Speed Signal, Checking

Speed Signal, Checking

Test requirement

• Function and display of speedometer OK.

CAUTION!
To reduce the risk of accident during road tests, always observe safety precautions Page 24-1.

- Connect the scan tool.

- Start the engine and let run at idle.

- Select "Diagnostic Mode 01 - Obtain Data".

- Select the measured value "PID 13: Vehicle speed".

- Perform a road test, and have the 2nd person observe the indication on the display.

- Check the specified value of the vehicle speed:





- End the diagnosis and switch ignition off.

If no speed is displayed:

The speed signal is transferred from the Engine Control Module (ECM) (J623) to the instrument cluster by wire connection or by CAN-Bus, depending on version.

- Check the wiring connections.

- Check the terminal resistance for the CAN-Bus => [ CAN-Bus Terminal Resistance, Checking ] CAN-Bus Terminal Resistance, Checking.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code, Setting ] Readiness Code, Setting.

End of Diagnosis.