DTC 21
Short Circuit Communication LineSWS Communication Circuit:
Connectors:
DTC 21 SHORT CIRCUIT IN COMMUNICATION LINE
ETACS-ECU, column switch (incorporated in ECU) and front-ECU communicate with each other through the SWS communication line.
DTC SET CONDITION
This DTC is displayed when the SWS communication line remains at low level for 0.3 seconds. No other DTC is displayed if DTC 21 is displayed.
TROUBLESHOOTING HINTS
- Malfunction of the ETACS-ECU
- Malfunction of the column switch
- Malfunction of the front-ECU
- Damaged harness wires or connectors
DIAGNOSIS
Required Special Tools:
- MB991223: Harness Set
- MB991502: Scan Tool (MUT-II)
STEP 1. Check the ETACS-ECU connector C-82, column switch connector C-60 and front-ECU connector A-09X for damage.
Q: Are ETACS-ECU connector C-82, column switch connector C-80 and front-ECU connector A-09X in good condition?
YES: Go to Step 2.
NO: Repair or replace them. Refer to Harness Connector Inspection. Confirm the DTC 21 is not displayed.
STEP 2. Check the harness wires from ETACS-ECU connector C-82 to column switch connector C-60 and front-ECU connector A-09X.
NOTE: After inspecting intermediate connectors C-66, check the wires. If intermediate connectors C-66 is damaged, repair or replace them. Refer to Harness Connector Inspection.
Q: Are the harness wires from ETACS-ECU connector C-82 to column switch connector C-60 and front-ECU connector A-09X In good condition?
YES: Go to Step 3.
NO: Replace them. Confirm the DTC 21 is not displayed.
STEP 3. Check the column switch.
Disconnect column switch connector C-60.
Q: Does DTC 21 set?
YES: Go to Step 4.
NO (DTC 12 sets): Replace the column switch. Confirm the DTCs 12 and 21 are not displayed.
STEP 4. Check the front-ECU.
Disconnect front-ECU connector A-09X.
Q: Does DTC 21 set?
YES: Replace the ETACS-ECU. Confirm the DTC 21 is not displayed..
NO (DTC 13 sets): Replace the front-ECU. Confirm the DTCs 13 and 21 are not displayed.