GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1998 🢒 Century 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Diagnostic System Check

Object Number: 247834 Size: MF

System Description

The diagnostic system check is an organized method of identifying any problems caused by a malfunction in either of the following systems:

    • The Antilock Brake System (ABS)
    • The Enhanced Traction Control System (ETS)
    • The Traction Control System (TCS)

The service technician must begin diagnosis of any ABS or ABS/TCS complaint with the diagnostic system check.

The diagnostic system check directs the service technician to the next logical step in diagnosing the complaint.

The EBCM/EBTCM exchanges serial data through the connector C1 terminal A.

Connector C1 terminal A9 supplies the switched ignition voltage to the EBCM/EBTCM.

Connector C1 terminal B12 supplies the battery voltage to the EBCM/EBTCM.

Connector C2 terminal C supplies the switched battery voltage to the EBCM/EBTCM.

Connector C2 Terminal D provides the ground for the EBCM/EBTCM.

Diagnostic Process

Use the following ordered procedure when servicing the ABS/ETS/TCS.

Failure to use the following procedure may cause the loss of important diagnostic data. Failure to use the following procedure may lead to difficult and time-consuming diagnosis procedures.

  1. Use the following procedure to perform a vehicle preliminary diagnosis inspection:
    2. • Inspect the brake master cylinder fluid reservoir:
       - Verify that the brake fluid level is correct.
       - Inspect the master cylinder for contamination.
    • Inspect the brake modulator for the following conditions:
       - Leaks
       - Wiring damage
    • Inspect the brake components of all four wheels:
       - Verify that no drag exists.
       - Verify that the brake apply operation is correct.
    • Inspect for worn or damaged wheel bearings.
    • Worn or damaged wheel bearings may cause a wheel to "wobble".
    • Inspect the wheel speed sensors and the wheel speed sensor wirings:
       - Verify that all of the sensors solidly attach.
       - Inspect for wiring damage, especially at vehicle attachment points.
    • Inspect the outer CV joint:
       - Verify that the outer CV joint is aligned correctly.
       - Verify that the outer CV joint operates correctly.
    • Inspect the tires. Verify that the tires meet legal trend depth requirements.
  2. Perform the Diagnostic System Check.

    3. If any DTCs are displayed, select DTC History.

    2.1. Determine which malfunction occurred the most recently.
    2.2. Diagnose and repair the most recent malfunction first.
  3. Determine if the following conditions exist:
    4. • No DTCs are present.
    • There are malfunctions in the mechanical components.
    • The failure is intermittent and cannot be reproduced.
  4. If the above conditions exist, attempt to reproduce the malfunction:
    5. 4.1. Use the automatic snapshot feature of the Scan Tool while test driving the vehicle.

    Perform normal acceleration, stopping, and turning maneuvers during the test drive.

    4.2. If the test drive does not reproduce the malfunction, perform an ABS stop:
           - Perform the stop on a low coefficient surface (such as gravel).
           - Perform the stop from a speed of 48-80 km/h (30-50 mph).
           - Trigger the snapshot mode on any ABS/ETS/TCS DTC while performing the stop.
    4.3. If the ABS stop does not reproduce the malfunction, use the enhanced diagnostic information in the DTC History in order to determine if further diagnosis is needed. This determination will be based on the frequency of failure.
  5. Clear the ABS/ETS/TCS DTCs after all of the system malfunctions have been corrected.

Diagnostic Aids

Communication with the EBCM/EBTCM is not possible when excessive resistance exists in the following components:

    • The ground
    • The power supply circuits

If communication with the EBCM/EBTCM is not possible, perform the following actions:

    • Verify that the EBCM/EBTCM ground connection is good.
    • Verify that no excessive resistance exists in any of the power supply circuits.

Important: Zero the J 39200 test leads before making any resistance measurements. Refer to the J 39200 user's manual.

Step

Action

Value(s)

Yes

No

1
  1. Verify that the 24-way EBCM/EBTCM connector C1 is properly connected.
  2. Verify that the 8-way EBCM/EBTCM connector C2 is properly connected.
  3. Verify that the 8-way EBCM/EBTCM connector C3 is properly connected.
  4. Install a Scan Tool.
  5. Turn the ignition switch to the RUN position.

