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Inspection Procedure 1: The ignition switch (ACC) signal is not received.
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TECHNICAL DESCRIPTION (COMMENT)
If there is an error to the input signal (ACC) from the OSS-ECU, 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
  • The OSS-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
  • MB992006: Extra Fine Probe
STEP 1. Voltage measurement at ETACS-ECU connector (ACC terminal).
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Turn the electric motor switch to the "ACC" position.
(3) Check the voltage between the ETACS-ECU connector (ACC terminal) and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 4.
Go to Step 2.
 
STEP 2. Using scan tool (M.U.T.-IIISE), read the OSS DTC.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Press the electric motor switch to turn on the power supply mode.
(3) Check whether the OSS-ECU sets a DTC.
Is the DTC set?
Diagnose the OSS-ECU. Refer to GROUP 42B, Troubleshooting .
Go to Step 3.
 
STEP 3. Check of short to power supply, short to ground, and open circuit in ACC OSS-ECU (ACC) and ETACS-ECU connector.
Is the check result normal?
Go to Step 4.
Repair the connector(s) or wiring harness.
 
STEP 4. Using scan tool (M.U.T.-IIISE), check data list.
Check the input signals from the OSS-ECU (ACC).
  • Turn the electric motor switch to the ACC position.
 
Item No.Item nameNormal condition
288ACC switchON
OK: Normal condition is displayed.
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 ).
Replace the ETACS-ECU.