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

Detects a microcomputer malfunction 8 times consecutively.

Check Conditions

Ignition switch is "ON" position.
Battery positive voltage is more than 6.3 V.

Judgement Criterion

Throttle position sensor voltage is less than 4.1 V.

or

Malfunction of the main microcomputer basic voltage.

Check Conditions

Ignition switch is "ON" position.
Throttle position sensor (main) output voltage is more than 0.4 V and is less than 0.8 V.

Judgement Criterion

Malfunction of the throttle position sensor (main) input interface.

Check Condition

Ignition switch is "ON" position.

Judgement Criterion

When the RAM value is read after a specified value was written into RAM, the read value is not consistent with the written value.

Check Condition

Ignition switch is "ON" position.

Judgement Criterion

The error counter of ROM exceeds 100 times.

FAIL-SAFE AND BACKUP FUNCTION

Throttle opening degree position is in default position.
The RMS (Forward) and FCM-LS are prohibited. <Vehicles with FCM-LS>

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 <Vehicles without KOS> : Go to Step 3.

	YES <Vehicles with KOS> : Go to Step 4.

	NO <Vehicles without KOS> : 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.

	NO <Vehicles with KOS> : Repair or replace the connector(s), or check and repair the harness of open circuit, and short to earth in IGN line between IG1 relay connector 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 5.

	Repair the connector(s) or wiring harness.

STEP 4. Check of damage in IGN line between IG1 relay connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 5.

	Repair the connector(s) or wiring harness.

STEP 5. 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 6.

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

STEP 6. 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 7.

	Repair the connector(s) or wiring harness.

STEP 7. 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 ).