Circuit Description
The 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.
Conditions for Setting the DTC
| • | EBCM seeing the rear speed signal line drop out and return. This malfunction can be caused by a malfunction in the VSS, or a fault in CKT 821, 822 or 1827. |
| • | The EBCM attempts to detect an erratic rear speed signal every 5 milliseconds. If the rear speed signal is missing for greater than 15 milliseconds with a vehicle speed greater than 32 km/h (20 mph) with brake applied, or 20 km/h (12 mph) with brake released a DTC C0237 will set. At this point the DTC will be condition latched. This means that the ABS system will be disabled and the ABS indicator lamp stays 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 stays on until the ignition is turned off; even if the fault goes away. |
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 stays 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 stays 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 it is repaired, and/or the DTC is cleared. After the DTC is repaired and/or cleared and the ignition is turned to ON, 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
Using the Scan Tool, check for any powertrain DTCs. Resolve any powertrain DTCs before starting with this DTC table.
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 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:
-
This step uses the voltage output from the VCM to check the 1827 CKT.
-
This step checks the 1827 CKT for proper resistance.
-
This step checks for a short in the wiring between the ECBM and the VCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | |
Is the voltage measurement within the specified range? | Greater than 10 volts | Go to Step 4 | Go to Step 3 | |
Is the resistance measurement within the specified range? | 0-2ohms | Go to Step 5 | Go to Step 8 | |
4 |
Did the DTC set? | -- | Go to Step 6 | Go to Step 7 |
Using a J 39200 , measure the resistance from terminal E of the 10-way EBCM harness connector to ground. Is the resistance measurement within the specified range? | OL | Go to Step 9 | ||
6 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Is the repair complete? | -- | -- | |
7 | Malfunction is intermittent.
Refer to Diagnostic Aids for more information. Is the repair complete? | -- | -- | |
8 | Repair the open in CKT 1827. Is the repair complete? | -- | -- | |
9 | Repair short to ground in CKT 1827. Is the repair complete? | -- | -- |
