P1543

DTC P1543: DOR Radiator Tampering Monitor (Temperature Check After 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).
- 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 (Refer to Thermostat inspection).

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.