When replacing
the ECU, always check that the communication circuit is normal.
DIAGNOSTIC FUNCTION
When a short circuit of starter setting circuit system is detected, KOS&OSS-ECU
sets diagnosis code No.B1131. At the same time, KOS&OSS-ECU displays the power supply
system error warning to the combination meter, and flashes the indicator of engine switch in
orange.
JUDGEMENT CRITERIA
Check Conditions
After KOS&OSS-ECU activation
Judgement Criterion
Starter setting circuit system is detected
PROBABLE CAUSES
Damaged wiring harness or connector (short to earth or
short to power supply in STO line)
Malfunction of KOS&OSS-ECU
Malfunction of engine-ECU
DIAGNOSIS PROCEDURE
STEP 1. Check of short to power supply, short to earth
or open circuit in STO line between KOS&OSS-ECU connector and engine-ECU connector
Q.
Is the check result normal?
Go to Step 2.
Repair the connector(s) or wiring harness.
STEP 2. Voltage measurement at engine-ECU connector (ST terminal)
(1)Disconnect the engine-ECU connector, and measure at the wiring harness side.
(2)Using the M.U.T.-III, set the forced power supply output to other than "IG-ST"
(Refer to ).
(3)Measure the voltage between the engine-ECU connector (ST terminal) and body earth. OK: 1 V or less
(4)Using the M.U.T.-III, set the forced power supply output to "IG-ST" (Refer to ).
(5)Measure the voltage between the engine-ECU connector (ST terminal) and body earth. OK: System voltage
Q.
Is the check result normal?
Go to Step 3.
NO :
STEP 3. Check whether the diagnosis code is set again.
Check again if the diagnosis code is set in the KOS&OSS-ECU.
(1)Erase the diagnosis code.
(2)Turn the engine switch from "LOCK" (OFF) position to "ON" position.
(3)On completion, check that the diagnosis code is set again.
Q.
Is the diagnosis code set?
Replace the engine-ECU and register the chassis number and key codes [Refer
to GROUP 00 - How to Perform Chassis Number (Chassis No.) Writing ].
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).