Code No. P0820: Neutral Position Sensor System <Vehicles with AS&G system>

OPERATION

A power voltage of 5 V is applied to the neutral position sensor power terminal (terminal No. 3) from the engine-ECU (terminal No. 41) and earthed to the engine-ECU (terminal No. 26) from the neutral position sensor (terminal No. 4).
The sensor signal is inputted to the engine-ECU (terminal No. 11) from the neutral position sensor output terminal (terminal No. 1).

FUNCTION

The neutral position sensor outputs the duty signal according to the shift lever position.
In response to the signal, the engine-ECU controls the AS&G system.

TROUBLE JUDGMENT

Check Conditions

2 seconds later after the ignition switch has been in "ON" position or the engine has started up.
The battery voltage is more than 8 V and is less than 16 V.

Judgment Criterion

For 2 seconds, the falling signal from the neutral position sensor is not detected.

For 2 seconds, the time from the neutral position sensor per cycle is lower than 3.5ms or more than 4.5 ms.

PROBABLE CAUSES

Failed neutral position sensor
Open or shorted neutral position sensor circuit, harness damage, or connector damage

Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

Refer to Data List Reference Table .

Item No. 163: Neutral position sensor

Q. Is the check result normal?

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

	Go to Step 2 .

STEP 2. Connector check: A-146 neutral position sensor connector

Q. Is the check result normal?

Go to Step 3 .

Repair or replace the connector.

STEP 3. Perform voltage measurement at A-146 neutral position sensor connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 3 and earth.

OK: 4.9 - 5.1 V

Q. Is the check result normal?

Go to Step 7 .

Go to Step 4 .

STEP 4. Connector check: A-08 engine-ECU connector

Q. Is the check result normal?

Go to Step 5 .

Repair or replace the connector.

STEP 5. Check harness between A-146 (terminal No. 3) neutral position sensor connector and A-08 (terminal No. 41) engine-ECU connector.

Check power supply line for open/short circuit.

Q. Is the check result normal?

Go to Step 6 .

Repair the damaged harness wire.

STEP 6. M.U.T.-III data list

Refer to Data List Reference Table .

Item No. 163: Neutral position sensor

Q. Is the check result normal?

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

	Replace the engine-ECU then perform the variant coding (Refer to GROUP 00 - Precautions Before Service - How to Perform Variant Coding ).

STEP 7. Perform resistance measurement at A-146 neutral position sensor connector.

Disconnect connector, and measure at harness side.
Resistance between terminal No. 4 and earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

Go to Step 10 .

Go to Step 8 .

STEP 8. Connector check: A-08 engine-ECU connector

Q. Is the check result normal?

Go to Step 9 .

Repair or replace the connector.

STEP 9. Check harness between A-146 (terminal No. 4) neutral position sensor connector and A-08 (terminal No. 26) engine-ECU connector.

Check earthing line for open circuit and damage.

Q. Is the check result normal?

Go to Step 6 .

Repair the damaged harness wire.

STEP 10. Connector check: A-08 engine-ECU connector

Q. Is the check result normal?

Go to Step 11 .

Repair or replace the connector.

STEP 11. Check harness between A-146 (terminal No. 3) neutral position sensor connector and A-08 (terminal No. 41) engine-ECU connector.

Check power supply line for damage.

Q. Is the check result normal?

Go to Step 12 .

Repair the damaged harness wire.

STEP 12. Perform voltage measurement at A-08 engine-ECU connector.

Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB991987), and then measure the voltage on the check connector.
Ignition switch: ON
Voltage between terminal No. 11 and earth.

OK: The wave form such as the check procedure () with the oscilloscope must be output. When the shift lever is placed into the 1st, 3rd and 5th positions; or when it is placed into 2nd, 4th and reverse positions, the wave form must be changed. The output waveform must not have the noise waveform.

Q. Is the check result normal?

Go to Step 6 .

Go to Step 13 .

STEP 13. Check harness between A-146 (terminal No. 1) neutral position sensor connector and A-08 (terminal No. 11) engine-ECU connector.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

Replace the neutral position sensor.

Repair the damaged harness wire.