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DTC C121C Torque request signal denied
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ).
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
OPERATION
ASC-ECU sends the signal to the PHEV-ECU as necessary to decrease the engine output for the ASC system operation.
 
 
 
DTC SET CONDITIONS
This DTC is set when the request for the decrease of output is rejected by the PHEV-ECU.
 
 
 
TROUBLESHOOTING HINTS
  • Wrong coding of PHEV-ECU
  • PHEV-ECU malfunction
  • ASC-ECU malfunction
  • External noise interference
 
 
 
 
DIAGNOSIS
STEP 1. Scan tool (M.U.T.-IIISE) CAN bus diagnostics.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect the Scan Tool (M.U.T.-IIISE) ."
(2) Turn on the power supply mode of the electric motor switch.
(3) Diagnose the CAN bus line.
(4) Turn off the power supply mode of the electric motor switch.
Is the check result normal?
Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). On completion, go to Step 2.
 
STEP 2. DTC recheck after resetting CAN bus lines.
Is DTC No.C121C set?
Go to Step 3.
This diagnosis is complete.
 
STEP 3. Scan tool (M.U.T.-IIISE) other system DTC.
Use scan tool (M.U.T.-IIISE) to check that the DTC is set in the PHEV-ECU.
Is the DTC set?
Troubleshoot the PHEV-ECU DTC (Refer to GROUP 54Da - PHEV-ECU, Troubleshooting ).
Go to Step 4.
 
STEP 4. Scan tool (M.U.T.-IIISE) DTC.
Check that DTC No.C1707 is set in ASC-ECU.
Is DTC No.C1707 set?
Troubleshoot for DTC No.C1707 (Refer to ).
Go to Step 5.
 
STEP 5. Scan tool (M.U.T.-IIISE) data list.
Check the following service data (Refer to ).
  • Item No. 68: Allow ESP torque request
Is the check result normal?
Go to Step 6.
Replace the PHEV-ECU (Refer to GROUP 54Da - PHEV-ECU )
 
STEP 6. Check whether the DTC is set again.
Erase the DTC.
Is DTC No.C121C set?
Replace the hydraulic unit (integrated with ASC-ECU) (Refer to ).
If the trouble symptom is resolved, an intermittent malfunction such as poorly engaged connector(s) or wiring harness is suspected (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).