Circuit Description
The EBCM/EBTCM Diagnostic System Check is an organized approach to identify problems associated with the EBCM/EBTCM. This check must be the starting point for any EBCM/EBTCM complaint, and will direct you to the next logical step in diagnosing the complaint. The EBCM/EBTCM is a very reliable component and is not likely the cause of the malfunction. Most system complaints are linked to faulty wiring, connectors, and occasionally to components. Understanding the ABS system and using the tables correctly will reduce diagnostic time and prevent unnecessary parts replacement.
Diagnostic Aids
An intermittent failure in the electronic system may be very difficult to detect and to accurately diagnose. The EBCM/EBTCM test for different malfunctions under different vehicle conditions. For this reason, a thorough test drive is often needed in order to repeat a malfunction. If the system malfunction is not repeated during the test drive, a good description of the complaint may be very useful in locating an intermittent malfunction. Faulty electrical connections or wiring causes most intermitting problems. When an intermitting condition is suspected, check the suspected circuits for the following conditions:
| • | Poor mating of connector halves or backed out terminals |
| • | Improperly formed or damaged terminals |
| • | Wire chafing |
| • | Poor wire to terminal connections |
| • | Damage to connector bodies |
Important: Any battery disconnect or removal of battery positive voltage from the EBCM/EBTCM will set a DTC C1255 as a history code. Ignore this DTC. Immediately clear this DTC.
If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. Perform a thorough inspection of all related wiring and connectors pertaining to the history DTC stored.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Does the scan tool communicate with the EBCM/EBTCM? | -- | Go to Step 3 | Go to Step 2 |
2 | Does the scan tool communicate with other modules on the class 2 line? | -- | Go to No Communication with Electronic Brake Control Module/Electronic Brake and Traction Control Module | Go to Data Link Communications System Check in Wiring Systems |
3 |
Are any DTCs present? | -- | Go to the applicable DTC table | Go to Step 4 |
4 | Cycle the ignition from the OFF to the RUN position with the engine off. Does the ABS indicator turn On then Off? | -- | Go to Step 6 | Go to Step 5 |
5 | Does the ABS indicator stay on? | -- | Go to ABS Indicator Always On | |
6 | Is the vehicle TCS equipped? | -- | ||
7 | Cycle the ignition from the OFF to the RUN position with the engine off. Does the Traction Off indicator turn On then Off? | -- | Go to Step 7 | |
8 | Does the Traction Off indicator stay on? | -- | ||
9 | Are there any history DTCs? | -- | Go to Step 10 | System OK |
10 |
Does the history DTC set as a current DTC while the vehicle is being driven? | -- | Go to the applicable DTC table | System OK |
