EPS DTC Troubleshooting: 21-01, 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 indicator is on, troubleshoot the PGM-FI system 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.
  1. Turn the ignition switch OFF.
  1. Connect the HDS to the 16P data link connector (DLC).
  1. Start the engine, run the vehicle in the 4th gear.
  1. Check the VEL 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 .
  1. Check for DTCs in the PGM-FI system DTCs MANU with the HDS.
Is DTC P0720 indicated?
YES -
Troubleshoot the indicated DTC.■
NO -
Go to Step 7 .
  1. Start the engine and check the tachometer.
Is the tachometer working correctly?
YES -
Go to Step 8 .
NO -
  1. Turn the ignition switch OFF.
  1. Disconnect ECM connector No. 2 (58P) and EPS control unit connector D (28P).
  1. Check for continuity between EPS control unit connector D (28P) terminals No. 1 and ECM connector No. 2 (58P) terminals No. 47.
Is there continuity?
YES -
Go to Step 11 .
NO -
Repair open in the wire between the EPS control unit and the ECM.■
  1. Check for continuity between EPS control unit connector D (28P) terminals No. 15 and ECM connector No. 2 (58P) terminals No. 48.
Is there continuity?
YES -
Check for loose terminals in the EPS control unit connector D (28P), 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.■