P1543
DTC P1543: DOR Tampering Monitor (Temperature Check After Thermostat Open) [California]RADIATOR SENSOR CIRCUIT
Radiator Sensor Circuit (Part 1):
Radiator Sensor Circuit (Part 2):
CIRCUIT OPERATION
- The battery voltage is applied from the MFI relay 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 ECM (terminal No. 99).
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 temperature is between 0 °C (32 °F) to 40 °C (104 °F) when the engine is started.
- Engine coolant temperature is between 0 °C (32 °F) to 40 °C (104 °F) when the engine is started.
- The engine coolant temperature-intake air temperature is 5 °C (41 °F) or less when the engine is started.
- 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 1,438 r/min or more for 10 minutes.
2. The engine load is 31 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 MFI 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.
- Thermostat failed.
- Water pump failed.
- ECM failed.
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 Engine Cooling, 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. Replace the DOR radiator.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
2. Connect scan tool MB991958 to the data link connector.
3. Turn the ignition switch to the "ON" position.
4. Read the DTC.
5. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC P1543 set?
YES : Replace the ECM. When the ECM is replaced, register the ID code. Refer to ID Code Registration Judgment Table [Vehicles with KOS] or ID Code Registration Judgment Table [Vehicles with WCM]. Then go to Step 6.
NO : It can be assumed that this malfunction is intermittent. Refer to General (Body and Chassis), How to Use Troubleshooting/Inspection Service Points-How to Cope with Intermittent Malfunctions.
STEP 6. Perform the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to MFI 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.