P1543

DTC P1543: DOR Radiator Tampering Monitor (Temperature Check After Thermostat Open)

RADIATOR SENSOR CIRCUIT

Radiator Sensor Circuit (Part 1):

Radiator Sensor Circuit (Part 2):

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:

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).
- The engine coolant temperature - intake air temperature is 5 °C (41 °F) or less at engine is start.
- When the engine coolant temperature is 77 °C (171 °F) or higher under the following conditions.
1. Drive the vehicle at the engine speed of 1,700 r/min or more for 10 minutes.
2. The engine load is 30 percent or more.

Judgement Criteria
- When the output temperature of the radiator sensor after the thermostat valve is opened is low

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 18. OBD-II Drive Cycle

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
- Tampering of the DOR radiator
- Engine coolant is insufficient or has deteriorated.
- Malfunction of the thermostat
- 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 engine coolant.
- If the engine coolant is reducing to much, check for coolant leaks and repair if necessary.

Q: Is the check result normal?

YES : Go to Step 2.

NO : Replace or replenish the engine coolant.

STEP 2. Check the thermostat.

- Thermostat inspection. Service and Repair

Q: Is the check result normal?

YES : Go to Step 3.

NO : Repair it. Then go to Step 6.

STEP 3. Water pump check

- Water pump check

Q: Is the check result normal?

YES : Go to Step 4.

NO : Repair it. Then go to Step 6.

STEP 4. 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 5.

NO : Replace the DOR radiator. Then go to Step 6.

STEP 5. Replace the DOR radiator

1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 18. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P1543 set?

YES : Replace the PCM. Then go to Step 6.

NO : The procedure is complete.

STEP 6. 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 18. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P1543 set?

YES : Repeat the troubleshooting.

NO : The procedure is complete.