GM Service Manual Online
For 1990-2009 cars only

Object Number: 537972  Size: MF
ABS Components
PWR, GND, Solenoid Valves, and Pump Motor
Handling ESD Sensitive Parts Notice
Underhood Fuse Block, RUN Fuse/IP Fuse Block, RUN Fuse, IGN-3 and Run/Accessory Relays
Underhood Fuse Block and Underhood Maxi-Fuse Block
Class 2 Serial Data Line

Circuit Description

The class 2 serial data line allows all of the modules on the line to transmit information to each other as needed. Each module is assigned an ID. All of the information sent out on the line is assigned a priority by which it is received. When the ignition is turned ON, each module begins to send and receive information. Each module on the class 2 serial data line knows what information the module needs to send out and what information the module should be receiving. What the modules do not know is which module is supposed to send the information. This information is only learned after the module has received the information needed along with the ID of the module that sent the information. This information is then remembered until the ignition switch is turned off.

Step

Action

Value(s)

Yes

No

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Turn OFF the ignition.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. Attempt to establish communication with other modules on the class 2 serial data line, such as the PCM.

Does the scan tool communicate with any other modules on the class 2 serial data line?

--

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Wiring Systems

3

  1. Turn OFF the ignition.
  2. Inspect the IP fuse block ABS (10 A) Fuse.

Is the fuse good?

--

Go to Step 4

Go to Step 7

4

Inspect the underhood fuse block ABS (50 A) Fuse.

Is the fuse good?

--

Go to Step 9

Go to Step 5

5

  1. Install a new ABS (50 A) Fuse in the underhood fuse block.
  2. Inspect the new ABS Fuse.

Is the fuse good?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Remove the ABS (50 A) Fuse from the underhood fuse block.
  3. Important: If equipped with TIM, removing battery voltage or ground from the EBCM will result in the following conditions.

       • Loss of the TIM learned tire inflation configuration parameters
       • Set DTC C1245 Low Tire Pressure Detected
    When the diagnosis is complete, inspect the tire pressures and perform the TIM reset. Refer to Tire Inflation Monitor Resetting in Tire Pressure Monitoring.

  4. Disconnect the EBCM harness connector.
  5. Connect the J 39700 universal pinout box using the J 39700-300 cable adapter to the EBCM harness connector only.
  6. Test the battery voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 15

7

  1. Turn OFF the ignition.
  2. Install a new ABS (10 A) Fuse in the IP fuse block.
  3. Turn ON the ignition, with the engine OFF.
  4. Inspect the new ABS (10 A) Fuse.

Is the fuse good?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 8

8

  1. Turn OFF the ignition.
  2. Remove the ABS (10 A) Fuse from the IP fuse block.
  3. Important: If equipped with TIM, removing battery voltage or ground from the EBCM will result in the following conditions.

       • Loss of the TIM learned tire inflation configuration parameters
       • Set DTC C1245 Low Tire Pressure Detected
    When the diagnosis is complete, inspect the tire pressures and perform the TIM reset. Refer to Tire Inflation Monitor Resetting in Tire Pressure Monitoring.

  4. Disconnect the EBCM harness connector.
  5. Connect the J 39700 universal pinout box using the J 39700-300 cable adapter to the EBCM harness connector only.
  6. Important: Disconnecting the EBCM and turning ON the ignition could cause other modules to set loss of communication DTCs (Uxxxx). Once the EBCM is reconnected, the EBCM may set one or both of the following DTCs.

       • DTC C1245 Low Tire Pressure Detected
       • DTC C1298 PCM Class 2 Serial Data Malfunction

  7. Turn ON the ignition, with the engine OFF.
  8. Test the ignition voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 15

9

  1. Install the fuses, if removed.
  2. Turn ON the ignition, with the engine OFF.
  3. Measure the voltage at the IP fuse block ABS (10 A) Fuse by probing between the fuse test terminals and a good ground.

Is the voltage within the specified range?

B+

Go to Step 10

Go to Step 16

10

Measure the voltage at the underhood fuse block ABS (50 A) Fuse by probing between the fuse test terminals and a good ground.

Is the voltage within the specified range?

B+

Go to Step 11

Go to Step 17

11

Inspect the EBCM ground, making sure the ground is clean and torqued to the proper specification. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 12

12

  1. Turn OFF the ignition.
  2. Disconnect the EBCM harness connector.
  3. Connect the J 39700 universal pinout box using the J 39700-300 cable adapter to the EBCM harness connector only.
  4. Test the module ground circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 13

13

  1. Turn ON the ignition, with the engine OFF.
  2. Test the ignition voltage circuit of the EBCM for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 14

14

Test the battery voltage circuit of the EBCM for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 15

15

Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 18

16

Inspect for poor connections at the harness connector of the IP fuse block. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 19

17

Inspect for poor connections at the harness connector of the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 21

Go to Step 20

18

Important: Perform the setup procedure for the EBCM. An unprogrammed EBCM will result in the following conditions:

   • Inoperative or poorly functioning DRP/ABS/TCS/VSES/VES/TIM (if equipped)
   • Set DTC C1248 EBCM Turned the Red Brake Warning Indicator On
   • Set DTC C1255m3 EBCM Internal Malfunction

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the repair?

--

Go to Step 21

--

19

Replace the IP fuse block. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 21

--

20

Replace the underhood fuse block. Refer to Underhood Fuse Block Replacement in Engine Electrical.

Did you complete the repair?

--

Go to Step 21

--

21

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2