Code No. C1222:
Wheel SPD.SNSR.power circuit
Code No. C1225: Deviation between wheel speed
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- 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 - Troubleshooting
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- Whenever ECU is replaced, ensure that the CAN bus lines are normal.
- When the hydraulic unit assembly (integrated with ASTC-ECU) is replaced, always
carry out the calibration of the steering wheel sensor and the G sensor (Refer to ).
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OPERATION
- A toothed rotor (for wheel speed detection) generates
a voltage pulse as it moves across the pickup field of each wheel speed sensor.
- The wheel speed sensor transmit the frequency of the pulses to the ASTC-ECU.
DIAGNOSIS CODE SET CONDITIONS
The ASTC-ECU monitors the signals from each wheel speed sensor. If any faults below is
found in these sensor signals, the ECU will set the relevant diagnosis code. When the abnormal
wheel is identified, diagnosis code No. C1201, C1206, C1211, or C1216 is set.
- Missing sensor signal
- Sensor signal, which will not be created under normal operation
- Unfeasible difference among the wheel speed sensor signals
- When the ABS/ASTC control is being activated for one minute or more.
PROBABLE CAUSES
Current trouble
- Improper installation of the wheel speed sensor
- Malfunction of the wheel speed sensor
- Wheel bearing malfunction
- Excessive gap between the wheel speed sensor and the rotor (for wheel speed detection)
- Adhesion of foreign materials on the rotor (for wheel speed detection)
- Deformation of the rotor (for wheel speed detection)
- Damaged harness wires and connectors
- Malfunction of the hydraulic unit assembly (integrated with ASTC-ECU)
Past trouble
- The following conditions may occur.
- Either of the right or left wheel is turning, or either of the front or rear
wheel are turning.
- Unstable vehicle attitude
- External noise interference
- The vehicle is driven on snowy or rough road.
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STEP 1. M.U.T.-III CAN bus diagnosis
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Use the M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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 Go to Step 3.
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 Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
On completion, go to Step 2.
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STEP 2. Diagnosis code recheck after resetting CAN bus lines
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Q.
Is the relevant diagnosis code No. C1222 or C1225 set?
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Go to Step 3.
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This diagnosis is complete.
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STEP 3. Check whether the wheel speed sensors are installed properly.
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Check the mounting status of wheel speed sensors (sensor dislocation, mounting bolt loosening,
etc.) for all wheels.
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Q.
Is the check result normal?
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Go to Step 4.
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Install the wheel speed sensor properly (Refer to ).
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STEP 4. Check the wheel speed sensor.
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Refer to .
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Q.
Is the check result normal?
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Go to Step 5.
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Replace the wheel speed sensor.
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STEP 5. Check for wheel bearing looseness
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| note |
The wheel bearing looseness is suspected to be the cause of excessive gap between the
wheel speed sensor and rotor. Therefore, check the wheel bearing looseness of each wheel.
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- Front: Refer to GROUP 26 - On-vehicle Service .
- Rear: Refer to GROUP 27 - On-vehicle Service .
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Q.
Is the check result normal?
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Go to Step 6.
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NO <when the relevant wheel is front> : Replace the wheel bearing (Refer to GROUP 26 - Front Axle Hub Assembly ).
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NO <when the relevant wheel is rear> : Replace the wheel bearing (Refer to GROUP 27 - Axle Shaft Assembly ).
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STEP 6. Check of the rotor (for wheel speed detection)
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Check the rotor (for wheel speed detection) for adhesion of foreign materials or deformation.
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Q.
Is the check result normal?
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Go to Step 7.
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NO <when the relevant wheel is front> : Remove the foreign materials and clean the rotor. If deformation is found, replace
the wheel bearing (Refer to GROUP 26 - Front Axle Hub Assembly ).
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NO <when the relevant wheel is rear> : Remove the foreign materials and clean the rotor. If deformation is found, replace
the wheel bearing (Refer to GROUP 27 - Axle Shaft Assembly ).
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STEP 7. Measure the voltage at the ASTC-ECU connector.
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(1)Connector check: ASTC-ECU connector and wheel speed sensor connectors
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(2)Disconnect the connector, and measure at the wiring harness side.
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(4)Measure the voltage between the power supply terminal as well as signal terminal
of wheel speed sensor circuit and the body earth.
