P1541

DTC P1540: LIN Communication Check by ECM (Sending Message to Radiator Sensor) [California]
DTC P1541: LIN Communication Check by ECM (Receiving Message from Radiator Sensor) [California]

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).

TECHNICAL DESCRIPTION
- The ECM 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 11 volts
- Engine coolant temp -30 °C (-22 °F) to 110 °C (230 °F)

Judgement Criteria
- The radiator sensor cannot receive the data from the ECM [When P1540 is set].
- The ECM cannot receive the data from the radiator sensor [When P1541 is set].

OBD-II DRIVE CYCLE PATTERN
- None.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CODE TO BE SET ARE:)
- Tampering of the DOR radiator
- Battery failed.
- Connector damage.
- Harness damage.
- 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. 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 : Refer to Chassis Electrical, Battery-Battery check.

STEP 2. Check harness connector A-48 at radiator sensor and harness connector B-11 at ECM for damage.

Q: Is the harness connector in good condition?

YES : Go to Step 3.

NO : Repair or replace it. Refer to General (Electrical), Harness Connector Inspection. Then go to Step 7.

STEP 3. Measure the supply voltage at radiator sensor connector A-48.

1. Disconnect radiator sensor harness connector A-48.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between harness connector A-48 (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 4.

NO : Repair harness wire between MFI relay connector A-33X (terminal No. 2) and radiator sensor connector A-48 (terminal No. 3) because of harness damage. Then go to Step 7.

STEP 4. Check for open circuit or harness damage between radiator sensor connector A-48 and ground.

1. Disconnect the connector A-48 measure at the harness side.




2. Measure the resistance between connector A-48 (terminal No. 1) and ground.
- Should be less than 2 ohms.

Q: Is the measured resistance less than 2 ohms?

YES : Go to Step 5.

NO : Repair it. Then go to Step 7.

STEP 5. Check for short circuit to ground or open circuit between radiator sensor connector A-48 and ECM connector B-11.

1. Disconnect the connector A-48 and B-11 measure at the harness side.




2. Check for the continuity between A-48 (terminal No. 2) connector and ground.
- Not continuity.




3. Measure the resistance between connector A-48 (terminal No. 2) and connector B-11 (terminal No. 99).
- Should be less than 2 ohms.

Q: Is the harness wire in good condition?

YES : Go to Step 6.

NO : Repair it. Then go to Step 7.

STEP 6. 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 P1540 or P1541 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 7.

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 7. Using scan tool MB991958, read the diagnostic trouble code (DTC).

1. Turn the ignition switch to the "ON" position.
2. Read the DTC.
3. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC P1540 or P1541 set?

YES : Repeat the troubleshooting.

NO : The procedure is complete.