Speed Signal, Checking
The following procedure requires a test drive. Observe all safety precautions. Refer to SAFETY PRECAUTIONS .
Special Tools And Workshop Equipment Required
- Multimeter.
- Wiring diagram.
Test Requirements
- The Speedometer -G21- OK.
- The Engine Control Module (ECM) -J623- fuses OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- A/C switched off.
- Ground connections between engine/transmission/chassis OK.
- Ignition switched off.
Test Procedure
-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK
Start Diagnosis
-- Connect the scan tool.
-- Perform a road test with a vehicle speed greater than 5 Km/h.
-- Using the scan tool, Check the vehicle speed:
| Diagnostic text | Specified value | |||
|---|---|---|---|---|
| Vehicle Speed | Approx. Vehicle Speed | |||
-- Compare the vehicle speed on the scan tool to the Speedometer -G21-.
Specified Value: A Difference Of No Greater Than 10%.
If The Specified Value Was Not Obtained Or No Speed Was Displayed:
-- For models with ABS, check the wheel speed signal in the ABS controller with a scan tool. If the signal is not present or a code is set, refer to the ABS diagnostics in the Repair Manual.
-- On other models check the wiring from the Engine Control Module (ECM) -J623- to the Instrument Cluster Control Module -J285- for an open circuit, Short to Battery (+), or to Ground.
-- Check the wiring connection for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
Final Procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .