Brake Booster Pump Motor Malfunction (With J55)
Brake Booster Pump Motor Malfunction (With J55)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The brake booster vacuum sensor measures the vacuum in the brake booster assembly. The electronic brake control module supplies a 5 V reference and a low reference circuit to the brake booster vacuum sensor. The vacuum sensor supplies a voltage signal in relation to the pressure in the brake booster to the electronic brake control module. When the vacuum within the system becomes weak, the electronic brake control module turns ON the brake booster pump motor by providing battery voltage to the brake booster pump motor relay. The relay activates and supplies ground to the brake booster pump motor.
Reference Information
Schematic Reference
Hydraulic Brake Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Brake Booster Vacuum Assist Description and Operation Brake Booster Vacuum Assist
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References
Circuit/System Verification
1. Ignition ON.
2. Verify that DTC C1100 is not set.
• If the DTC is set
Refer to DTC C1100 C1100.
• If the DTC is not set
3. Verify the brake booster pump motor turns ON and OFF when commanding the Brake Booster Electric Vacuum Pump On and Off with a scan tool.
• If the brake booster pump motor does not turn ON and OFF
Refer to Circuit/System Testing.
• If the brake booster pump motor turn ON and OFF
4. Verify that the brake booster vacuum system has no damage, leakage or incorrect installation.
• If damage, leakage or incorrect installation is found
Refer to Brake Assist System Diagnosis Component Tests and General Diagnostics.
• If the inspection is OK
5. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the KR14 Brake Booster Pump Motor Relay. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the ground circuit terminal 86 and ground.
• If 10 ohms or greater
1. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Ignition ON.
4. Verify that a test lamp illuminates between the B+ circuit terminal 87 and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Ignition OFF, disconnect the harness connector at the M9 Brake Booster Pump Motor.
4. Test for infinite resistance between the brake booster pump motor control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the M9 Brake Booster Pump Motor.
• If the test lamp illuminates
5. Connect a test lamp between the control circuit terminal 85 and ground.
6. Verify the test lamp turns ON and OFF when commanding the Brake Booster Electric Vacuum Pump On and Off with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the harness connector at the K17 Electronic Brake Control Module.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K17 Electronic Brake Control Module.
• If the test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the K17 Electronic Brake Control Module, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K17 Electronic Brake Control Module.
• If the test lamp turns ON and OFF
7. Ignition OFF, connect the harness connector at the KR14 Brake Booster Pump Motor Relay. Disconnect the harness connector at the M9 Brake Booster Pump Motor.
8. Connect a test lamp between the control circuit terminal 1 and ground, ignition ON.
9. Verify the test lamp turns ON and OFF when commanding the Brake Booster Electric Vacuum Pump On and Off with a scan tool.
• If the test lamp does not turn ON and OFF
1. Ignition OFF, disconnect the harness connector at the KR14 Brake Booster Pump Motor Relay.
2. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the KR14 Brake Booster Pump Motor Relay.
• If the test lamp does turn ON and OFF
10. Connect a test lamp between the ground circuit terminal 2 and the control circuit terminal 1, ignition ON.
11. Verify the test lamp turns ON and OFF when commanding the Brake Booster Electric Vacuum Pump On and Off with a scan tool.
• If the test lamp does not turn ON and OFF
1. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If the test lamp turns ON and OFF
12. Install a 30 A fused jumper wire between the M9 Brake Booster Pump Motor terminal 1 and B+. Install a jumper wire between the M9 Brake Booster Pump Motor terminal 2 and ground.
13. Verify the M9 Brake Booster Pump Motor activates.
• If the brake booster pump motor does not activate
Replace the M9 Brake Booster Pump Motor.
• If the brake booster pump motor activates
14. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Power Brake Booster Pump Replacement Service and Repair
* Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)
* Control Module References Control Module References for Electronic Brake Control Module replacement, programming and setup.