P1544

DTC P1544: DOR Radiator Tampering Monitor (Temperature Check Before Thermostat Open)

Radiator Sensor Circuit Part 1:

Radiator Sensor Circuit Part 2:

RADIATOR SENSOR CIRCUIT

CIRCUIT OPERATION
- The battery voltage is applied from the ignition switch to the radiator sensor (terminal No.3), and it is grounded to the vehicle body from the radiator sensor (terminal No.1).
- The radiator sensor (terminal No.2) sends the sensor signal to the powertrain control module (terminal No.3).

MONITOR EXECUTION
- Once per driving cycle

MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Not applicable

Sensor (The sensor below is determined to be normal)
- Not applicable

DTC SET CONDITIONS

Logic Flow Chart:

Logic Flow Chart

Check Condition
- Battery positive voltage is higher than 11 volts.
- Intake air temp from 0 °C (32 °F) to 40 °C (104 °F).
- Engine coolant temperature is less than 40 °C (104 °F) when at engine start.
- The engine coolant temperature - intake air temperature is 5 °C (41 °F) or less at engine start.
- Vehicle speed is lower than 1.5km/h (1mph).

Judgement Criteria
- When the output temperature of the radiator sensor before the thermostat valve is opened is high, the sensor is defective.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19. OBD-II Drive Cycle

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
- Tampering of the DOR radiator
- Malfunction of the thermostat
- Engine coolant is insufficient or has deteriorated.
- Malfunction of the water pump
- Malfunction of the PCM

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A

STEP 1. Check the thermostat.

Thermostat inspection (Refer to Thermostat inspection).

Q: Is the check result normal?

YES: Go to Step 2.

NO: Repair it. Then go to Step 4.

STEP 2. DOR radiator sensor installation check

Check that the sensor is installed securely and operates normally.

Q: Is the check result normal?

YES: Go to Step 3.

NO: Replace the DOR radiator. Then go to Step 4.

STEP 3. Replace the DOR radiator
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P1544 set?

YES: Replace the PCM. Then go to Step 4.

NO: The procedure is complete.

STEP 4. Perform the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19. OBD-II Drive Cycle

2. Check the diagnostic trouble code (DTC).

Q: Is DTC P1544 set?

YES: Repeat the troubleshooting.

NO: The procedure is complete.