    6. Do not start the engine.

  6. Select the ABS portion of the chassis application on the Scan Tool.
  7. Select Data List on the Scan Tool.

Is data being received from the EBCM/EBTCM?

--

Go to Step 15

Go to Step 2

2

Read the Scan Tool display.

Does the Scan Tool display the message "No Communication With Vehicle"?

--

Go to Data Link Connector, Cell 50 in Electrical Diagnosis

Go to Step 3

3

Verify the correct connection of the Scan Tool to the DLC.

Is connection of the Scan Tool to the DLC correct?

--

Go to Step 4

Go to Step 30

4
  1. Turn the ignition switch to the OFF position.
  2. Remove the fuse block ABS - BCM Fuse (10A).
  3. Use the J 39200 in order to measure the resistance between the fuse block ABS - BCM Fuse (10A) terminals.

Is the resistance within the specified range?

0-2 ohms

Go to Step 5

Go to Step 22

5
  1. Install the fuse block ABS - BCM Fuse (10A).
  2. Remove the fuse block ABS Fuse (10A).
  3. Use the J 39200 in order to measure the resistance between the terminals of the fuse block ABS/ETC/TCS Fuse (10A).

Is the resistance within the specified range?

0-2 ohms

Go to Step 6

Go to Step 25

6
  1. Install the fuse block ABS Fuse (10A).
  2. Disconnect the 8-way EBCM/EBTCM connector C2.
  3. Use the J 39200 in order to measure the resistance between the 8-way EBCM/EBTCM connector C2 terminal and the ground.

Is the resistance within the specified range?

0-2 ohms

Go to Step 7

Go to Step 31

7
  1. Disconnect the 24-way EBCM/EBTCM connector C1.
  2. Use the J 39200 in order to measure voltage between the 24-way EBCM/EBTCM connector terminal B12 and ground.

Is the voltage equal to or greater than the specified voltage?

10 V

Go to Step 8

Go to Step 32

8
  1. Turn the ignition to the RUN position.

    2. Do not start the engine.

  2. Use the J 39200 in order to measure voltage between the 24-way EBCM/EBTCM connector C1 terminal A9 and ground.

Is the voltage equal to or greater than the specified voltage?

10 V

Go to Step 9

Go to Step 33

9
  1. Turn the ignition switch to the OFF position.

    2. Caution: Before servicing any electrical component, the ignition and start switch must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

  2. Disconnect the negative battery cable.
  3. Disconnect the positive battery cable.
  4. Use the J 39200 in order to measure the resistance between the 8-way EBCM/EBTCM connector C2 terminal D and the negative battery cable terminal.

Is the resistance within the specified range?

0-2 ohms

Go to Step 10

Go to Step 34

10

Use the J 39200 in order to measure the resistance between the 24-way EBCM/EBTCM connector C1 terminal B12 and the positive battery cable terminal.

Is the resistance within the specified range?

0-2 ohms

Go to Step 11

Go to Step 35

11
  1. Turn the ignition to the RUN position.

    2. Do not start the engine.

  2. Use the J 39200 in order to measure the resistance between the 24-way EBCM/EBTCM connector C1 terminal A9 and the positive battery cable terminal.

Is the resistance within the specified range?

0-2 ohms

Go to Step 12

Go to Step 32

12
  1. Turn the ignition switch to the OFF position.
  2. Use the J 39200 in order to measure the resistance between the 24-way EBCM/EBTCM connector C1 terminal A1 and the DLC terminal 9.

Is the resistance within the specified range?

0-2 ohms

Go to Step 13

Go to Data Link Connector, Cell 50 in Electrical Diagnosis

13

Use the J 39200 in order to measure the resistance between the 24-way EBCM/EBTCM connector C1 terminal A1 and ground.

Is the resistance within the specified range?

