Faulty Signal. Permanent Fault

Checking the Speedometer
- Test drive the car.
- Check that speedometer is operating correctly.

If reading is OK:
^ Proceed to: Checking Vehicle Speed Signal section below.

If reading is incorrect:
^ Fault-trace combined instrument panel and vehicle speed sensor (VSS) circuit.
^ Proceed to: Verification section below.





Checking Vehicle Speed Signal
- Connect the breakout box and check ground terminals.
- Connect engine control module (ECM).
- Gear selector in Neutral.
- Jack up the car so that the rear wheels can turn freely.
- Ignition ON.
- Connect a voltmeter between connectors # 18 (# B18) and # 28 (# B28) on the breakout box.
- Rotate the rear wheels.

NOTE: When the front wheels are stationary and the rear wheels rotate diagnostic trouble codes (DTCs) may can be stored in the ABS system. Erase diagnostic trouble codes in the ABS system.

- The voltmeter reading should oscillate between approx. 0.5 Volts and battery voltage.

If reading is OK:
^ The cause of the diagnostic trouble code has been loose connections in the engine control module connector.
^ Check connector for contact resistance and oxidation and remedy.
^ Proceed to: Verification section below.

If reading is incorrect:
^ Proceed to: Checking Signal Cable Voltage section below.





Checking Signal Cable Voltage
- Breakout box connected.
- Gear selector in Neutral.
- Jack up the car so that the rear wheels can turn freely.
- Ignition ON.
- Connect a voltmeter between connectors #18 (#B18) and #28 (#B28) on the breakout box.
- Rotate the rear wheels.
- The voltmeter reading should oscillate between approx. 0.5 Volts and battery voltage.

Alternative 0 Volts:
^ Check cable between the combined instrument panel terminal A7 and engine control module # B18 for a short-circuit to ground.

Alternative 5 Volts:
^ Proceed to: Checking the Signal Cable section below.





Checking the Signal Cable
- Breakout box connected.
- Ignition ON.
- Connect an electrician's screwdriver (3 W bulb at least) between terminals # 18 (# B18) and # 28 (# B28) on the breakout box.
- The electrician's screwdriver should not light.

If reading is OK:
^ Check cable between the combined instrument panel terminal D:1 and engine control module # B18 for an open-circuit.
^ Proceed to: Verification section below.

If reading is incorrect:
^ Check cable between combined instrument panel terminal D:1 and engine control module # B18 for a short-circuit to supply voltage.
^ Proceed to: Verification section below.





Verification
After carrying out the repair, check that the fault has been remedied as follows:

- Ignition OFF.
- Control module connected.
- Combined instrument panel connected.
- Test drive the car.
- Go into scrolling values.
- Read off the speedometer signal.
- Is the correct vehicle speed signal displayed?

Yes:
^ Fault corrected.

No:
^ Proceed to: Fault-tracing Information section below.

Fault-tracing Information
The verification result shows that the fault persists.

- Do you want to exit fault-tracing?

Yes:
^ Fault not corrected.

No:
^ Proceed to: Checking the Speedometer section above.