P1540

DTC P1540: LIN Communication Check by PCM (Sending Message to Radiator Sensor)/DTC P1541: LIN Communication Check by PCM (Receiving Message from Radiator Sensor)






















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).

TECHNICAL DESCRIPTION

- The PCM judges the tampering of the DOR radiator according to the signal from the radiator sensor.

MONITOR EXECUTION

- Continuous

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

- Ignition switch: "ON"
- Battery positive voltage is higher than 10 volts
- Engine coolant temp -30°C(-22°F) to 105°C(221°F)
Judgement Criteria

- The radiator sensor cannot receive the data from the PCM[ When P1540 is set].
- The PCM cannot receive the data from the radiator sensor[ When P1541 is set].
- When the PCM is defective

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)

- Tampering of the DOR radiator
- Malfunction of the PCM
- A poor connection, open circuit, short circuit or damaged circuit is present in the radiator sensor circuit.

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. Measure the battery positive voltage.

(1)Measure the battery positive voltage during cranking.

- The voltage should remain greater than 8 volts while the engine is cranked.

Q. Does the voltage remain greater than 8 volts while the engine is cranked?

YES Go to Step 2.
NO Battery Check.
STEP 2. Check harness connector A-41 at the radiator sensor for damage.





Q. Is the harness connector in good condition?

YES Go to Step 3.

NO Repair or replace it. Harness Connector Inspection.
Then go to Step 9.

STEP 3. Measure the supply voltage at radiator sensor connector A-41.





(1)Disconnect radiator sensor harness connector A-41.
(2)Turn the ignition switch to the "ON" position.
(3)Measure the voltage between harness connector A-41 terminal No.3 and ground.

- The voltage should equal battery positive voltage.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the measured voltage battery positive voltage?

YES Go to Step 6.

NO Go to Step 4.

STEP 4. Check intermediate connector A-13 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q. Are the connectors and terminals in good condition?

YES Go to Step 5.

NO Repair or replace the damaged components. Harness Connector Inspection. Then go to Step 9.

STEP 5. Check for harness damage between radiator sensor connector A-41 (terminal No.3) and MFI relay connector B-17X (terminal No.4).









Q. Is the harness wire in good condition?

YES Then go to Step 6.

NO Repair it. Then go to Step 9.

STEP 6. Check for continuity at radiator sensor harness side connector A-41





(1)Disconnect the connector A-41 and measure at the harness side.
(2)Check for the continuity between terminal No.1 and ground.

- Should be less than 2 ohms.

Q. Does continuity exist?

YES Go to Step 7.

NO Repair it. Then go to Step 9.

STEP 7. Check for harness damage between radiator sensor connector A-41 (terminal No.1) and PCM connector B-19 (terminal No.3).









- Check the communication lines for earth circuit.[ When P1540 is seT] - Check the communication lines for open circuit.[ When P1541 is set]

Q. Is the harness wire in good condition?

YES Go to Step 8.

NO Repair it. Then go to Step 9.

STEP 8. Replace the DOR radiator

Check the diagnostic trouble code (DTC).

Q. Is DTC P1540 or P1541 set?

YES Replace the PCM. Then go to Step 9.
NO The procedure is complete.
STEP 9. Perform the OBD-II drive cycle.

Check the diagnostic trouble code (DTC).

Q. Is DTC P1540 or P1541 set?

YES Repeat the troubleshooting.
NO The procedure is complete.