OL (Infinite)

Go to Step 14

Go to Data Link Connector, Cell 50 in Electrical Diagnosis

14
  1. Inspect the following components:
    2. • The 24-way EBCM/EBTCM connector C1
    • The 8-way EBCM/EBTCM connector C2
    • The 8-way EBCM/EBTCM connector C3
    • The negative battery cable
    • The positive
  2. Inspect the components for the following conditions:
    3. • Poor terminal contact
    • Terminal corrosion
    • Damaged terminals

Are there signs of poor terminal contact, terminal corrosion, or damaged terminals?

--

Go to Step 37

Refer to Diagnostic Aids

15
  1. Connect the Scan Tool .
  2. Display DTCs.

Does the Scan Tool display any current DTCs?

--

Refer to the applicable DTC table.

Go to Step 16

16

Cycle the ignition switch from the OFF to the ON position. Don't start the engine.

Does the ABS Indicator come ON, then go OFF after three seconds?

--

Go to Step 21

Go to Step 17

17

Does the ABS Indicator Come ON and stay ON?

--

Refer to ABS Indicator Always On

Refer to ABS Indicator Inoperative

18

Is the vehicle ETC/TCS equipped?

--

Go to Step 19

Go to Step 21

19

Cycle the ignition switch from the OFF to the ON position. Don't start the engine.

Does the ETC/TCS Indicator come ON, then go OFF after three seconds?

--

Go to Step 21

Go to Step 20

20

Does the ETC/TCS Indicator come ON and stay ON?

--

Go to Traction Control Indicator Always On

Go to Traction Control Indicator Inoperative

21
  1. Connect the Scan Tool .
  2. Display DTC(s).

Does the Scan Tool display any history DTCs?

--

Refer to the applicable DTC table.

System OK

22
  1. Replace the fuse block ABS - BCM Fuse (10A) with a known good fuse (10A).
  2. Wait for ten seconds.
  3. Remove the fuse block ABS - BCM Fuse (10A) terminals.
  4. Use the J 39200 in order to measure the resistance between fuse block ABS - BCM Fuse (10A) terminals.

Is the resistance within the specified range?

0-2 ohms

Go to Step 39

Go to Step 23

23
  1. Disconnect the 24-way EBCM/EBTCM connector C1.
  2. Replace the fuse block ABS BCM Fuse (10A) with a known good fuse (10A).
  3. Wait for ten seconds.
  4. Remove the fuse block ABS - BCM Fuse (10A).
  5. Use the J 39200 in order to measure the resistance between fuse block ABS - BCM Fuse (10A) terminals.

Is the resistance within the specified range?

0-2 ohms

Go to Step 24

Go to Step 38

24
  1. Inspect CKT 2340 for physical damage.

    2. Physical damage may cause a short to ground with the 8-way EBCM/EBTCM connector C2 connected.

  2. Inspect the 8-way EBCM/EBTCM connector C2 and the 8-way EBCM/EBTCM harness connector C2 for physical damage.

    3. Physical damage may cause a short to ground with the 8-way EBCM/EBTCM connector C2 connected.

  3. Reconnect the 24-way EBCM/EBTCM connector C1.
  4. Reconnect the 8-way EBCM/EBTCM connector C2.
  5. Reinstall the fuse block ABS - BCM Fuse (10A).
  6. Wait for ten seconds.
  7. Remove the fuse block ABS - BCM Fuse (10A).
  8. Use the J 39200 in order to measure the resistance between the fuse block ABS - BCM Fuse (10A) terminals.

Is the resistance within the specified range?

0-2 ohms

The malfunction is intermittent or not present at this time

Go to Step 29

25
  1. Replace the fuse block ABS/ETC/TCS IGN Fuse (10A) with a known good fuse (10A).
  2. Turn the ignition switch to the RUN position.

    3. Do not start the engine.

  3. Wait for ten seconds.
  4. Turn the ignition switch to the OFF position.
  5. Remove the fuse block ABS/ETC/TCS IGN Fuse (10A).
  6. Use the J 39200 in order to measure the resistance between the fuse block ABS Fuse (10A) terminals.

