DTC 13

Front-ECU Power Supply And SWS Communication Circuit:

Connectors:

CIRCUIT OPERATION
- The front-ECU is energized by the battery and the ignition switch (IG2). If one of the harness wires has an open circuit, power will be supplied by the other active harness wire.
- The front-ECU communicates with other ECUs and performs control functions through the SWS communication line.

DTC SET CONDITION
This DTC is displayed when the front-ECU sends an abnormal signal to the ETACS-ECU.

TROUBLESHOOTING HINTS
- Malfunction of the front-ECU
- 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 pos
If DTC 13 does not set with the ignition switch at "ON" position, go to Step 2.
If DTC 13 sets regardless of the ignition switch positions, go to Step 5.




STEP 2. Check the front-ECU power supply circuit (battery circuit) at the front-ECU connector A-09X.
1. Disconnect the front-ECU connector A-09X and measure at the relay box side.
2. Voltage between terminal 16 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).
If not approximately 12 volts, go to Step 3.
If approximately 12 volts, replace the front-ECU.
Confirm the DTC 13 is not displayed.




STEP 3. Check the front-ECU connector A-09X for damage.
If the front-ECU connector A-09X is damaged, repair or replace it. Refer to Harness Connector Inspection. Confirm the DTC 13 is not displayed.
If connector is in good condition, go to Step 4.




STEP 4. Check the harness wire between front-ECU connector A-09X and battery.
If the harness wires between front-ECU connector A-09X and battery is damaged, repair it.
Confirm the DTC 13 is not displayed.




STEP 5. Check the front-ECU ground circuit at the front-ECU connector A-09X.
1. Disconnect the front-ECU connector A-09X and measure at the relay box side.
2. Resistance between terminal 1 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 front-ECU connector A-09X for damage.
If the front-ECU connector A-09X is damaged, repair or replace it. Refer to Harness Connector Inspection. Confirm the DTC 13 is not displayed.
If connector is in good condition, go to Step 7.




STEP 7. Check the harness wires between front-ECU connector A-09X and ground.
If the harness wire between front-ECU connector A-09X and ground is damaged, repair it.
Confirm the DTC 13 is not displayed.







STEP 8. Check the front-ECU connector A-09X and ETACS-ECU connector C-111 for damage.
If the front-ECU connector A-09X and ETACS-ECU connector C-111 are damaged, repair or replace them. Refer to Harness Connector Inspection.
Confirm the DTC 13 is not displayed.
If the connectors are in good condition, go to Step 9.










STEP 9. Check the harness wires between front-ECU connector A-09X and ETACS-ECU connector C-111.

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

If the harness wires between front-ECU connector A-09X and ETACS-ECU connector C-111 are damaged, repair them. Confirm the DTC 13 is not displayed.
If the harness wires are in good condition, replace the front-ECU or ETACS-ECU.
Confirm the DTC 13 is not displayed.