DTC 12

Column Switch Power Supply And SES Communication Circuit:

Connectors:

CIRCUIT OPERATION
- The column switch (incorporated in ECU) is energized by the battery and the ignition switch (IG1). If one of the harness wires has an open circuit, power will be supplied by the other active harness wire.
- If the column switch (incorporated in ECU) receives a request signal from the ETACS-ECU, the column switch will inform the SWS communication line of various switch conditions.

DTC SET CONDITION
DTC 12 is displayed when the column switch (incorporated in ECU) sends an abnormal signal to the ETACS-ECU.

TROUBLESHOOTING HINTS
- Malfunction of the column switch
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors

DIAGNOSIS
Required Special Tools:
MB991223: Harness Set
MB991502: Scan Tool (MUT-II)

STEP 1. Check the ignition switch position.
If DTC 11 does not set with the ignition switch at "ON" position, go to Step 2.
If DTC 11 sets regardless of the ignition switch positions, go to Step 5.




STEP 2. Check the column switch power supply circuit (battery circuit) at the column switch connector C-86.
1. Disconnect the column switch connector C-86 and measure at the harness side.
2. Voltage between terminal 1 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).
If not approximately 12 volts, go to Step 3. If approximately 12 volts, go to Step 8.




STEP 3. Check the column switch connector C-86 for damage.
If the column switch connector C-86 is damaged, repair or replace it. Refer to Harness Connector Inspection.
Confirm the DTC 12 is not displayed.
If the connector is in good condition, go to Step 4.







STEP 4. Check the harness wires between column switch connector C-86 and battery.

NOTE: After checking intermediate connector C-89 and joint connector C-78, check the wires. If intermediate connector C-89 and joint connector C-78 are damaged, repair or replace them. Refer to Harness Connector Inspection.

If the harness wires between column switch connector C-86 and battery are damaged, repair them.
Confirm the DTC 12 is not displayed.




STEP 5. Check the column switch ground circuit at the column switch connector C-86.
1. Disconnect the column switch connector C-86 and measure at the harness side.
2. Resistance between terminal 4 and ground.
- Should be less than 2 Ohms.
If open circuit, go to Step 6.
If less than 2 Ohms. go to Step 8.




STEP 6. Check the column switch connector C-86 for damage.
If the column switch connector C-86 is damaged, repair or replace it. Refer to Harness Connector Inspection.
Confirm the DTC 12 is not displayed.
If the connector is in good condition, go to Step 7.







STEP 7. Check the harness wires between column switch connector C-86 and ground.

NOTE: After checking junction block connector C-101 and C-109, check the wires. If junction block connector C-101 and C-109 are damaged, repair or replace them. Refer to Harness Connector Inspection.

If the harness wires between column switch connector C-86 and ground are damaged, repair them.
Confirm the DTC 12 is not displayed.







STEP 8. Check the column switch connector C-86 and ETACS-ECU connector C-111 for damage.
If the column switch connector C-86 and ETACS-ECU connector C-111 are damaged, repair or replace them. Refer to Harness Connector Inspection. Confirm the DTC 12 is not displayed.
If the connectors are in good condition, go to Step 9.










STEP 9. Check the harness wires between column switch connector C-86 and ETACS-ECU connector C-111.

NOTE: After checking joint connector C-78, check the wires. If joint connector C-78 is damaged, repair or replace it. Refer to Harness Connector Inspection.

If the harness wires between column switch connector C-86 and ETACS-ECU connector C-111 are damaged, repair them. Confirm the DTC 12 is not displayed.

If the harness wires are in good condition, replace the column switch or ETACS-ECU.
Confirm the DTC 12 is not displayed.