Speed Signal, Checking
Special tools and workshop equipment required
- Multimeter VAG 1526 or Multimeter VAG 1715
- Connector test kit VAG 1594
- Wiring diagram
Test requirements
- Fuses in E-box (plenum chamber, left) must be OK: Refer to appropriate SYSTEMS WIRING DIAGRAM
- Motronic Engine Control Module (ECM) Power Supply Relay -J271- must be OK, check: appropriate SYSTEMS WIRING DIAGRAM
- Motronic Engine Control Module (ECM) Power Supply Relay 2 -J670- must be OK, check: appropriate SYSTEMS WIRING DIAGRAM
- Control module with indicator unit in instrument panel insert -J285- must be OK.
- Battery voltage must be at least 11.5 volts.
Function test
To check the speed signal, vehicle must be driven at a speed above 5 km/h.
Observe safety precautions that apply to road tests.
-- Connect diagnostic tester.
-- Start engine and let run at idle.
-- Under address word 33, select "Diagnostic mode 1: Checking measured values."
-- Select the measuring value "PID 13: Vehicle speed".
-- Perform a road test at a speed above 5 km/h while a 2nd person observes the indication on the display.
-- Check specified value of the vehicle speed:
| PID | Diagnostic text | Specified value: | ||||
|---|---|---|---|---|---|---|
| 13: | Vehicle speed | approx. vehicle speed | ||||
Vehicle speed must not drop to below 5 km/h during test.
-- End road test and switch ignition off.
If no speed is indicated:
-- Check wires according to wiring diagram.
Checking wiring
-- Connect test box to control module wiring harness, connect test box for wiring test.
-- Remove instrument cluster.
-- Check wire connection from Engine Control Module (ECM) to Control module with indicator unit in instrument panel insert -J285- according to wiring diagram: Refer to appropriate SYSTEMS WIRING DIAGRAM
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 .