EBCM Self Test
The EBCM self test checks for proper operation of the entire ABS. The ABS indicator lamp, controlled by the EBCM and located in the instrument panel, alerts the driver of a malfunction with the ABS. The diagnostic status lamps (located on the side of the EBCM housing) assist the technician to locate a malfunction with a specific ABS component. Special tools or equipment are not needed in order to read the EBCM diagnostic status lamps.
| • | When the EBCM detects a malfunction with the ABS, the following actions occur: |
| - | The ABS indicator lamp is illuminated. |
| - | The associated diagnostic status lamps are illuminated. |
| - | All or a portion of the ABS is disabled (standard braking is available). |
| - | The portion of the ABS disabled is dependent upon the type of malfunction present. |
| • | If the air modulator at the right front wheel has an open circuit, the EBCM disables the ABS for BOTH the right front and left rear wheels (the EBCM divides and separates the brakes diagonally). |
| The ABS will continue to function for the left front wheel and right rear wheel. A low voltage problem or EBCM malfunction will result in complete disabling of the ABS. |
| Two or more failures will also result in the disabling of the entire system. With the failed component approach described above, the vehicle will retain improved braking stability after a single failure. |
| • | The failed condition is stored and not cleared by the loss of power to the EBCM. The diagnostic status lamps will illuminate when the power is restored and remain illuminated until the failure is corrected. |
| After the problem is corrected, the technician can clear or reset the EBCM diagnostics by passing a small magnet over the RESET point in the diagnostics window. |
EBCM Diagnostic Status Lamps
There are nine diagnostic status lamps located on the side of the EBCM. There is also a mechanically actuated reset switch. The first five diagnostic status lamps locate a problem to a specific component on the vehicle. The remaining four diagnostic status lamps indicate the location of the component. For normal operation, the only diagnostic status lamp illuminated will be the green VOLT diagnostic status lamp. If a malfunction exists with a component or component wiring, three diagnostic status lamps will be illuminated. For example, a malfunction with a right front wheel speed circuit would illuminate the RIGHT, FRONT and SENS diagnostic status lamps. The diagnostic status lamps are controlled by the EBCM and are either on or off depending upon their monitor function.
RESET
The EBCM contains a magnetically sensitive switch that is used to reset the EBCM. The reset switch is located directly beneath the RESET label on the EBCM. The device will respond to a magnet which has sufficient strength to lift a three (3) ounce weight. Holding a magnet against the RESET will cause all diagnostic status lamps to initially illuminate and erase malfunctions one at a time.
VOLT Diagnostic Status Lamp
The VOLT diagnostic status lamp is green and will be illuminated during vehicle operation in order to indicate that vehicle voltage is present at the EBCM. If vehicle voltage is below 11.0 V or above 17.0 V, the VOLT status lamp will flash.
ECU Diagnostic Status Lamp
The ECU diagnostic status lamp is red and will illuminate in order to indicate an EBCM malfunction. The ECU diagnostic status lamp is illuminated for all EBCM failures except low voltage. For voltages less than 9.0 V, the ECU diagnostic status lamp illuminates to indicate an inoperative controller. When the voltage exceeds 9.0 V, the ECU status lamp will no longer be illuminated.
SENS Diagnostic Status Lamp
The SENS diagnostic status lamp is red and will illuminate in order to indicate a malfunction with one of the four wheel speed sensor circuits. The SENS diagnostic status lamp will illuminate with the RIGHT or LEFT diagnostic status lamp and the FRONT or REAR diagnostic status lamp.
MOD Diagnostic Status Lamp
The MOD diagnostic status lamp is red and will illuminate in order to indicate a malfunction with one of the four modulator solenoid circuits. The MOD diagnostic status lamp will illuminate with the RIGHT or LEFT diagnostic status lamp and the FRONT or REAR diagnostic status lamp.
LEFT Diagnostic Status Lamp
The LEFT diagnostic status lamp is red and will illuminate in order to indicate the location of a malfunction. The LEFT diagnostic status lamp will illuminate with the FRONT or REAR diagnostic status lamp and the MOD or SENS diagnostic status lamp.
RIGHT Diagnostic Status Lamp
The RIGHT diagnostic status lamp is red and will illuminate in order to indicate the location of a malfunction. The RIGHT diagnostic status lamp will illuminate with the FRONT or RIGHT lamps and the MOD or SENS diagnostic status lamp.
REAR Diagnostic Status Lamp
The REAR diagnostic status lamp is red and will illuminate in order to indicate the location of a malfunction. The REAR diagnostic status lamp will illuminate with the RIGHT or LEFT diagnostic status lamp and the MOD or SENS diagnostic status lamp.
MID Diagnostic Status Lamp
The MID diagnostic status lamp is not used in troubleshooting the ABS and should illuminate only when a magnet is held on the RESET switch.
FRONT Diagnostic Status Lamp
The FRONT diagnostic status lamp is red and will illuminate in order to indicate the location of a malfunction. The FRONT diagnostic status lamp will illuminate with the RIGHT or LEFT diagnostic status lamp and the MOD or SENS diagnostic status lamp.
