DTC 21-02

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 stays on, or the D indicator blinks (A/T model) at the same time as DTC 21-01 or DTC 21-02 is indicated, troubleshoot the PGM-FI system or the automatic transmission system first, then recheck for DTC 21-01 or DTC 21-02.
^ 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.

1. Start the engine.
2. Check the ENGINE SPEED in the EPS DATA LIST with the HDS.

Is 0 rpm indicated?

YES - Go to step 22.

NO - Go to step 3.

3. Turn the ignition switch OFF.
4. Raise the vehicle, and support it with safety stands in the proper locations, and allow all wheels to rotate freely.
5. Start the engine, then run the vehicle in 4th gear (M/T model), or the D position (A/T model).
6. Check the VEHICLE SPEED in the EPS DATA LIST with the HDS.

Is 0 mph (km/h) indicated?

YES - Go to step 7.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the vehicle speed sensor (VSS) (M/T model), or the PCM (A/T model) and the EPS control unit.

7. Turn the ignition switch OFF.
8. M/T model: Disconnect the vehicle speed sensor (VSS) 3P connector and gauge control module connector C (40P).
9. A/T model: Short the SCS line with the HDS.
10. A/T model: Disconnect PCM connector E (31P).
11. Disconnect audio unit connector A (17P).
12. Disconnect EPS control unit connector D (28P).
13. Turn the ignition switch ON (II).
14. Measure voltage between body ground and EPS control unit connector D (28P) terminal No. 5.





Is there 0.1 V or more?

YES
^ M/T model: Repair short to power in the wire between the EPS control unit, the vehicle speed sensor (VSS), the gauge control module, and the audio unit.
^ A/T model: Repair short to power in the wire between the EPS control unit, the PCM, and the audio unit.

NO - Go to step 15.

15. Turn the ignition switch OFF.
16. Check for continuity between body ground and EPS control unit connector D (28P) terminal No. 5.





Is there continuity?

YES -
^ M/T model: Repair short to ground in the wire between the EPS control unit, the vehicle speed sensor (VSS), the gauge control module, and the audio unit.
^ A/T model: Repair short to ground in the wire between the EPS control unit, the PCM, and the audio unit.

NO -
^ M/T model: Go to step 17.
^ A/T model: Go to step 18.

17. Check for continuity between vehicle speed sensor (VSS) 3P connector terminal No. 3 and EPS control unit connector D (28P) terminal No. 5.





Is there continuity?

YES - Go to step 19.

NO - Repair open in the wire between the EPS control unit and the vehicle speed sensor (VSS).

18. Check for continuity between PCM connector E (31P) terminal No. 26 and EPS control unit connector D (28P) terminal No. 5.





Is there continuity?

YES - Go to step 19.

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

19. Reconnect all connectors.
20. Start the engine.
21. While the drive wheels are stopped, measure voltage between body ground and EPS control unit connector D (28P) terminal No. 5. Continue measuring the voltage while the drive wheels are running with the vehicle in 4th gear (M/T model) or the D position (A/T model).





Does the voltage change from 0 V with wheels stopped to about 2.5 V with the vehicle running?

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 -
^ M/T model: Check for poor connections or loose terminals at the vehicle speed sensor (VSS). If necessary, substitute a known-good vehicle speed sensor (VSS) and recheck.
^ A/T model: Check for poor connections or loose terminals at the PCM. If necessary, substitute a known-good PCM and recheck.

22. Turn the ignition switch OFF.
23. Disconnect EPS control unit connector D (28P).
24. Start the engine.
25. Measure voltage between body ground and EPS control unit connector D (28P) terminal No. 3.





Is there any voltage?

YES - Go to step 26.

NO - Go to step 31.

26. Turn the ignition switch OFF.
27. Short the SCS line with the HDS.
28. Disconnect ECM/PCM connector E (31P).
29. Turn the ignition switch ON (II).
30. Measure voltage between body ground and EPS control unit connector D (28P) terminal No. 3.





Is there 0.1 V or more?

YES - Repair short to power in the wire between the EPS control unit and the ECM/PCM.

NO - 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.

31. Turn the ignition switch OFF.
32. Short the SCS line with the HDS.
33. Disconnect ECM/PCM connector E (31P).
34. Check for continuity between body ground and EPS control unit connector D (28P) terminal No. 3.





Is there continuity?

YES - Repair short to body ground in the wire between the EPS control unit and the ECM/PCM.

NO - Go to step 35.

35. Check for continuity between ECM/PCM connector E (31P) terminal No. 25 and EPS control unit connector D (28P) terminal No. 3.





Is there continuity?

YES - Check for poor connections or loose terminals at the ECM/PCM. If necessary, substitute a known-good ECM/PCM and recheck.

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