C0237

Circuit Description
The EBCM receives the rear wheel speed signal from the VCM/PCM. The rear wheel speed signal originates from the Vehicle Speed Sensor (VSS) which is connected to the VCM/PCM.

Conditions for Running the DTC
^ The ignition switch is in the RUN position.
^ The vehicle speed is greater than 32 km/h (20 mph) with brake applied, or 20 km/h (12 mph) with brake released.

Conditions for Setting the DTC
The EBCM sees the rear speed signal line drop out for greater than 15 milliseconds and return.

Action Taken When the DTC Sets
^ The ABS indicator lamp turns on.
^ The ABS disables.
DTC C0237 initially sets as a condition latched code. This means that the ABS system will be disabled and the ABS indicator lamp remains on as long as the condition exists. If the erratic DTC is set 3 consecutive times during the same ignition cycle, the DTC will set as an ignition latched DTC. This means that the ABS system will be disabled and the ABS indicator lamp remains on until the ignition is turned off, even if the fault goes away.
DTC C0237 is a DRP critical DTC, which means that DRP is disabled and the BRAKE indicator lamp will also light.

Conditions for Clearing the DTC
^ Repair the conditions responsible for setting the DTC.
^ Use the Scan Tool Clear DTCs function.
^ Both a Condition Latched or Ignition Latched DTC may exist momentarily, or constantly. In either of the cases, the DTC will be stored in the EBCM memory until the DTC is repaired and/or cleared. After the DTC is repaired and/or cleared and the ignition switch is turned to the ON position, the ABS lamp will remain lit until the EBCM completes a power-up self test. This test concludes when the vehicle has reached a speed of greater than 13 km/h (8 mph) and the wheel speed inputs have been checked by the EBCM.

Diagnostic Aids
Check for and clear DTCs in the VCM/PCM first.
This DTC can be set by a malfunction in the 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 broken wire 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:
3. This step uses the voltage output from the PCM/VCM to check the 1827 CKT.
4. This step attempts to determine if there the VCM/PCM can process the VSS input and deliver a VSS output on CKT 1827.