Code No. C1044 Abnormality in periodical signal for RR wheel speed sensor



caution If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Prior to this diagnosis, diagnose the CAN bus lines (Refer to GROUP 54C, Trouble code diagnosis ).

OPERATION



  • The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
  • The pulse signals, which the wheel speed sensor creates, are sent to ABS-ECU. ABS-ECU uses the frequency of the pulse signals to determine the wheel speed.

DIAGNOSIS CODE SET CONDITIONS


ABS-ECU monitors the signals from each wheel speed sensor while the vehicle is being driven. If any periodical drop is found in these sensor signals, ABS-ECU will set the relevant diagnosis code.

PROBABLE CAUSES



  • Wheel bearing malfunction
  • Deformation of the magnetic encoder for wheel speed detection
  • Missing teeth of the magnetic encoder for wheel speed detection
  • Adhesion of foreign materials on the magnetic encoder for wheel speed detection
  • ABS-ECU malfunction
  • Disturbance of magnetization pattern for magnetic encoder for wheel speed detection

DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III CAN bus diagnosis


Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?

Go to Step 3.
Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnosis table ). On completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting CAN bus lines


Q. Is the diagnosis code No. C1044 set?

Go to Step 3.
This diagnosis is complete.

STEP 3. Check for wheel bearing looseness


note
  • Loose wheel bearing may increase the gap between the wheel speed sensor and the wheel speed detection magnet encoder.
  • Check the Rear wheel hub assembly <RR (2WD)> (Refer to GROUP 27A - On-vehicle Service ).
  • Check the wheel bearing <RR (4WD)> for looseness (Refer to GROUP 27B - On-vehicle Service ).

Q. Is the check result normal?

Go to Step 4.
NO (2WD) : Replace the rear wheel hub assembly (Refer to GROUP 27A - Rear axle hub assembly ).
NO (4WD) : Replace the wheel bearing (Refer to GROUP 27B - Rear axle hub assembly ).

STEP 4. Check of wheel speed detection encoder



Check the encoder for adhesion of foreign materials or deformation.

Q. Is the check result normal?

Go to Step 5.

NO (Presence of foreign materials) : Remove the foreign materials and clean the encoder so as not to disturb the magnetisation pattern on it while taking care of the magnet, magnetic substance, and magnetic attraction. When the encoder is deformed, replace the rear hub assembly.

NO <Deformation (2WD)> : Replace the rear wheel hub assembly (Refer to GROUP 27A - Rear axle hub assembly ).

NO <Deformation (4WD)> : Replace the wheel bearing (Refer to GROUP 27B - Rear axle hub assembly ).

STEP 5. Check whether the diagnosis code is reset.


(1)Erase the diagnosis code.
(2)Drive the vehicle at 20 km/h or more.
note The ABS warning lamp does not turn OFF in some cases unless the vehicle runs at 20 km/h or higher.

Q. Is the diagnosis code No. C1044 set?

Replace the ABS-ECU (Refer to ).
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).