[Previous][Next]
Inspection Procedure 2: The ignition switch (IG1) signal is not received.
 
 
cautionWhenever the ECU is replaced, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the input signal from the ignition switch (IG1) is defective, the signal is not sent to the communication lines.
 
 
TROUBLESHOOTING HINTS
  • The ETACS-ECU may be defective
  • The OSS-ECU may be defective <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. Voltage measurement at ETACS-ECU connector (IG1 terminal)
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Check the voltage between the ETACS-ECU connector (IG1 terminal) and ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage).
Is the check result normal?
Go to Step 5.
<vehicles without KOS> : Go to Step 2.
<vehicles with KOS> : Go to Step 3.
 
STEP 2. Check of short to power supply, short to ground, and open circuit in IG1 line between ignition switch (IG1) and ETACS-ECU connector
Is the check result normal?
Refer to Inspection Procedure "Malfunction of the ignition switch power supply system."
Repair the connector(s) or wiring harness.
 
STEP 3. Using scan tool (M.U.T.-III), read the OSS diagnostic trouble code
(1)
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
Connect scan tool (M.U.T.-III). Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(2) Turn the ignition switch to the "ON" position.
(3) Check that the OSS-ECU set a DTC.
Is the DTC stored?
Diagnose the OSS-ECU. Refer to GROUP 42B, Troubleshooting .
Go to Step 4.
 
STEP 4. Check of short to power supply, short to ground, and open circuit in IG1 line between IG1 relay connector and ETACS-ECU connector
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 ).
Repair the connector(s) or wiring harness.
 
STEP 5. Using scan tool (M.U.T.-III), check data list.
Check the input signal from the ignition switch (IG1).
  • Turn the ignition switch to the "ON" position.
 
Item No.Item nameNormal condition
30Ignition switch(IG1)ON
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.