GM Service Manual Online
For 1990-2009 cars only

Object Number: 95919  Size: MF
ABS Components
ABS/TCS Schematics

Circuit Description

The EBTCM Diagnostic System Check is an organized approach to identify problems associated with the EBTCM. This check must be the starting point for any EBTCM complaint, and will direct you to the next logical step in diagnosing the complaint. The 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 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 Intermittents and Poor Connections

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 ON position, engine OFF.
  3. Plug a scan tool into the Diagnostic Link Connector (DLC),

Does the Scan Tool communicate with the EBTCM?

--

Go to Step 3

Go to Step 2

2

Does the scan tool communicate with the BCM?

--

Go to No Communication with EBTCM

Go to Data Link Communications System Check

3

  1. With the scan tool in ABS/TCS Special Functions run the AUTOMATED test.
  2. With the scan tool read ABS/TCS DTC(s).

Are there any current Diagnostic Trouble Codes?

--

Go to Applicable DTC Table in DTC Table

Go to Step 4

4

Cycle the ignition switch from the OFF to ON position.

Does the ABS Indicator come On then go Off after several seconds?

--

Go to Step 6

Go to Step 5

5

Does the ABS Indicator come On and stay On?

--

Go to ABS Indicator Always On

Go to ABS Indicator Inoperative

6

Cycle the ignition switch from the OFF to ON position.

Does the Traction Off Indicator (car icon) come On then go Off after several seconds?

--

Go to Step 9

Go to Step 7

7

Does the Traction Off Indicator (car icon) come On and stay On?

--

Go to Step 8

Go to Traction Off Indicator Inoperative

8

Press and release the Traction Control Switch.

Does the Traction Off Indicator (car icon) turn Off?

--

Go to Step 9

Go to Traction Off Indicator Always On

9

Are there any history DTC(s)?

--

Go to Step 10

System OK

10

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

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

--

Go to Applicable DTC Table in DTC Table

System OK