Circuit Description
The wheel speed sensor creates an AC voltage as each wheel turns. The frequency of this voltage is proportional to the wheel speed.
The voltage is magnetically induced. The voltage is caused by a toothed sensor ring (mounted on the drive axle) which passes the stationary pickup coil of the wheel speed sensor.
The EBCM/EBTCM uses the wheel speed sensor signal in order to calculate the following values:
| • | The vehicle reference speeds |
| • | The speed of each wheel |
| • | The acceleration |
| • | The slip values |
Use these values in order to determine when the antilock or the traction control (when equipped) is required.
Conditions for Setting the DTC
The DTC C1222 sets when the EBCM/EBTCM detects electromagnetic interference (noise) in a wheel speed sensor signal.
The following components may be sources of interference:
| • | The accessory motors |
| • | The wiper motors |
| • | The ignition circuits |
| • | Any add-on or after market equipment |
The DTC C1222 also sets when the EBCM/EBTCM determines that a wheel speed signal is erratic. (An example of an erratic signal is a signal which indicates that a wheel is accelerating faster than physically possible.)
An intermittent or a short to ground in a wheel speed sensor may also cause the EBCM/EBTCM to set a DTC.
Action Taken When the DTC Sets
The following actions may be taken when the DTC sets:
| • | A malfunction DTC is stored |
| • | The ABS is disabled |
| • | The ANTILOCK indicator lamp is turned ON |
Conditions for Clearing the DTC
The DTC will be cleared under following conditions:
| • | Conditions for the malfunction are no longer present. Use the scan tool clear DTCs function. |
| • | 100 ignition switch key cycles have passed with no malfunctions detected |
Diagnostic Aids
One of the following condition may cause an intermittent malfunction:
| • | A poor connection |
| • | A rubbed through wire insulation |
| • | A wire that is broken inside the insulation |
Inspect any suspect circuitry for the following conditions:
| • | Backed out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | Poor terminal to wiring connections |
| • | Physical damage to the wiring harness |
Test Description
The numbers below refer to step numbers on the diagnostic table:
-
This step ensures that the sensor is capable of putting out the necessary voltage to the EBCM/EBTCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the ABS Diagnostic System Check performed? | -- | Go to Step 2 | |
2 |
Does the sensor or the wiring have any physical damage? | -- | Go to Step 7 | Go to Step 3 |
3 |
Is the resistance within the specified range? | 850-1350 ohms | Go to Step 4 | Go to Step 8 |
Is the AC voltage greater than the specified value? | 100 mV | Go to Step 5 | Go to Step 8 | |
5 |
| OL (Infinite) | Go to Step 6 | Go to Step 9 |
6 |
Does the DTC reset? | -- | Go to Step 10 | |
7 |
Does the DTC reset? | -- | Go to Step 3 | |
8 | Replace the RH front wheel speed sensor. Refer to Front Wheel Bearing and Hub Replacement in Front Suspension. Is the repair complete? | -- | Go to Step 11 | -- |
9 | Repair the short between CKT 833 and CKT 872. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 11 | -- |
10 | Replace the EBCM/EBTCM. Refer to Electronic Brake and Traction Control Module Replacement . Is the repair complete? | -- | Go to Step 11 | -- |
11 | Test drive the vehicle above 24 km/h (15 mph) for at least 30 seconds while monitoring the Scan Tool for ABS/TCS DTCs. Does the DTC reset? | -- | Go to Step 2 |
