C0236

CIRCUIT DESCRIPTION
The Electronic Brake Control Module (EBCM) receives the rear wheel speed signal from the Vehicle Control Module (VCM) for gas engine vehicles or the Vehicle Speed Sensor Buffer for diesel engine vehicles. The rear wheel speed signal originates from the Vehicle Speed Sensor (Vehicle Speed Sensor (VSS)) which is connected to the VCM (gas) or the Vehicle Speed Sensor Buffer (diesel).

CONDITIONS FOR SETTING THE DTC
EBCM losing the rear wheel speed signal for at least 5 seconds while the vehicle is moving above 13 km/h (8 mph) with the brake pedal released.

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

DTC C0236 is an Ignition Latched DTC, which indicates that the above actions are true until the ignition is turned to OFF (even if the cause of the DTC is intermittent).

CONDITIONS FOR CLEARING THE DTC
^ Repair the conditions responsible for setting the DTC
^ Use the Scan Tool Clear Diagnostic Trouble Codes (DTCs) function

DIAGNOSTIC AIDS
This malfunction can be caused by a malfunction in the EBCM, VCM (gas) Vehicle Speed Sensor Buffer (diesel), VSS or a fault in CKT 821, 822 or 1827.

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

If the customer says that the ABS indicator lamp is on only during humid conditions such as rain, snow, or vehicle wash, then thoroughly inspect the suspected circuits for signs of water intrusion. Use the following procedure:
1. Spray the suspected area with a 5% salt water solution (two teaspoons of salt to 12 oz. of water)
2. Drive the vehicle above 24 km/h (15 mph) for at least 30 seconds.

If the DTC returns, replace the suspected harness.

TEST DESCRIPTION
The numbers below refer to the steps in the diagnostic table:
2. This step uses the voltage output from the VCM (gas) or Vehicle Speed Sensor Buffer (diesel) 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.