Inspection Procedure 1

Inspection Procedure 1: ETACS-ECU does not receive any signal from the ignition switch (ACC).














TECHNICAL DESCRIPTION (COMMENT)

If there is an error to the input signal (ACC) from the ignition switch [Vehicles without KOS] or OSS-ECU [Vehicles with KOS], or if the ACC relay in ETACS-ECU does not function normally, the ignition switch (ACC) signal is no longer output to the communication line.

TROUBLESHOOTING HINTS

- The ETACS-ECU may be defective
- Malfunction of the ignition switch[ Vehicles without KOS]
- Malfunction of the OSS-ECU[ Vehicles with KOS]
- 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-417 or OSS-ECU connector C-14 [Vehicles with KOS] for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is ETACS-ECU connector C-417 or OSS-ECU connector C-14[ Vehicles with KOS] in good condition?

YES [Vehicles without KOS] : Go to Step 2.
YES [Vehicles with KOS] : Go to Step 3.
NO : Repair or replace the damaged component(s). Harness Connector Inspection. Check that the input signal of ignition switch (ACC) is normal.
STEP 2. Check the ignition switch.

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





Q. Is the ignition switch in good condition?

YES Go to Step 3.
NO Replace the ignition switch. Check that the input signal of ignition switch (ACC) is normal.
STEP 3. Check the ignition switch (ACC) line of the power supply circuit to the ETACS-ECU. Measure the voltage at ETACS-ECU connector C-417.

(1)Measure by backprobing without disconnecting the connector.

(2)Turn the ignition switch to the "ACC" position.





(3)Measure the voltage between the terminal No.7 and the ground.

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

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

YES Go to Step 5.

NO Go to Step 4.

STEP 4. Check the wiring harness between ETACS-ECU connector C-417
(terminal 7) and the ignition switch (ACC) [Vehicles without KOS] or OSS-ECU connector C-14 (terminal 10) [Vehicles with KOS].

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

Q. Is the wiring harness between ETACS-ECU connector C-417 (terminal 7) and the ignition switch (ACC)[ Vehicles without KOS] or OSS-ECU connector C-14 (terminal 10)[ Vehicles with KOS] in good condition?

YES [Vehicles without KOS] : Troubleshoot the ignition switch. Refer to Inspection Procedure 2 "Malfunction of the ignition switch power supply system" Symptom Chart.
YES [Vehicles with KOS] : Troubleshoot the OSS. Inspection Procedure 3.
NO : 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 (ACC) is normal.
STEP 5. Using scan tool MB991958, check data list.

- Ignition switch: ACC





OK: Normal condition is displayed.


Q. Is the check result normal?

YES The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the ETACS-ECU.