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Inspection Procedure 1: Cannot communicate with KOS-ECU using the scan tool.
 
 
cautionBefore replacing the ECU, ensure that the communication circuit is normal.
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the M.U.T.-III cannot communicate with the KOS-ECU, the CAN bus lines may be defective. If the KOS-ECU does not work, the KOS-ECU or the power supply circuit may be defective.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of the power supply or ground of KOS-ECU
  • Malfunction of CAN bus line
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
(1)
cautionTo prevent damage to scan tool MB991958, always turn the power supply mode of the engine switch to the OFF position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958. Refer to "How to connect scan too (M.U.T.-III) ."
(2) Turn the power supply mode of the engine switch to ON.
(3) Diagnose the CAN bus line.
(4) Turn the power supply mode of the engine switch to OFF.
Is the CAN bus line found to be normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C, Diagnosis ).
 
STEP 2. Check the power supply circuit and the ground circuit to KOS-ECU.
Refer to Inspection Procedure 3 "Abnormality in KOS-ECU power supply and ground circuits" .
Is the power supply circuit and the ground circuit to KOS-ECU in good condition ?
Go to Step 3.
Repair the power supply circuit and the ground circuit to KOS-ECU.
 
STEP 3. Retest the system
Check if scan tool can communicate with KOS-ECU.
Does the scan tool cannot with KOS-ECU?
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 KOS-ECU and register the ID codes (Refer to ).