Inspection Procedure O-2

The ETACS-ECU does not Receive Any Signal from the Ignition Switch (IG1).

Ignition Switch (IG1) Input Circuit Part 1:

CIRCUIT OPERATION
- The ETACS-ECU operates the following equipment or functions according to signal from the ignition switch (IG1):
- Ignition key reminder tone alarm function
- Light reminder tone alarm function
- Seat belt tone alarm function
- Power window timer function
- Seat belt warning light
- Headlight automatic shutdown function
- Turn-signal light
- Dome light dimming function
- If the power supply circuit from the battery to the ETACS-ECU is open, this circuit is used as backup circuit.

TECHNICAL DESCRIPTION (COMMENT)
If the signal is not normal, the equipment or functions, which are described in "CIRCUIT OPERATION", do not work normally.

TROUBLESHOOTING HINTS
- The ETACS-ECU may be defective
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicles communication interface (V.C.I.)
- MB991827: MUT-III USB cable
- MB991911: MUT-III Main harness B




STEP 1. Check ETACS-ECU connector C-119 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Is ETACS-ECU connector C-119 in good condition?

YES: Go to Step 2.

NO: Repair or replace the damaged component(s). Refer to Harness Connector Inspection. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the ignition switch (IG1) should be normal.

STEP 2. Check the ignition switch (IG1) circuit to the ETACS-ECU. Measure the voltage at ETACS-ECU connector C-119.




1. Disconnect ETACS-ECU connector C-119 and measure the voltage available at the junction block side of the connector.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between terminal 8 and ground.
- The voltage should equal approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approximately 12 volts (battery positive voltage)?

YES: Replace the ETACS-ECU. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the ignition switch (IG1) should be normal.

NO: Go to Step 3.







STEP 3. Check the wiring harness between ETACS-ECU connector C-119 (terminal 8) and the ignition switch (IG1).

NOTE: Also check junction block connector C-111 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If junction block connector C-111 is damaged, Repair or replace the damaged component(s) as described in Harness Connector Inspection.

Q: Is the wiring harness between ETACS-ECU connector C-119 (terminal 8) and ignition switch (IG1) in good condition?

YES: No action is necessary and testing is complete.

NO: Repair the wiring harness. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the ignition switch (IG1) should be normal.