ECD SYSTEM (w/o DPF), Diagnostic DTC:P1292, P1293

DTC Code DTC Name
P1292 Short in Engine Coolant Temperature Circuit
P1293 Open in Engine Coolant Temperature Circuit

DESCRIPTION

A thermistor is built into the engine coolant temperature (radiator) sensor, of which the resistance value varies according to the radiator side engine coolant temperature.

The structure of the sensor and its connection to the ECM are the same as those of the Intake Air Temperature (IAT) sensor.

Tech Tips

When either of DTCs P1292 or P1293 are set, the ECM enters fail-safe mode. During fail-safe mode, the radiator side engine coolant temperature is estimated to be 80°C (176°F) by the ECM and the radiator fan motors are operated until the pass condition is detected. Fail-safe mode continues until a pass condition is detected.

DTC No. DTC Detection Conditions Trouble Areas
P1292

Short in engine coolant temperature (radiator) sensor circuit for 0.5 seconds

(1 trip detection logic)

  • Short in engine coolant temperature (radiator) sensor circuit

  • Engine coolant temperature (radiator) sensor

  • ECM
P1293

Open in engine coolant temperature (radiator) sensor circuit for 0.5 seconds

(1 trip detection logic)

  • Open in engine coolant temperature (radiator) sensor circuit

  • Engine coolant temperature (radiator) sensor

  • ECM

Tech Tips

When either of these DTCs are set, check the engine coolant temperature (radiator) by selecting the following menu items on an intelligent tester: Powertrain / Engine / Data List / Engine Coolant Temp (In).

Temperature Displayed Malfunctions
-40°C (-40°F) Open circuit
140°C (284°F) Short circuit

MONITOR DESCRIPTION

The engine coolant temperature (radiator) sensor is used to monitor the radiator side engine coolant temperature. The engine coolant temperature (radiator) sensor has a thermistor with a resistance that varies according to the temperature of the engine coolant. When the coolant temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are reflected in the voltage output from the sensor. The ECM monitors the sensor voltage and uses this value to calculate the radiator side engine coolant temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a fault in the engine coolant temperature (radiator) sensor and sets a DTC.

Example:

If the sensor voltage output is -40°C (-40°F) for 0.5 seconds or more, the ECM determines that there is an open in the engine coolant temperature (radiator) sensor circuit, and sets DTC P1293. Conversely, if the voltage output is 140°C (284°F) for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and sets DTC P1292.

If the malfunction is not repaired successfully, a DTC is set 0.5 seconds after the engine is next started.

WIRING DIAGRAM

A01BH1LE07

INSPECTION PROCEDURE

Tech Tips


  • If other DTCs relating to different systems that have terminal E2 as the ground terminal are output simultaneously, terminal E2 may have an open circuit.

  • Read freeze frame data using an intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (RADIATOR COOLANT TEMPERATURE)


    1. Connect an intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the tester ON.

    3. Select the following menu items: Powertrain / Engine / Data List / Engine Coolant Temp (In).

    4. Read the value.

      Standard
      Between 80°C and 97°C (176°F and 207°F) with warm engine.
      Result
      Temperature Displayed Proceed To
      -40°C (-40°F) A
      140°C (284°F) B
      Between 80°C and 97°C (176°F and 207°F) C

      Tech Tips


      • If there is an open circuit, the intelligent tester indicates -40°C (-40°F).

      • If there is a short circuit, the intelligent tester indicates 140°C (284°F).


    B

    READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN HARNESS) Click here

    C

    CHECK FOR INTERMITTENT PROBLEMS

    A

  2. READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN HARNESS)


    1. Confirm good connection of the connector to the ECM.

    2. A01BEIHE02

      Disconnect the B29 engine coolant temperature (radiator) sensor connector.

    3. Connect terminals 1 and 2 of the engine coolant temperature (radiator) sensor connector on the wire harness side.

    4. Connect an intelligent tester to the DLC3.

    5. Turn the ignition switch to ON and turn the tester ON.

    6. Select the following menu items: Powertrain / Engine / Data List / Engine Coolant Temp (In).

    7. Read the value.

      Standard
      140°C (284°F)

    8. Reconnect the engine coolant temperature (radiator) sensor connector.


    OK

    REPLACE ENGINE COOLANT TEMPERATURE (RADIATOR) SENSOR

    NG

  3. READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN ECM)


    1. Confirm good connection of the connectors to the ECM.

    2. A01BAJPE04

      Disconnect the B29 engine coolant temperature (radiator) sensor connector.

    3. Connect terminals RTHW and E2 of the ECM connector.

      Tech Tips

      Before checking, perform visual and contact pressure checks on the ECM connector.

    4. Connect an intelligent tester to the DLC3.

    5. Turn the ignition switch to ON and turn the tester ON.

    6. Select the following menu items: Powertrain / Engine / Data List / Engine Coolant Temp (In).

    7. Read the value.

      Standard
      140°C (284°F)

    8. Reconnect the engine coolant temperature (radiator) sensor connector.


    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    NG

    REPLACE ECM

  4. READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN HARNESS)


    1. A01BGFRE15

      Disconnect the B29 engine coolant temperature (radiator) sensor connector.

    2. Connect an intelligent tester to the DLC3.

    3. Turn the ignition switch to ON and turn the tester ON.

    4. Select the following menu items: Powertrain / Engine / Data List / Engine Coolant Temp (In).

    5. Read the value.

      Standard
      -40°C (-40°F)

    6. Reconnect the engine coolant temperature (radiator) sensor connector.


    OK

    REPLACE ENGINE COOLANT TEMPERATURE (RADIATOR) SENSOR

    NG

  5. CHECK HARNESS AND CONNECTOR (ENGINE COOLANT TEMPERATURE [RADIATOR] SENSOR - ECM)


    1. A01BEGRE01

      Disconnect the B9 and D1 ECM connectors.

    2. Disconnect the B29 engine coolant temperature (radiator) sensor connector.

    3. Check the resistance.

      Standard resistance (Check for short)
      Tester Connection Specified Condition
      RTHW (B9-20) or B29-2 - E2 (D1-28) or B29-1 10 kΩ or higher
      RTHW (B9-20) or B29-2 - Body ground 10 kΩ or higher

    4. Reconnect the ECM connectors.

    5. Reconnect the engine coolant temperature (radiator) sensor connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM