P1543
Article Updated by TSB-05-13-013DTC P1543: DOR Radiator Tampering Monitor (Temperature Check After Thermostat Open)
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:
Logic Flow Chart
Check Condition
- Battery positive voltage is higher than 11 volts.
- Intake air temp from 0 degree C (32 degrees F) to 40 degrees C (104 degrees F).
- Engine coolant temperature is less than 40 degrees C (104 degrees F).
- The engine coolant temperature - intake air temperature is 5 degrees C (41 degrees F) or less at engine is start.
- When the engine coolant temperature is 77 degrees C (171 degrees 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 Pattern Lists
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 Cooling System, 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 Pattern Lists
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 Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P1543 set?
YES: Repeat the troubleshooting.
NO: The procedure is complete.