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DTC B2101: IG SW start POS.circuit low
DTC B2102: IG SW start POS.circuit high


caution
  • If DTC B2101 or B2102 is set, be sure to diagnose the CAN bus line.
  • Before replacing the ECU, ensure that the communication circuit is normal.




DTC SET CONDITION


WCM sets DTC B2101 or B2012 when the actual state of the ignition switch and the ignition switch position information received from ETACS-ECU via CAN do not match.

TECHNICAL DESCRIPTION (COMMENT)


WCM determines that the abnormality is present, if it has detected discrepancy in the ignition switch level shown below ten consecutive times when WCM has received the CAN message (ignition switch position information) from ETACS-ECU with the ignition switch turned to the ON or START position.
B2101
B2102

TROUBLESHOOTING HINTS



DIAGNOSIS
Required Special Tools:
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)

    • MB991824: Vehicle Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

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 to the data link connector.
(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?

Go to Step 2.

Repair the CAN bus line. (Refer to GROUP 54C, Diagnosis ).

STEP 2. Check ETACS-ECU connector C-317 and WCM connector C-09 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is ETACS-ECU connector C-317 and WCM connector C-09 in good condition?
Go to Step 3.
Repair the defective connector.

STEP 3. Check the wiring harness between WCM connector C-09 (terminal No.9) and ETACS-ECU connector C-317 (terminal No.5).



  • Check the power supply line for open circuit.

Q. Is the wiring harness between WCM connector C-09 (terminal No. 9) and ETACS-ECU connector C-317 (terminal No. 5) in good condition?
Go to Step 4.
The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector.

STEP 4. Using scan tool MB991958, check data list.
Use the ETACS-ECU data list to check the signals related to the ignition voltage.
Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
Item No.
 Item name
 Normal conditions
Item 254
 IG voltage
 Battery positive voltage

Q. Does scan tool MB991958 display the item "IG voltage" as normal condition?
Go to Step 5.
Diagnose the ETACS-ECU. Refer to GROUP 54A, Diagnosis .

STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set to the WCM.
(1)Erase the DTC.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)Check if DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the DTC set?
Replace WCM and register the ID codes. (Refer to .)
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).