Teves Mk II
Only certain ABS malfunctions will cause the EBCM to store diagnostic trouble codes. Failures causing a code will generally involve wheel speed sensors, main valve or the inlet and outlet valves. Conditions affecting the pump/motor assembly, the accumulator, pressure switch or fluid level sensor usually do not cause a code to set.
The EBCM will store trouble codes in a non-volatile memory. These codes remain in memory until erased through use of the correct procedure. The codes are NOT erased by disconnecting the EBCM, disconnecting the battery cable or turning off the ignition. Always be sure to clear the codes from the memory after repairs are made. To read stored ABS trouble codes:
- Turn ignition switch to NO . Allow the pump to charge the accumulator; if fully discharged, dash warning lights may stay on up to 30 seconds. If ANTI-LOCK warning light does not go off within 30 seconds, note it and go to Step 2.
- Turn ignition switch to OFF .
- Remove the cover from the ALDL connector. Enter the diagnostic mode by using a jumper wire to connect pins H and A or to connect pin H to body ground. The ALDL is located on the driver's side of the vehicle under the dash.
- Turn the ignition switch to RUN and count the light flashes for the first digit of the first code. The ANTI-LOCK light should illuminate for 4 seconds before beginning to flash. If, after 4 seconds, the light turns off and stays off, no codes are stored.
- The light will pause for 3 seconds between the first and second digits of the first code and then continue flashing. When counting flashes, count only the ON pulses.
- When the EBCM is finished transmitting the second digit of the first code, the ANTI-LOCK light will remain on. This last, constant ON should not be counted as a flash. Record the 2-digit code.
- Without turning the ignition switch OFF , disconnect the jumper from pin H and reconnect it. If an additional code is present, it will be displayed in similar fashion to the first. Record the second code.
- Repeat the disconnection and reconnection of pin H without changing the ignition switch until no more codes are displayed. The system is capable of storing and displaying 7 codes; the ANTI-LOCK warning light will stay on continuously when all codes have been displayed.
- After recording all codes, remove the jumper from the ALDL and replace the cover.
Teves Mk IV
The EBCM monitors operating conditions for possible system malfunctions. Malfunctions are detected by comparing system conditions against standard operating limits. Evidence of a malfunction is stored in the computer memory in the form of a 2-digit numerical Diagnostic Trouble Code (DTC).
Trouble codes are accessed by connecting a bi-directional scan tool to the Assembly Line Diagnostic Link (ALDL) connector. Follow the scan tool manufacturer's instructions to read the trouble codes. After all codes have been read and repairs are completed, use the scan tool to clear the codes, then cycle the ignition switch.
`Current' or `history' codes are not differentiated in the EBCM, however, if the amber ANTILOCK lamp is illuminated before entering the diagnostic mode, at least one DTC is current. If the amber ANTILOCK lamp is not illuminated before entering the diagnostic mode, no DTC is current. If more than one DTC is stored and the amber ANTILOCK lamp was illuminated before entering the diagnostic mode, it is impossible to determine between current and history trouble codes.Bosch®
The EBCM/EBTCM can store several fault codes simultaneously. The order in which the codes are displayed may not indicate the order in which they occurred. If the ANTILOCK warning light is on before displaying the trouble codes, at least 1 of the codes is current, having occurred during the present ignition cycle.
If a scanning diagnostic tool is not available, the system may still be put in the diagnostic mode except when any of the current or hard faults involve the solenoid valves or pump motor. If one or more of the codes is/are Code 41, 45, 55, or 63, diagnostic display of the trouble codes cannot occur until the fault has been repaired. (Use of the scan tool eliminates this problem; all stored codes will display.)
To enter the diagnostic mode and have fault codes transmitted without the use of a scan tool:
- Turn ignition switch ON . If the ANTILOCK warning light does not go out within 4 seconds, make a note of it and continue.
- Turn ignition switch OFF . Remove the cover from the Assembly Line Diagnostic Link (ALDL) connector, located behind the left-hand side of the instrument panel, to the right of the parking brake.
- Connect a jumper wire between pin H of the ALDL connector and body ground or connect pin H to pin A.
- Turn the ignition switch ON and watch the ANTILOCK warning light. It should illuminate for 4 seconds and switch off, after which it will flash the stored codes.
- The first code displayed will be Code 12. This is an initialization code and is not a fault code. It will be displayed as one flash followed by 2 flashes and a pause. Code 12 will be displayed 3 times in succession before fault codes are displayed.
- Count the light flashes for any stored fault codes. Each stored code will be displayed 3 times before the next code is displayed. Record each code in writing. If no codes are stored, the readout of the Code 12 initialization sequence will begin again.
- The code readout will repeat until the ground or jumper at the ALDL is removed. After recording all stored codes, disconnect the jumper from the ALDL and reinstall the cover.
The codes must be retrieved using an OBD-II capatible scan tool linked through the 16-pin diagnostic connector under the instrument panel. Follow the scan tool manufacturer's instructions to retrieve the codes.
Teves Mk II
Stored ABS trouble codes should not be cleared until all repairs are completed. The control module will not allow any codes to be cleared until all have been read. Drive the vehicle at a speed greater than 18 mph to clear ABS trouble codes.
Re-read the system; if codes are still present, not all codes were read previously or additional repair is needed.Teves Mk IV
Use an appropriate scan tool to clear the trouble codes.Bosch®
The control module will not permit codes to be cleared until all have been read. Codes cannot be cleared by unplugging the module, disconnecting the battery or turning the ignition OFF .
If using the Tech I diagnostic tool, codes may be cleared using the Clear Codes function of the tool.
To clear codes via the ALDL connector:
- Turn the ignition switch OFF .
- Ground pin H on the ALDL connector.
- Turn the ignition switch ON .
- Wait for codes to begin flashing.
- Unground pin H for at least 1 second, then reconnect the ground. This must be done 3 times within 10 seconds.
- Wait at least 15 seconds. Repeat Steps 1-4 of this procedure: confirm that code 12 is the only code being flashed. If not, either codes were not cleared properly or an ABS fault still exists.
Additionally, if the vehicle ignition is cycled a pre-determined number of times without a particular fault reappearing, the related fault code will be erased from the control module memory and the ignition cycle counter will reset to zero. The reset threshold is usually either 50 or 100 cycles, depending on the model and the system fault.1997-98 Models
The codes must be cleared using an OBD-II capatible scan tool linked through the 16-pin diagnostic connector under the instrument panel.