[ Model - ECLIPSE CROSS / Year - 2018 ]
2018 / ECLIPSE CROSS / EC - Workshop Manual
17 -ENGINE AND EMISSION CONTROL > ADAPTIVE CRUISE CONTROL SYSTEM (ACC) > DIAGNOSIS CODE PROCEDURES > CODE NO. C1791: VEHICLE SPEED SIGNAL (INVALID)
Code No. C1791: Vehicle Speed Signal (Invalid)
 
 
cautionWhen the ACC/FCM-ECU is replaced, calibrate the radar (refer to ).
 
 
OPERATION
The ACC/FCM-ECU receives vehicle speed signal from the ASC-ECU.
 
 
DIAGNOSIS CODE SET CONDITION
Check Conditions
  • More than 2 seconds have passed since the ignition switch was turned to "ON" position.
  • ACC/FCM-ECU power voltage is more than 9 V and is less than 18 V.
Judgement Criterion
  • An invalid vehicle speed signal received from the ASC-ECU.
noteA diagnosis code is not set as a historic fault.
 
 
PROBABLE CAUSES
  • ASC system fault (front/rear wheel speed sensor fault)
  • Malfunction of the ACC/FCM-ECU
 
 
DIAGNOSIS PROCEDURE
STEP 1. Check the ASC system diagnosis code.
Using M.U.T.-IIISE, perform ASC system diagnosis code (Refer to GROUP 35C - Troubleshooting, Diagnosis Function ).
Is any diagnosis code set?
Repair the ASC system (Refer to GROUP 35C - Troubleshooting, Diagnosis Code Chart ).
Go to Step 2.
 
STEP 2. Check whether the diagnosis code is set again.
Check again if the diagnosis code is set in the ACC/FCM-ECU.
(1) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(2) Press the ACC ON/OFF switch to turn the ACC system to ON.
(3) On completion, check that the diagnosis code is set again.
Is diagnosis code No. C1791 set?
Replace the ACC/FCM-ECU (Refer to ).
It can be assumed that this malfunction is intermittent (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points, How to Cope with Intermittent Malfunction ).