Speed Signal, Checking

Speed Signal, Checking

Test requirement:
- Function and display of speedometer OK. Troubleshooting.

WARNING: To reduce the risk of accident during road tests, always observe safety precautions.

- Connect diagnostic tester.
- Start engine and let run at idle.
- In diagnostic function "33 - OBD", select "Diagnostic mode 1 - Check measuring values".
- Select the desired measuring value "PID 13: Vehicle speed".
- Perform a road test, and have the 2nd person observe the indication on the display.







- End diagnosis and switch ignition off.

If no speed is displayed:

The speed signal is transferred from the Engine Control Module (ECM) to the instrument cluster via wire connection or via CAN-Bus, depending on version.
- Checking wire connections
- Check terminal resistance for CAN-Bus

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check DTC memory see "Mode 3: Check DTC memory". Mode 3: Check DTC Memory
2. If necessary, erase DTC memory see "Mode 4: Reset/erase diagnostic data". Mode 4: Reset/Erase Diagnostic Data
3. Generate readiness code. Readiness Code, Generating