EPS

Control System DTCs

EPS DTC Troubleshooting: 21-01, 21-02

DTC 21-01 : Excessive Change of the Vehicle Speed Signal
DTC 21-02 : Comparison between the Vehicle Speed and the Engine Speed Signal

NOTE:
* If the MIL indicator is on, troubleshoot the fuel and emissions systems first.
* Even though the system is operating normally, the EPS indicator may come on with DTC 21-01 or DTC 21-02 when you raise the engine speed with the vehicle stopped.
* After completing repairs, do an All DTC check, and clear any related DTCs in other systems.

1. EPS system check:

EPS system check
-1. Turn the ignition switch to LOCK (0).

-2. Raise and support the vehicle Service and Repair, and allow all wheels to rotate freely.

-3. Connect the HDS to the data link connector (DLC).

-4. Start the engine.

-5. Turn off the VSA function by using the VSA OFF switch.

-6. Run the vehicle while in 4th gear (M/T), or D (A/T).

-7. Check the VEHICLE SPEED in the EPS DATA LIST with the HDS.

Is the vehicle speed indicated?
-YES- Intermittent failure, the system is OK at this time.
-NO- Go to step 2.

2. PGM-FI system (M/T) or A/T system (A/T) DTC check:

PGM-FI system (M/T) or A/T system (A/T) DTC check
-1. Check for DTCs in the PGM-FI system (M/T) or A/T system (A/T) with the HDS.

Is DTC P0720 (M/T), P0721 (A/T), P0722 (A/T), or P0723 (A/T) indicated?
-YES- Go to the indicated DTC's troubleshooting.
-NO- Go to step 3.

3. Gauge control module (tach) operation check:

Gauge control module (tach) operation check
-1. Start the engine, and check the tachometer.

Is the tachometer working correctly?
-YES- Go to step 5.
-NO- Go to step 4.

4. Gauge control module DTC check:

Gauge control module DTC check
-1. Check for DTCs in the gauge control module with the HDS.

Is DTC indicated?
-YES- Go to the indicated DTC's troubleshooting.
-NO- Go to step 7.

5. Open wire check (F_CAN-H line):

Open wire check (F_CAN-H line)
-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the following connectors.





-3. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The F_CAN-H wire is OK. Go to step 6.
-NO- Repair an open in the wire between the EPS control unit and the ECM/PCM.

6. Open wire check (F_CAN-L line):

Open wire check (F_CAN-L line)
-1. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- The F_CAN-L wire is OK. Go to step 8.
-NO- Repair an open in the wire between the EPS control unit and the ECM/PCM.

7. ECM/PCM check (update or substitution):

ECM/PCM check (update or substitution)
-1. Update the ECM/PCM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM/PCM: R18Z1 engine , K24Z7 engine Service and Repair.

-2. Turn the ignition switch to ON (II).

-3. Clear the DTC with the HDS.

-4. Turn the ignition switch to LOCK (0).

-5. Check for DTCs with the HDS.

Is DTC 21-01 or 21-02 indicated?
-YES- Replace the EPS control unit Service and Repair.
-NO- If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM: R18Z1 engine , K24Z7 engine Service and Repair.

8. EPS control unit check (update):

EPS control unit check (update)
-1. Reconnect the following connectors.





-2. Turn the ignition switch to ON (II).

-3. Update the EPS control unit Programming and Relearning if it does not have the latest software.

-4. Turn the ignition switch to LOCK (0).

-5. Raise and support the vehicle Service and Repair, and allow all wheels to rotate freely.

-6. Connect the HDS to the data link connector (DLC).

-7. Start the engine.

-8. Turn off the VSA function by using the VSA OFF switch.

-9. Run the vehicle while in 4th gear (M/T), or D (A/T).

-10. Check the VEHICLE SPEED in the EPS DATA LIST with the HDS.

Is the vehicle speed indicated?
-YES- Troubleshooting is complete.
-NO- Replace the EPS control unit Service and Repair.