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:
Before you troubleshoot, record all freeze data and any on-board snapshot, and review the how to troubleshoot the EPS.
Troubleshoot any PGM-FI system DTCs first.
After completing repairs, do an All DTC check, and clear any related DTCs in other systems.

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

1.
EPS system check:

EPS system check
?1.
Raise and support the vehicle, and allow all wheels to rotate freely.

?2.
Start the engine.

?3.
Turn off the VSA function by using the VSA OFF switch.

?4.
Run the vehicle while in the 4th gear (M/T), or the D position (A/T, CVT).

?5.
Check the parameter(s) below with the HDS.
Signal
Current conditions
Values
Unit
VEHICLE SPEED
    

Is the vehicle speed indicated?

     
YES
     
     
     
Intermittent failure, the system is OK at this time.?
     
NO
     
     
     
Go to step 2.
2.
DTC check:

DTC check
?1.
Check for Pending or Confirmed DTCs with the HDS.
DTC Description
Confirmed DTC
Pending DTC
Freeze Frame
P0720 C-SHAFT SPD S MALFUNCTION
      
P0721 Output Shaft (Countershaft) Speed Sensor (Range/Performance)
      

Is DTC P0720 or P0721 indicated?

     
YES
     
     
     
Go to the indicated DTC's troubleshooting.?
     
NO
     
     
     
Go to step 3.
3.
Gauge control module operation check:

Gauge control module operation check
?1.
Check the tachometer and speedometer.

Is the tachometer and speedometer working correctly?

     
YES
     
     
     
Go to step 5.
     
NO
     
     
     
Go to step 4.
4.
Body electrical system DTC check:

Body electrical system DTC check
?1.
Check for DTCs in the gauge control module with the HDS.
DTC Description
DTC
Freeze Frame
     

Is DTC indicated?

     
YES
     
     
     
Go to the indicated DTC's troubleshooting.?
     
NO
     
     
     
Go to step 6.
5.
Open wire check (F CAN-H, F CAN-L lines):

Open wire check (F CAN-H, F CAN-L lines)
?1.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.

?2.
Short the SCS line with the HDS.


?3.
Disconnect the following connectors.

?4.
Check for continuity between test points 1 and 2.
Test condition
IG LOCK (0) or OFF mode
 
EPS control unit connector A (11P): disconnected
 
PCM connector A (51P): disconnected
Test circuit
F CAN-H
Test point 1
EPS control unit connector A (11P) No. 10 (WHT)
Test point 2
L4 engine: PCM connector A (51P) No. 2 (WHT)
V6 engine: PCM connector A (51P) No. 9 (WHT)

Test circuit
F CAN-L
Test point 1
EPS control unit connector A (11P) No. 11 (RED)
Test point 2
L4 engine: PCM connector A (51P) No.1 (RED)
V6 engine: PCM connector A (51P) No.10 (RED)
L4 engine

V6 engine


Is there continuity?

     
YES
     
     
     
The F CAN-H and F CAN-L wires are OK. Go to step 7.
     
NO
     
     
     
Repair an open in the wire between the EPS control unit and the PCM.?
6.
PCM check (update or substitution):

PCM check (update or substitution)
?1.
Update the PCM if it does not have the latest software, or substitute a known-good PCM.

?2.
Clear the DTC with the HDS.


?3.
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode, then start the engine.

?4.
Check for DTCs with the HDS.
DTC Description
DTC
Freeze Frame
21-01 Excessive Change of the Vehicle Speed Signal
    
21-02 Comparison between the Vehicle Speed and the Engine Speed Signal
    

Is DTC 21-01 or 21-02 indicated?

     
YES
     
     
     
Go to step 7.
     
NO
     
     
     
If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM.?
7.
EPS control unit check (update):

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

?2.
Update the EPS control unit if it does not have the latest software.

?3.
Raise and support the vehicle, and allow all wheels to rotate freely.

?4.
Start the engine.

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

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

?7.
Check for DTCs with the HDS.
DTC Description
DTC
Freeze Frame
21-01 Excessive Change of the Vehicle Speed Signal
    
21-02 Comparison between the Vehicle Speed and the Engine Speed Signal
    

Is DTC 21-01 or 21-02 indicated?

     
YES
     
     
     
     
NO
     
     
     
Troubleshooting is complete.?