B1001
DTC B1001, B1002: Interior Temperature Sensor SystemInterior Temperature Sensor Circuit:
DTC SET CONDITION
- DTC B1001 is set if there is a short circuit in the interior temperature sensor input circuit.
- DTC B1002 is set if there is a defective connector connection, or if there is an open circuit in the harness.
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
- The A/C-ECU, the interior air temperature sensor, or connector(s) or wiring between the two may be defective.
Past trouble
- If DTC B1001 or B1002 is stored as a past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) between the A/C-ECU and the interior air temperature sensor. If the connectors and wiring are normal, and obviously the ECU is the cause of the trouble, replace the ECU. If in doubt, do not replace the ECU.
TROUBLESHOOTING HINT
- Malfunction of connector.
- Malfunction of the harness.
- Malfunction of the interior temperature sensor.
- Malfunction of the A/C-ECU.
DIAGNOSIS
Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T-III USB Cable
- MB991910: M.U.T-III Main Harness A
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
Use scan tool MB991958 to diagnose the CAN bus lines.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to "ON" position.
3. Diagnose the CAN bus line.
Q: Is the check result satisfactory?
YES : Go to Step 2.
NO : Repair the CAN bus lines. Then go to Step 7.
STEP 2. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
1. Erase the DTC.
2. Turn the ignition switch to "ON" position.
3. Check if the DTC is set.
Q: Is the check result satisfactory?
YES : It can be assumed that this malfunction is intermittent.
NO : Go to Step 3.
STEP 3. Using scan tool MB991958, check data list.
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.
1. Connect scan tool MB991958 to the data link connector.
2. Start the engine.
3. Set scan tool MB991958 to the data reading mode.
- Item 01: Interior temperature sensor.
- Check that the interior temperature matches the displayed value on the scan tool.
NOTE: When this DTC is set and the system is in fail-safe status, the value of service data displays 25° C.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Does the interior temperature match the displayed value on the scan tool?
YES : Replace the A/C-ECU. Then go to Step 7.
NO : Go to Step 4.
STEP 4. Check A/C-ECU connector C-15, C-16 and interior temperature sensor connector C-123 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are A/C-ECU connectors C-15, C-16 and interior temperature sensor connector C-123 in good condition?
YES : Go to Step 5.
NO : Repair or replace the connector. Then go to Step 7.
STEP 5. Check the wiring harness between A/C-ECU connector C-15 (terminals 20), C-16 (terminals 22) and interior temperature sensor connector C-123 (terminals 1 and 2).
NOTE: Also check joint connector C-03 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If joint connector C-03 is damaged, repair or replace the connector.
- Check the sensor signal line and ground line for open and short circuit.
Q: Are the wiring harnesses between A/C-ECU connector C-15 (terminals 20), C-16 (terminals 22) and interior temperature sensor connector C-123 (terminals 1 and 2) in good condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Then go to Step 7.
STEP 6. Check the interior temperature sensor.
1. Disconnect interior temperature sensor connector C-123.
2. When the resistance between the sensor terminals is measured under two or more temperature conditions, the resistance should approximately satisfy the illustrated values.
NOTE: The temperature conditions when checking should not exceed the range shown in the diagram.
Q: Is the interior temperature sensor in good condition?
YES : Replace the A/C-ECU. Then go to Step 7.
NO : Replace the interior temperature sensor. Then go to Step 7.
STEP 7. Recheck for diagnostic trouble code.
Check again if the DTC is set.
1. Connect scan tool MB991958 to the data link connector
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES : The procedure is complete.
NO : Return to Step 1.