P1115

DTC P1115 COOLANT TEMPERATURE SENSOR CIRCUIT FOR COOLANT HEAT STORAGE SYSTEM

HINT: Although each DTC title says "Coolant Temperature Sensor", these DTCs are related to the coolant heat storage tank outlet temperature sensor.

CIRCUIT DESCRIPTION

DTC Detection Condition:

This system uses an electric pump to supply hot coolant stored in the coolant heat storage tank into the cylinder head of the engine, in order to optimize engine starting combustion and reduce the amount of unburned gas that is discharged while the engine is started. Before the engine starts, the ECM operates the electric water pump to direct the hot coolant in the heat storage tank into the engine, in order to heat the cylinder head (this process is called "preheat mode" ). The duration of the operation of the electric water pump is variable, depending on the temperature of the cylinder head. During the normal operation of the engine, the water valve opens the passage between the cylinder head and the heater and closes the passage between the cylinder head and the tank. During preheat mode in which the cylinder head is heated, the water valve opens the passage between the tank and the cylinder head, in order to allow the coolant to flow from the tank to the cylinder head. At this time, in order to warm up the intake port quickly before the engine is started, the coolant flows in the reverse direction.

The sensor for the system, which is provided at the tank outlet, is constructed similarly to the engine coolant temperature sensor and is connected to the ECM. The CHS tank outlet temperature sensor has a built in thermistor, whose resistance varies with the coolant temperature.

HINT: If the ECM detects the DTC P0115, P0117 or P0118, it operates the fail-safe function in which the engine coolant temperature is assumed to be 80 °C (176 °F).

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

Component Operating Range:

The ECM monitors the sensor voltage and uses this value to control the coolant heat storage (CHS) system properly. If the sensor output voltage deviates from the normal operating range, the ECM determines that the CHS tank outlet temperature sensor circuit has malfunctioned, and outputs a DTC.

Example:
A sensor output voltage of -40 °C (-40 °F) or 140 °C (284 °F) is determined to be malfunction.

Wiring Diagram:

Step 1 - 2:

Step 3:

INSPECTION PROCEDURE

CAUTION: Be careful when replacing any part in the system or changing the coolant because the coolant in the heat storage tank is hot even if the engine is cold.

HINT:
- If different DTCs related to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.
- To check the coolant heat storage (CHS) system, the ECM may cause the water pump of the CHS system to operate 5 hours after the power switch has been turned OFF.
- Read freeze frame data using the intelligent tester II. Freeze frame data records the engine condition when malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

CHECK FOR INTERMITTENT PROBLEMS

HINT: Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect when the ECM is in test mode with a hand-held tester. In check mode, the ECM uses 1 trip detection logic, which has a higher sensitivity to malfunctions than normal mode (default) using 2 trip detection logic.

a. Clear the DTCs.
b. Switch the hand-held tester from normal mode to check mode.
c. Perform a simulation test.
d. Check the connector(s) and terminal(s).
e. Wiggle the harness(s) and connector(s).