C0235

CIRCUIT DESCRIPTION
The Electronic Brake Control Module (EBCM) receives the rear wheel speed signal from the Vehicle Control Module (VCM). The rear wheel speed signal originates from the Vehicle Speed Sensor (VSS) which is connected to the VCM. The vehicle speed sensor coil emits an electromagnetic field. A toothed ring in the transmission passes by the vehicle speed sensor and disrupts this electromagnetic field. The disruption in the field causes the vehicle speed sensor to produce a sinusoidal (AC) voltage signal. The frequency and amplitude of the sinusoidal (AC) voltage signal are proportional to the speed of the transmission output shaft. The amplitude of the vehicle speed signal is also directly related to the distance between the wheel speed sensor coil and the toothed ring. This distance is referred to as the air gap.

CONDITIONS FOR SETTING THE DTC
EBCM not seeing the correct voltage level from the VCM at start-up.

ACTION TAKEN WHEN THE DTC SETS
^ The ABS indicator lamp turns on
^ The ABS disables

DTC C0235 is a Condition Latched DTC, which indicates that the above actions are true until the condition is cleared. The DTC will not be stored in memory unless it occurs while the vehicle is travelling greater than 13 km/h (8 mph), and the brake pedal is pressed.

CONDITIONS FOR CLEARING THE DTC
^ Repair the conditions responsible for setting the DTC
^ Use the Scan Tool Clear DTCs function

DIAGNOSTIC AIDS
This DTC can be set by a faulty EBCM or a fault in CKT 1827.

If the voltage readings are low or varying, the battery or charging system could be the cause. Check these areas before replacing any components. In addition, any of the following conditions may cause an intermittent malfunction:
^ A poor connection
^ Wire insulation that is rubbed through
^ A wire breaks inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint 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 the steps in the diagnostic table:
2. This step uses the voltage output from the VCM to check the 1827 CKT.
3. This step checks the 1827 CKT for proper resistance.
5. This step checks for a short in the wiring between the ECBM and the VCM.