and Operation/Audible

Warnings)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code

(DTC) Type Definitions)

Scan Tool Reference

Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information

Circuit/System Verification

Note: If DTC P0480, P0481, or P0482 is set, diagnose that DTC first.

1. Observe the engine coolant level. The engine coolant level should be within operating range. Refer to Cooling System Draining and Filling

(Static Fill) (See: Engine, Cooling and Exhaust/Cooling System/Service and Repair/Cooling System Draining and Filling (Static Fill))

2. Ensure that the vehicle has the correct engine coolant, with correct concentration, and is not old, contaminated or contains additives. Refer to

Cooling System Draining and Filling (Static Fill) (See: Engine, Cooling and Exhaust/Cooling System/Service and Repair/Cooling System

Draining and Filling (Static Fill))

3. Inspect the cooling system for the following:

* Leaks

* Kinked or pinched hoses, especially at the radiator

* Loose, missing, or damaged radiator air seals or deflectors

* The radiator and A/C condenser for any air flow obstructions or bent fins-Refer to Symptoms - Engine Cooling (See: Engine, Cooling

and Exhaust/Cooling System/Testing and Inspection/Symptom Related Diagnostic Procedures/Symptoms - Engine Cooling).

Note: A small delay occurs before the ECM changes the cooling fan speed.

4. Command the cooling fans ON in each available speed with a scan tool.