DTC 21-01

DTC 21-01: Excessive Change of the Vehicle Speed Signal (Regular Diagnosis)

DTC 21-02: Comparison between the Vehicle Speed and the Engine Speed Signal (Regular Diagnosis)

NOTE:
^ If the MIL indicator is on, troubleshoot the fuel and emissions systems first.
^ Even though the system is operating normally, the EPS indicator will come on caused by the detecting condition of DTC 21-01 or DTC 21-02.
^ Clear the DTC related to the ABS or ABS/VSA.

1. Turn the ignition switch to LOCK (0).
2. Raise the vehicle, and support it with safety stands in the proper locations, and allow all wheels to rotate freely.
3. Connect the HDS to the data link connector (DLC).
4. Start the engine, run the vehicle in 4th.
5. Check the VEHICLE SPEED in the DATA LIST with the HDS.

Is the vehicle speed indicated?

YES - The system is OK at this time.

NO - Go to step 6.

6. Check for DTCs in the fuel and emissions systems with the HDS.

Is DTC P0720 indicated?

YES - Troubleshoot the indicated DTC.

NO - Go to step 7.

7. Start the engine and check the tachometer.

Is the tachometer working correctly?

YES - Go to step 8.

NO - Troubleshoot the gauge control module (tach).

8. Turn the ignition switch to LOCK (0).
9. Short the SCS line with the HDS.
10. Disconnect ECM connector A (44P) and EPS control unit connector D (28P).
11. Check for continuity between EPS control unit connector D (28P) terminals No. 1 and ECM connector A (44P) terminals No. 36.





Is there continuity?

YES - Go to step 12.

NO - Repair open in the wire between the EPS control unit and the ECM.

12. Check for continuity between EPS control unit connector D (28P) terminals No. 15 and ECM connector A (44P) terminals No. 37.





Is there continuity?

YES - Check for loose terminals in the EPS control unit connectors, and repair if necessary. If no poor connections are found, replace the EPS control unit.

NO - Repair open in the wire between the EPS control unit and the ECM.