Code No. P0606: Engine-ECU Main Processor Malfunction

OPERATION

Check Inspection Procedure - engine-ECU power supply, engine control relay, ignition switch-IG1 system (Refer to ).

FUNCTION

The engine-ECU check whether the microcomputer, which performs the drive control of the throttle valve, is normal.

TROUBLE JUDGEMENT

Check Condition

Ignition switch is "ON" position.

Judgement Criterion

No surveillance pulse signals should be input.

FAIL-SAFE AND BACKUP FUNCTION

Throttle opening degree position is in default position.

PROBABLE CAUSES

Short circuit in the engine control relay circuit or loose connector contact.
Open/short circuit or harness damage in the ignition switch (IG1) circuit or loose connector contact.
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check battery.

Battery check (Refer to GROUP 54A - Battery - On-vehicle Service - Battery Test ).

Q. Is the check result normal?

	Go to Step 2.

	Replace the battery.

STEP 2. Perform voltage measurement at engine-ECU connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal IGN and earth.

OK: System voltage

Q. Is the check result normal?

	YES : Go to Step 3.

	NO : Repair or replace the connector(s), or check and repair the harness of open circuit, and short to earth in IGN line between ignition switch connector (IG1) and engine-ECU connector.

STEP 3. Check of damage in IGN line between ignition switch connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 4.

	Repair the connector(s) or wiring harness.

STEP 4. Check engine control relay itself.

Engine control relay connector check.
Engine control relay continuity check (Refer to ).

Q. Is the check result normal?

	Go to Step 5.

	Repair or replace the connector, or replace the engine control relay.

STEP 5. Check of short in C/R line between engine control relay connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 6.

	Repair the connector(s) or wiring harness.

STEP 6. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Q. Is diagnosis code set?

	Replace the engine-ECU.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).