GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 Savana 🢒 DTC 🢒 DTC C0269 or C0274 and C069 or C074 Excessive Dump/Isolation Time

Object Number: 364684 Size: MF
ABS Components Domestic
Antilock Brake System Schematics Domestic

Circuit Description

The EBCM microprocessor grounds the isolation coil to energize and close the isolation valve. This will prevent any additional brake pressure applied by the driver from reaching the wheel. Further increases in brake pressure will be prohibited. Each isolation valve is closed independently to isolate each wheel.

Conditions for Setting the DTC

Isolation time (pressure hold) exceeds 120 seconds.

Action Taken When the DTC Sets
    • The ABS indicator lamp turns on
    • The ABS disables

DTCs C0274 is and ignition latched DTC, which indicates that the above actions remain true until the ignition switch is turned to OFF (even if the cause of the DTC is intermittent).

Conditions for Clearing the DTC
    • Repair the conditions responsible for setting the DTC
    • Use the Scan Tool Clear DTCs function

Diagnostic Aids

Repair any other DTCs first. Then perform the Function Test of the scan tool in order to ensure proper operation of the ABS.

Test Description

The numbers below refer to the steps in the diagnostic table:

  1. This step determines the resistance of the power ground circuit.

    2.

  2. This step determines the battery voltage available to the EBCM.

    3.

  3. This step determines the resistance of the signal ground circuit.

    4.

  4. This step determines the ignition voltage available to the EBCM.

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2
  1. Turn the ignition switch to OFF.
  2. Disconnect the 2-way EBCM harness connector from the EBCM.
  3. Inspect the connector for damage or corrosion that could cause a loss of power to the EBCM.

Is the connector in good condition?

--

Go to Step 3

Go to Step 11

3

Using a J 39200 , measure the resistance between terminal B of the 2-way EBCM harness connector and the ground.

Is the resistance measurement within the specified range?

0-2 ohms

Go to Step 4

Go to Step 12

4

Measure the voltage between terminal A of the 2-way EBCM harness connector and the ground using a J 39200 .

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

10.0 V

Go to Step 6

Go to Step 5

5

Inspect the 60A ABS fuse.

Is the 60A ABS fuse open?

--

Go to Step 13

Go to Step 14

6
  1. Disconnect the 10-way EBCM harness connector from the EBCM.
  2. Inspect the connector for damage or corrosion that could cause a loss of power to the EBCM.

Is the connector in good condition?

--

Go to Step 7

Go to Step 15

7

Measure the resistance between terminal J of the 10-way EBCM harness connector and the ground using a J 39200 .

Is the resistance measurement within the specified range?

0-2 ohms

Go to Step 8

Go to Step 16

8

  1. Turn the ignition to RUN.
  2. Measure the voltage between terminal A of the 10-way EBCM harness connector and the ground using a J 39200 .

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

10.0 V

Go to Step 10

Go to Step 9

9

Inspect the 10-amp BRAKE fuse.

Is the fuse open?

--

Go to Step 17

Go to Step 18

10
  1. Inspect the 10-way and 2-way EBCM harness connectors for poor terminal contact or corrosion.
  2. Inspect CKT 442 , CKT 150, CKT  441 and CKT 451 for damage that could result in an intermittent open circuit.
  3. Repair any evident damage.
  4. Replace the terminals if poor contact or corrosion exists.
  5. Reconnect all the connectors.
  6. Clear all DTCs using the Scan Tool .
  7. Test drive vehicle above the 16 km/h (10 mph)

Does the DTC set as a current DTC?

--

Go to Step 19

Go to Diagnostic Aids

11

Repair the 2-way EBCM harness connector. Refer to Connector Repairs .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

12

Repair the open or the high resistance in the CKT 150. Refer to Wiring Repairs .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

13

Repair the short to ground in the CKT 442. Refer to Wiring Repairs .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

14

Repair the open or the high resistance in the CKT 442. Refer to Wiring Repairs .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

15

Repair the 10-way EBCM harness connector. Refer to Connector Repairs .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

16

Repair the open or the high resistance in the CKT 451. Refer to Wiring Repairs .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

17

Repair the short to ground in the CKT 441. Refer to Wiring Repairs .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

18

Repair the open or the high resistance in the CKT 441. Refer to Wiring Repairs .

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

19

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

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--