P0122 – Throttle Position Sensor (Main) Circuit Low Input 3A9 MMC Colt

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OPERATION

A power voltage of 5 V is applied to the electronic-controlled throttle valve (terminal No. 5) from the engine-ECU (terminal No. 31).

The power voltage is earthed to the engine-ECU (terminal No. 30) from the electronic-controlled throttle valve (terminal No. 3).

The sensor signal is inputted to the engine-ECU (terminal No. 15) from the electronic-controlled throttle valve output terminal (terminal No. 4).

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FUNCTION

The throttle position sensor converts the throttle valve position into voltage and inputs it into the engine-ECU.

The engine-ECU controls the throttle valve position.

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TROUBLE JUDGMENT

Ignition switch is in “ON” position.

Throttle position sensor (main) output voltage is 0.35 V or less for 0.5 second.

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PROBABLE CAUSES

Failed throttle position sensor (main)

Open or shorted throttle position sensor (main) circuit, harness damage, or connector damage

Failed engine-ECU

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DIAGNOSIS PROCEDURE

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

Item No. 13: Throttle position sensor (main)

Q. Is the check result normal?

STEP 2. Connector check: A-118 electronic-controlled throttle valve connector and A-08 engine-ECU connector

Q. Are the check results normal?

STEP 3. Check harness between A-118 (terminal No. 5) electronic-controlled throttle valve connector and A-08 (terminal No. 31) engine-ECU connector.

Check power supply line for damage.

Q. Is the check result normal?

STEP 4. Check harness between A-118 (terminal No. 4) electronic-controlled throttle valve connector and A-08 (terminal No. 15) engine-ECU connector.

Check output line for short circuit.

Q. Is the check result normal?

STEP 5. M.U.T.-III data list

Item No. 13: Throttle position sensor (main)

Q. Is the check result normal?

STEP 6. Replace the throttle body assembly

After replacing the throttle body assembly, reconfirm whether the diagnosis code is set.

Q. Is the diagnosis code set?