With 4 Wheel Disc Brakes

DTC C0027 Left Front Wheel Speed Signal Erratic (Part 1 Of 2):

DTC C0027 Left Front Wheel Speed Signal Erratic (Part 2 Of 2):

LF Wheel Speed Sensors Schematic:

CIRCUIT DESCRIPTION
As a toothed ring passes by the wheel speed sensor, changes in the electromagnetic field cause the wheel speed sensor to produce a sinusoidal (AC) voltage signal whose frequency and amplitude is proportional to wheel speed. The magnitude of this signal is directly related to wheel speed and the proximity of the wheel speed sensor to the toothed ring, often referred to as the air gap.

CONDITIONS FOR SETTING DIAGNOSTIC TROUBLE CODE (DTC)
^ Average wheel speed for all wheel speed signals is greater than 25mph.
^ Average left front wheel speed is greater than 25mph.
^ No output from left front wheel speed signal for 15ms. Anything which suddenly prevents (intermittant) the left front wheel speed signal to drop to 0 while the vehicle is moving greater than 25mph.

ACTION TAKEN WHEN THE DTC SETS
^ ANTILOCK indicator lamp is illuminated
^ ABS is disabled

NOTE: DTC C0027 is an Ignition Latched DTC which indicates the above is true until the ignition is fumed to OFF (even if the cause of the DTC is intermittent).

DIAGNOSTIC AIDS
An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.
Any circuitry that is suspected of causing the intermittent complaint should be thoroughly checked for backed out terminals, improper matting, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.
When inspecting a wheel speed sensor, inspect the sensor terminals and harness connector for corrosion. If evidence of corrosion exists, replace the wheel speed sensor.
Resistance of the wheel speed sensor will increase with an increase in sensor temperature. Refer to the following table for temperature/resistance values.

^ -40 to 4°C (-40 to 40°F)
@ 1089 to 1630 ohms

^ 5 to 43°C (41 to 110°F)
@ 1337 to 1900 ohms

^ 44 to 93°C (111 to 200°F)
@ 1560 to 2230 ohms

^ 94 to 150°C (201 to 302°F)
@ 1850 to 2651 ohms

DTC CHART TEST DESCRIPTION
The numbers below refer to the numbers on the diagnostic chart.
2. Check Electronic Brake Control Module (EBCM) 4-way connector for looseness, Corrosion, etc.
3. Measure the resistance of EBCM 4-way connector pins A and D.
4. Measure resistance at the left front wheel speed sensor connector.
5. Inspect the left front Wheel Speed Sensor (WSS) and tone wheel for physical damage or excessive clearance.