For 1990-2009 cars

### 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

- | Dirty or corroded terminals

- | Damage to connector bodies

• | 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. Refer to Troubleshooting Procedures Cell 4 in Electrical Diagnosis.

#### ABS Diagnostic System Check

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 |

1. Reconnect all previously disconnected components.
2. Cycle the ignition switch from the OFF to RUN position, engine off.
3. Plug a scan tool into the Diagnostic Link Connector (DLC).

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 UART serial data line? | -- | Go to No Communication with Electronic Brake Control Module/Electronic Brake and Traction Control Module | Go to Data Link Cell 50 in Electrical Diagnosis
3 |

1. Unplug the scan tool from the DLC.
2. Cycle the ignition switch from the RUN to OFF to START position.
3. Carefully drive the vehicle above 24 Km/h (15 mph) for several minutes.
4. Leave the vehicle running and plug the scan tool into the DLC.
5. With the scan tool read ABS/TCS DTC(s)

Are there any current Diagnostic Trouble Codes?

--

Go to Applicable DTC Table

Go to Step 4

4 |

1. Remove the scan tool from the DLC.
2. Cycle the ignition switch from the RUN to OFF to RUN position, engine off.

Does the ABS Indicator turn on, then turn off after several seconds?

--

Go to Step 6

Go to Step 5

5 | Does the ABS Indicator stay on? | -- | Go to ABS Indicator Always On | Go to ABS Indicator Inoperative
6 | Cycle the ignition switch from the RUN to OFF to RUN position, engine off. Does the Low Traction Indicator turn on, then turn off after several seconds? | -- | Go to Step 8 | Go to Step 7
7 | Does the Low Traction Indicator stay on? | Go to Low Traction Indicator Always On | Go to Low Traction Indicator Inoperative
8 | Is this vehicle equipped with Traction Control? | -- | Go to Step 9 | Go to Step 14
9 | Is this vehicle a Chevrolet? | -- | Go to Step 10 | Go to Step 12
10 | Cycle the ignition switch from the RUN to OFF to RUN position, engine off. Does the ASR Indicator turn on, then turn off after several seconds? | -- | Go to Step 14 | Go to Step 11
11 | Does the ASR Indicator stay on? | -- | Go to Acceleration Slip Regulation Indicator Always On | Go to Acceleration Slip Regulation Indicator Inoperative
12 | Cycle the ignition switch from the RUN to OFF to RUN position, engine off. Does the TCS Off Indicator turn on, then turn off after several seconds? | -- | Go to Step 14 | Go to Step 13
13 | Does the TCS Off indicator stay on? | -- | Go to Traction Control System Off Indicator Always On | Go to Traction Control System Off Indicator Inoperative
14 | Are there any history DTC(s)? | -- | Go to Step 15 | System OK
15 |

1. Refer to the appropriate DTC table for the history DTC.
2. Read the diagnostic aids and conditions for setting the DTC.
3. Cycle the ignition switch from the OFF to RUN position.
4. Carefully drive the vehicle above 24 Km/h (15 mph) for several minutes.
5. Leave the vehicle running and plug the scan tool into the DLC.
6. With the scan tool read the ABS/TCS DTC(s).

Did the history DTC set as a current DTC while the vehicle was being driven?

--

Go to Applicable DTC Table

System OK