B1034

Code No.B1034: Ambient temperature sensor system (short circuit)
Code No.B1035: Ambient temperature sensor system (open circuit)














DTC SET CONDITION

- DTC B1034 is set if there is a short circuit in the ambient air temperature sensor input circuit.
- DTC B1035 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 ambient air temperature sensor, or connector(s) or wiring between the two may be defective.

Past trouble

- If DTC B1034 or B1035 is stored as a past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) between the A/C-ECU and the ambient 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 ambient air temperature sensor.
- Malfunction of the A/C-ECU.

DIAGNOSIS

STEP 1. Using scan tool MB991958, diagnose the CAN bus line

(1)
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.

Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."

(2)Turn the ignition switch to the "ON" position.

(3)Diagnose the CAN bus line.

(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the CAN bus line found to be normal?

YES Go to Step 2.
NO Repair the CAN bus line. CAN Bus Diagnostics Chart).
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 DTC set?

YES Go to Step 3.
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
STEP 3. Check ambient air temperature sensor connector A-48 and ETACS-ECU connector C-410 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Are ambient air temperature sensor connector A-48 and ETACS-ECU connector C-410 in good condition?

YES Go to Step 4.
NO Repair or replace the connector. Harness Connector Inspection.
STEP 4. Check the wiring harness between ambient air temperature sensor connector A-48 (terminals 2 and 1) and ETACS-ECU connector C-410 (terminals 7 and 14).

- Check the sensor signal line and ground line for open or short circuit.

Q. Is the wiring harness between ambient air temperature sensor connector A-48 (terminals 2 and 1) and ETACS-ECU connector C-410 (terminals 7 and 14) in good condition?

YES Go to Step 5.
NO Repair the wiring harness.
STEP 5. Check the ambient air temperature sensor.





Measure the resistance between connector terminals 1 and 2 under at least two different temperatures. The resistance values should generally match those in the graph.
NOTE:
The temperature at the check should not exceed the range in the graph.

Q. Is the ambient air temperature sensor in good condition?

YES Replace the A/C-ECU. Then go to Step 6.

NO Replace the ambient air temperature sensor. Then go to Step 6.

STEP 6. 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 DTC set?

YES Return to Step 1.
NO The procedure is complete.