For 1990-2009 cars

Table 1: | Visual Inspection

### Circuit Description

The EBCM/EBTCM diagnostic system check identifies problems associated with the EBCM/EBTCM. Use this system check as the starting point for any EBCM/EBTCM complaint. The check 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.

#### Visual Inspection

Item | Inspection | Corrective Action
--- | --- | ---
Parking Brake |

• | Full release.

• | Proper switch function. When necessary, unplug the switch connector to verify.

• | Operate manual release lever to verify release.

• | Adjust the cable or repair release system. Refer to Park Brake Cable Replacement in Park Brake.

• | Repair the switch.

Major Components:

• | Master Cylinder Fluid Reservoir

• | Brake Pressure Modulator Valve (BPMV)

• | Low fluid levels.

• | External leaks.

• | Proper assembly.

• | Determine the cause of the fluid loss and repair. Add fluid to the master cylinder reservoir. Refer to Master Cylinder Reservoir Filling in Hydraulic Brakes.

• | Repair leaks.

• | Install of position components properly.

• | IP Fuse Block:

- | ABS Fuse

- | IGN 1 Fuse (Buick)

- | CHIME Fuse (Oldsmobile)

• | RH Rear Fuse Block:

| HZRD/STOP Fuse

• | Engine Compartment Fuse Block:

- | ABS MAIN Fuse

- | ABS PUMP MOTOR Fuse

• | Open fuse.

• | Proper engagement.

Replace the fuse. Refer to Wiring Repairs in Wiring System.

• | Connectors:

- | ABS Main Relay

- | ABS Pump Motor Relay

- | BPMV Fluid Level Switch

- | Wheel Speed Sensors

- | Electronic Brake (and Traction) Control Module (EBCM/EBTCM)

- | Brake Pressure Modulator Valve (BPMV)

- | Master Cylinder Reservoir

- | Stoplamp/BTSI Switch

- | ABS/TCC Switch

- | C102

- | C103

- | C104

- | C401

• | Grounds:

- | G104

- | G106

- | G202

• | Proper engagement.

• | Loose or corroded wires.

• | Loose or corroded terminals.

• | Loosed, corroded, or broken eyelets

• | Properly engage connector.

• | Repair wire, terminal, or eyelet. Refer to Wiring Repairs in Wiring System.

### Diagnostic Aids

An intermittent failure in the electronic system may be very difficult to detect and accurately diagnose. The EBCM/EBTCM tests 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 may be the cause of most intermitting problems. When an intermitting condition is suspected, inspect the 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 condition may be intermittent. Perform the tests shown while moving the related wiring and connectors. This may often cause the malfunction to occur. Perform a thorough inspection of all of the related wiring and connectors pertaining to the history DTC stored. Refer to General Electrical Diagnosis in Wiring Systems.

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. Install 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 Communications System Check in Data Link Communications
3 |

1. With the scan tool in ABS/TCS Special Functions run the AUTOMATED test.
2. With the scan tool read ABS/TCS DTCs.

Are there any current Diagnostic Trouble Codes?

--

Go to Diagnostic Trouble Code (DTC) List for Applicable DTC Table

Go to Step 4

4 | Cycle the ignition switch from the OFF to RUN position, engine off. Does the ABS Indicator turn on then turn off after several seconds? | -- | Go to Step 5 | Go to Step 7
5 | Is this vehicle equipped with Traction Control? | -- | Go to Step 6 | Go to Step 11
6 | Cycle the ignition switch from the OFF to RUN position, engine off. Does the Traction Off Indicator turn on then turn off after several seconds? | -- | Go to Step 8 | Go to Step 9
7 | Does the ABS Indicator stay on? | -- | Go to ABS Indicator Always On | Go to ABS Indicator Inoperative
8 | Is the vehicle an Oldsmobile? | -- | Go to Step 10 | Go to Step 11
9 | Does the Traction Off Indicator stay on? | -- | Go to Traction Off Indicator Always On | Go to Traction Off Indicator Inoperative
10 | Cycle the ignition switch from the OFF to RUN position, engine Off. Does the Traction Active Indicator turn on then turn off after several seconds? | -- | Go to Step 11 | Go to Traction Active Indicator Not Operating Properly
11 | Are there any history DTCs? | -- | Go to Step 12 | System OK
12 |

1. Refer to the appropriate DTC table for the history DTC.
2. Read the diagnostic aids, and the conditions for setting the DTC.
3. Carefully drive the vehicle above 24 Km/h (15 mph) for several minutes, while monitoring a scan tool.

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

--

Go to Diagnostic Trouble Code (DTC) List for Applicable DTC Table

System OK