Inspection Procedure L-4

The ETACS-ECU does not Receive Any Signal from the Driver's or the Front Passenger's Door Switch

Front Door Switches Input Circuit:

Connectors:

CIRCUIT OPERATION
The ETACS-ECU operates the following functions or systems according to signal from the driver's or front passenger's door switches:
- Ignition key reminder tone alarm function
- Light reminder tone alarm function
- Power window timer function
- Headlight automatic shutdown function
- Dome light

TECHNICAL DESCRIPTION (COMMENT)
If the signal is not normal, the functions or systems, which are described in "CIRCUIT OPERATION", do not work normally. If the signal is not normal, the driver's or front passenger's door switch or the ETACS-ECU may be defective.

TROUBLESHOOTING HINTS
- Malfunction of the driver's or front passenger's door switches
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors

DIAGNOSIS

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





STEP 1. Check the input signal (by using the Pulse check).
Check the input signals from the front door switches.

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. When each front door is opened and closed, check if scan tool MB991502 sounds or not.

Q: Does scan tool MB991502 sound when each front door is opened and closed?
When the driver's door is opened and closed, scan tool MB991502 does not sound.: Go to Step 2.
When the front passenger's door is opened and closed, scan tool MB991502 does not sound.: Go to Step 6.
When each front door is opened and closed, scan tool MB991502 sounds.: Replace the ETACS-ECU. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the driver's or the front passenger's door switch should be normal.







STEP 2. Check the driver's door switch.

Remove the driver's door switch. Then check the continuity between the switch terminals and the switch body.

Q: Is the driver's door switch in good condition?

YES: Go to Step 3.

NO: Replace the front door switch (LH). If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the driver's door switch should be normal.




STEP 3. Measure at the lower metal part of the driver's door switch in order to check the ground circuit to the driver's door switch.

NOTE: Check that the driver's door switch is grounded to the vehicle body by means of its mounting screw.
Remove the cap, and measure the resistance value between the lower metal part and the ground.

- The measured value should be 2 Ohm or less.

Q: Does the measured resistance value correspond with this range?

YES: Go to Step 4.

NO: Check the fit of the switch, and repair if necessary. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the driver's door switch should be normal.







STEP 4. Check driver's door switch connector D-18 and ETACS-ECU connector C-226 for damage.

Q: Are driver's door switch connector D-18 and ETACS-ECU connector C-226 in good condition?

YES: Go to Step 5.

NO: Repair or replace the connector. Refer to Harness Connector Inspection. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the driver's door switch should be normal.










STEP 5. Check the wiring harness between driver's door switch connector D-18 and ETACS-ECU connector C-226.

NOTE: Also check junction block connector C-217. If junction block connector C-217 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between driver's door switch connector D-18 and ETACS-ECU connector C-226 in good condition?

YES: Replace the ETACS-ECU. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the driver's door switch should be normal.

NO: Repair the wiring harness. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the driver's door switch should be normal.







STEP 6. Check the front passenger's door switch.

Remove the front passenger's door switch. Then check the continuity between the switch terminals and the switch body.

Q: Is the front passenger's door switch in good condition?

YES: Go to Step 7.

NO: Replace the front passenger's door switch. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the front passenger's door switch should be normal.




STEP 7. Measure at the lower metal part of the passenger's door switch in order to check the ground circuit to the front passenger's door switch.

NOTE: Check that the front passenger's door switch is grounded to the vehicle body by means of its mounting screw. Remove the cap, and measure the resistance value between the lower metal part and the ground.

- The measured value should be 2 Ohm or less.

Q: Does the measured resistance value correspond with this range?

YES: Go to Step 8.

NO: Check the fit of the switch, and repair if necessary. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the front passenger's door switch should be normal.







STEP 8. Check front passenger's door switch connector D-01 and ETACS-ECU connector C-228 for damage.

Q: Are front passenger's door switch connector D-01 and ETACS-ECU connector C-228 in good condition?

YES: Go to Step 9.

NO: Repair or replace the connector. Refer to Harness Connector Inspection. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the front passenger's door switch should be normal.










STEP 9. Check the wiring harness between front passenger's door switch connector D-01 and ETACS-ECU connector C-228.

NOTE: Also check intermediate connector C-113. If intermediate connectors C-113 is damaged, repair or replace the connector as described in Harness Connector Inspection.

Q: Is the wiring harness between front passenger's door switch connector D-01 and ETACS-ECU connector C-228 in good condition?

YES: Replace the ETACS-ECU. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the front passenger's door switch should be normal.

NO: Repair the wiring harness. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the front passenger's door switch should be normal.