Inspection Procedure O-9

Driver Seat Belt Switch Input Circuit:

CIRCUIT OPERATION
The ETACS-ECU operates various functions according to the input signals from the driver's seat belt switch.

TECHNICAL DESCRIPTION (COMMENT)
The driver's seat belt switch input signal is used to operate the following functions. If the input signal is an error, these functions will not work normally.
- Seat belt tone alarm function
- Seat belt warning light

TROUBLESHOOTING HINTS
- Malfunction of the driver's inner seat belt (driver's seat belt switch)
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors

DIAGNOSIS
Required Special Tools:
MB991223: Test Harness Set
MB991502: Scan Tool (MUT-II)
MB991529: Diagnostic Trouble Code Check Harness







STEP 1. Check the driver's seat belt switch.
If the driver's seat belt switch is damaged, replace the driver's inner seat belt.
The driver's seat belt switch input signal should be able to be checked and the functions, which are described in the "Technical Description (comment)," should work normally.
If the driver's seat belt switch is in good condition, go to Step 2.




STEP 2. Check the driver's seat belt switch ground circuit at driver's seat belt switch connector D-13.
1. Disconnect driver's seat belt switch connector D-13 and measure at the harness side.
2. Resistance between terminal 2 and ground.
- Should be less than 2 Ohms.
If open circuit, go to Step 3.
If less than 2 Ohms. go to Step 5.




STEP 3. Check driver's seat belt switch connector D-13 for damage.
If the driver's seat belt switch connector D-13 is damaged, repair or replace it. Refer to Harness Connector Inspection.
The driver's seat belt switch input signal should be able to be checked and the functions, which are described in the "Technical Description (comment)," should work normally.
If the connector is in good condition, go to Step 4.




STEP 4. Check the harness wire between driver's seat belt switch connector D-13 and ground.
If the harness wire between driver's seat belt switch connector D-13 and ground is damaged, repair it.
The driver's seat belt switch input signal should be able to be checked and the functions, which are described in the "Technical Description (comment)," should work normally.







STEP 5. Check the driver's seat belt switch connector D-13 and ETACS-ECU connector C-111 for damage.
If the driver's seat belt switch connector D-13 and ETACS-ECU connector C-111 are damaged, repair or replace them. Refer to Harness Connector Inspection.
The driver's seat belt switch input signal should be able to be checked and the functions, which are described in the "Technical Description (comment)," should work normally.
If the connectors are in good condition, go to Step 6.










STEP 6. Check the harness wires between driver's seat belt switch connector D-13 and ETACS-ECU connector C-111.

NOTE: After checking intermediate connector C-90, check the wires. If intermediate connector C-90 is damaged, repair or replace it. Refer to Harness Connector Inspection.

If the harness wires between driver's seat belt switch connector D-13 and ETACS-ECU connector C-111 are damaged, repair them.
The driver's seat belt switch input signal should be able to be checked and the functions, which are described in the "Technical Description (comment)," should work normally.
If the harness wires are in good condition, replace the ETACS-ECU.
The driver's seat belt switch input signal should be able to be checked and the functions, which are described in the "Technical Description (comment)," should work normally.