Inspection Procedure 2: Malfunction of the ignition switch (IG1) input/output signal

TECHNICAL DESCRIPTION (COMMENT)

If there is an error to the ignition switch (IG1) input signal, or the IG1 relay inside the ETACS-ECU does not operate, the ignition switch (IG1) signal is no longer output to the communication line.

TROUBLESHOOTING HINTS

The ignition switch may be defective
The ETACS-ECU may be defective
The fuse 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
MB992006: Extra Fine Probe

STEP 1. Check ETACS-ECU connector C-317 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is ETACS-ECU connector C-317 in good condition?

	Go to Step 2.

	Repair or replace the damaged component(s) (Refer to GROUP 00E, Harness Connector Inspection ). Check that the input signal of ignition switch (IG1) is normal.

STEP 2. Check the ignition switch (IG1) line of the power supply circuit to the ETACS-ECU. Measure the voltage at ETACS-ECU connector C-317.

(1)Disconnect ETACS-ECU connector C-317 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 6 and ground.

The voltage should measure approximately 12 volts (battery positive voltage).

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

Go to Step 5.

Go to Step 3.

STEP 3. Check the ignition switch.

Remove the ignition switch. Then check continuity between the switch terminal.

Ignition key position	Terminal number	Normal condition
LOCK	1 - 2, 1 - 4, 1 - 5, 1 - 6	No continuity
ACC	1 - 6	Continuity exists (2 ohms or less)
ON	1 - 2 - 4 - 6	Continuity exists (2 ohms or less)
START	1 - 2 - 5	Continuity exists (2 ohms or less)

Q. Is the ignition switch in good condition?

Go to Step 4.

Replace the ignition switch. Check that the input signal of ignition switch (IG1) is normal.

STEP 4. Check the wiring harness between ETACS-ECU connector C-317 (terminal 6) and the ignition switch (IG1).

Check the power supply line (IG1) for open circuit and short circuit.

Q. Is the wiring harness between ETACS-ECU connector C-317 (terminal 6) and ignition switch (IG1) in good condition?

	Go to Step 5.

	The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. Check that the input signal of ignition switch (IG1) is normal.

STEP 5. Using scan tool MB991958, check data list.

Ignition switch: ON

Item No.	Item name	Normal condition
Item 254	IG voltage	Battery positive voltage

OK: Normal condition is displayed.

Q. Is the check result normal?

	The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points, How to Cope with Intermittent Malfunction ).

	Refer to Inspection Procedure 2 "Defective power supply system of the ignition switch"