C1640

DTC C1640: Variant Code un-writing/data Abnormal

CAUTION: If there is any problem in the CAN bus lines, an incorrect diagnostic trouble code may be set. Prior to this diagnosis, diagnose the CAN bus lines. Refer to Diagnostic Trouble code diagnosis.

CAUTION: Whenever the ECU is replaced, ensure that the CAN bus lines are normal.

CIRCUIT OPERATION
The ECM [M/T] or PCM [A/T] communicates with the ABS/TCL-ECU via CAN bus lines, and sends the data from each ECU.

ABS/TCL DTC SET CONDITIONS
The ABS/TCL-ECU always monitors itself while the system is working. If the ECU detects any faults, it will set this diagnosis code.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THESE DTCs ARE TO SET ARE:)
A different hydraulic unit is used. (integrated with ABS/TCL-ECU)

DIAGNOSIS

Required Special Tools:
^ 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.

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) 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, refer to Diagnosis. Then go to Step 2.

STEP 2. Recheck for diagnostic trouble code.





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) Turn the ignition switch to the "ON" position.
(2) Erase the DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
(4) Turn the ignition switch to the "ON" position.
(5) Check if the DTC is set.
(6) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC C1640 set?
YES: Replace the hydraulic unit (integrated with ABS/TCL-ECU).
NO: The procedure is complete.