2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 759
10. Disconnect the harness connector at the K17 Electronic Brake Control Module (EBCM).
11. Test for infinite resistance between the vacuum pump relay control circuit terminal 85 and ground.
瀚慖f less than the specified value, test the control circuit for a short to ground.
12. Connect the KR28 Vacuum Pump Relay.
13. Engine running, momentarily connect a fused jumper wire between the control circuit terminal 35 and ground. Verify the M9 Brake Booster
Pump Motor activates.
瀚慖f the M9 Brake Booster Pump Motor does not activate, test the vacuum pump relay control circuit for an open/high resistance. If the
circuit tests normal, test or replace the KR28 Vacuum Pump Relay.
14. If all circuits test normal, replace the K17 Electronic Brake Control Module (EBCM).
Component Testing
Vacuum Pump Motor Test
1. Ignition OFF, disconnect the harness connector at the M9 Brake Booster Pump Motor.
2. Connect a 20 A fused jumper wire between the control circuit terminal 1 and B+.
3. Connect a jumper wire between the ground circuit terminal 2 and ground, verify the M9 Brake Booster Pump Motor activates.
瀚慖f the M9 Brake Booster Pump Motor does not activate, replace the M9 Brake Booster Pump Motor.
Relay Test
1. Ignition OFF, disconnect the KR28 Vacuum Pump Relay.
2. Test for 60-100 ohm between terminals 85 and 86 of the relay.
瀚慖f not within the specified range, replace the KR28 Vacuum Pump Relay.
3. Test for infinite resistance between the following terminals:
* 30 and 85
* 30 and 86
* 30 and 87
瀚慖f less than the specified value, replace the KR28 Vacuum Pump Relay.
4. Install a fused jumper wire between relay terminal 86 and B+. Install a jumper wire between relay terminal 85 and ground.
5. Test for less than 5 ohm between terminals 30 and 87.
瀚慖f greater than the specified value, replace the KR28 Vacuum Pump Relay.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Power Brake Booster Vacuum Sensor Replacement (See: Brakes and Traction Control/Power Brake Assist/Brake Booster Vacuum
Sensor/Service and Repair)
* Power Vacuum Brake Booster Replacement (See: Brakes and Traction Control/Power Brake Assist/Vacuum Brake Booster/Service and
Repair)
Control Module References (See: Testing and Inspection/Programming and Relearning) for EBCM replacement, setup and programming
C028A
DTC C028A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provide an overview of each diagnostic category.