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Position of wheel speed sensors
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Checking terminal
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Power supply terminal
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Signal terminal
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Right front wheel
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FR+
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FR-
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Left front wheel
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FL+
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FL-
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Right rear wheel
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RR+
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RR-
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Left rear wheel
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RL+
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RL-
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OK: 1 V or less
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Q.
Is the check result normal?
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Go to Step 8.
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NO (FR+ or FR- NG) : Go to Step 10.
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NO (FL+ or FL- NG) : Go to Step 11.
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NO (RR+ or RR- NG) : Go to Step 12.
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NO (RL+ or RL- NG) : Go to Step 13.
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STEP 8. Measure the resistance at the ASTC-ECU connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Measure the resistance between the power supply terminal as well as signal terminal
of each wheel speed sensor circuit and body earth.
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Position of wheel speed sensors
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Checking terminal
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Power supply terminal
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Signal terminal
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Right front wheel
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FR+
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FR-
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Left front wheel
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FL+
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FL-
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Right rear wheel
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RR+
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RR-
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Left rear wheel
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RL+
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RL-
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OK: No continuity
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Q.
Is the check result normal?
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Go to Step 9.
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NO (FR+ or FR- NG) : Go to Step 10.
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NO (FL+ or FL- NG) : Go to Step 11.
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NO (RR+ or RR- NG) : Go to Step 12.
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NO (RL+ or RL- NG) : Go to Step 13.
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STEP 9. Measure the voltage at the ASTC-ECU connector.
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(1)Measure with the connector(s) connected.
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(3)Measure the voltage between the power supply terminal as well as signal terminal
of each wheel speed sensor circuit and body earth.
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Position of wheel speed sensors
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Checking terminal
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Power supply terminal
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Signal terminal
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Right front wheel
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FR+
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FR-
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Left front wheel
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FL+
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FL-
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Right rear wheel
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RR+
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RR-
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Left rear wheel
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RL+
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RL-
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OK:
Power supply terminal: Approx. system voltage
Signal terminal: approximately 0.4 to 1.3 V
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Q.
Is the check result normal?
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Go to Step 14.
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NO (FR+ or FR- NG) : Go to Step 10.
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NO (FL+ or FL- NG) : Go to Step 11.
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NO (RR+ or RR- NG) : Go to Step 12.
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NO (RL+ or RL- NG) : Go to Step 13.
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STEP 10. Check the wiring harness wires between the ASTC-ECU connector
FR (+) or FR (-) terminal and the front wheel speed sensor (RH) connector
terminal.
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Check the front wheel speed sensor (RH) circuit for short and open.
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Q.
Is the check result normal?
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Go to Step 14.
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Repair the connector(s) and wiring harness.
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STEP 11. Check the wiring harness wires between the ASTC-ECU connector
FL (+) or FL (-) terminal and the front wheel speed sensor (LH) connector
terminal.
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Check the front wheel speed sensor (LH) circuit for short and open.
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Q.
Is the check result normal?
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Go to Step 14.
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Repair the connector(s) and wiring harness.
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STEP 12. Check the wiring harness wires between the ASTC-ECU connector
RR (+) or RR (-) terminal and the rear wheel speed sensor (RH) connector terminal.
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Check the rear wheel speed sensor (RH) circuit for short and open.
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Q.
Is the check result normal?
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Go to Step 14.
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Repair the connector(s) and wiring harness.
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STEP 13. Check the wiring harness wires between ASTC-ECU connector
RL (+) or RL (-) terminal and the rear wheel speed sensor (LH) connector terminal.
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Check the rear wheel speed sensor (LH) circuit for short and open.
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Q.
Is the check result normal?
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Go to Step 14.
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Repair the connector(s) and wiring harness.
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STEP 14. Diagnosis code recheck
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Check again if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Ignition switch: LOCK (OFF) position to ON
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(3)Drive the vehicle until the vehicles speed reaches 20 km/h.
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Q.
Is diagnosis code No. C1222 or C1225 set?
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Replace the wheel speed sensor (Refer to ).
Then go to Step 15.
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The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to Cope with Intermittent Malfunction ).
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STEP 15. Diagnosis code recheck
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Check again if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Ignition switch: LOCK (OFF) position to ON
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(3)Drive the vehicle until the vehicles speed reaches 20 km/h.
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Q.
Is diagnosis code No. C1222 or C1225 set?
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Replace the hydraulic unit assembly (integrated with ASTC-ECU) (Refer to ).
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This diagnosis is complete.
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