Is the resistance within the specified range?

0-2 ohms

Go to Step 41

Go to Step 26

26
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the 24-way EBCM/EBTCM connector C1.
  3. Replace the fuse block ABS/ETC/TCS IGN Fuse (10A) with a known good Fuse (10A).
  4. Turn the ignition to the RUN position.

    5. Do not start the engine.

  5. Wait for ten seconds.
  6. Turn the ignition switch to the OFF position.
  7. Remove the fuse block ABS/ETC/TCS IGN Fuse (10A).
  8. Use the J 39200 in order to measure the resistance between the fuse block ABS/ETC/TCS IGN fuse (10A) terminals.

Is the resistance within the specified range?

0-2 ohms

Go to Step 27

Go to Step 40

27
  1. Inspect CKT 1339 for physical damage.

    2. Physical damage may cause a short to ground with the 24-way EBCM/EBTCM connector C1 connected.

  2. Inspect the 24-way EBCM/EBTCM connector C1 and the 24-way EBCM/EBTCM harness connector C1 for physical damage.

    3. Physical damage may cause a short to ground with the 24-way EBCM/EBTCM connector C1 connected.

  3. Reconnect the 24-way EBCM/EBTCM connector C1.
  4. Reconnect the 8-way EBCM/EBTCM connector C2.
  5. Reinstall the fuse block ABS/ETC/TCS IGN Fuse (10A).
  6. Turn the engine to the RUN position.

    7. Do not start the engine.

  7. Wait for ten seconds.
  8. Turn the ignition switch to the OFF position.
  9. Remove the fuse block ABS/ETC/TCS IGN Fuse (10A).
  10. Use the J 39200 in order to measure the resistance between the fuse block ABS/ETC/TCS IGN Fuse (10A) terminals.

Is the resistance within the specified range?

0-2 ohms

The malfunction is intermittent or not present at this time

Go to Step 28

28
  1. Replace the EBCM/EBTCM.
  2. Replace the fuse block ABS/ETC/TCS IGN Fuse (10A) with a known good fuse (10A).

Is the repair complete?

--

Go to Step 1

--

29
  1. Replace the EBCM/EBTCM.
  2. Replace the fuse block ABS Fuse (10A) with a known good fuse (10A).

Is the repair complete?

--

Go to Step 1

--

30

Disconnect and reconnect the Scan Tool in order to ensure a good connection.

Is the Scan Tool correctly connected?

--

Go to Step 1

--

31

Repair the open or high resistance in CKT 251.

Is the repair complete?

--

Go to Step 1

--

32

Repair the open or high resistance in CKT 2340.

Is the repair complete?

--

Go to Step 1

--

33

Repair the open or high resistance in CKT 1339.

Is the repair complete?

--

Go to Step 1

--

34

Repair the open or high resistance in any of the following components:

    • The negative battery cable
    • The negative battery cable terminals
    • The negative battery cable connections

Is the repair complete?

--

Go to Step 1

--

35

Repair the high resistance in CKT 2340 or the voltage feed circuits for the fuse block ABS - BCM Fuse (10A).

Is the repair complete?

--

Go to Step 1

--

36

Repair the open or high resistance in one of the following circuits:

    • CKT 1339
    • CKT 3
    • CKT 1

Is the repair complete?

--

Go to Step 1

--

37

Replace the terminals or the connectors that exhibit the following conditions:

    • Poor terminal contact
    • Terminal corrosion
    • Damaged terminals

Is the repair complete?

--

Go to Step 1

--

38

Repair the short to ground in CKT 2340.

Is the repair complete?

--

Go to Step 22

--

39

Reinstall the fuse block ABS - BCM Fuse (10A).

Is the installation complete?

--

Go to Step 1

--

40

Repair the short to ground in CKT 1339.

Is the repair complete?

--

Go to Step 25

--

41

Reinstall the fuse block ABS/ETC/TCS IGN Fuse (10A).

Is the installation complete?

--

Go to Step 1

--

42

Replace the EBCM/EBTCM.

Is the repair complete?

--

Go to Step 1

--