Code No. P0502: Vehicle Speed Sensor Low Input




OPERATION



  • A power voltage of 5 V is applied to the vehicle speed sensor (terminal No. 3) from the engine-ECU (terminal No. 119).

FUNCTION



  • The vehicle speed sensor converts the vehicle speed to the voltage, and then input it into the engine-ECU

TROUBLE JUDGMENT


Check Conditions
  • Engine is running
  • Engine coolant temperature is 80°C or higher
  • The last fuel injection rate exceeds the specified value.
  • Engine speed is 2,900 r/min or more.
Judgment Criterion
  • Vehicle speed is 5 km/h or lower for 2 seconds.

PROBABLE CAUSES



  • Failed vehicle speed sensor
  • Open/short circuit in vehicle speed sensor circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the speed meter

Q. Is the check result normal?
Go to Step 2 .
Check the speed meter (Refer to GROUP 54A -Combination Meter - On-vehicle Service - Speedmeter Check ).

STEP 2. M.U.T.-III data list

  • Refer to Data list reference table .

  1. Item 04: Vehicle speed 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 3 .

STEP 3. Connector check: C-103 engine-ECU connector

Q. Is the check result normal?

Go to Step 4 .

Repair or replace the connector.

STEP 4. Check harness between C-103 (terminal No. 119) engine-ECU connector and B-01 (terminal No. 3) Vehicle speed sensor connector.


note Before checking harness, check intermediate connectors C-30, C-35 <R.H. drive vehicles>, C-53 <L.H. drive vehicles> and C-127, and repair if necessary.

  • Check output line for open circuit and damage.

Q. Is the check result normal?

Go to Step 5 .

Repair the damaged harness wire.

STEP 5. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is the diagnosis code set?
Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ).
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).