Brake Booster Pump Motor Malfunction
Diagnostic Instructions
Diagnostic Fault Information
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
Brake Booster Pump Relay B+
|
1
|
1
|
--
|
--
|
Brake Booster Pump Motor B+
|
1
|
1
|
--
|
--
|
Brake Booster Vacuum Switch Ignition
|
1
|
1
|
--
|
--
|
Brake Booster Pump Relay Coil Control
|
1
|
1
|
2
|
-
|
Brake Booster Pump Motor Control
|
2
|
1
|
--
|
--
|
Brake Booster Pump Relay Ground
|
--
|
1
|
--
|
--
|
1. Brake Booster Pump Always Off
2. Brake Booster Pump Always On
|
Circuit/System Description
The brake booster vacuum switch monitors the amount of vacuum
available to the power brake booster. When the vacuum within the
system drops, the switch within the brake booster vacuum sensor
closes allowing voltage to be supplied to the brake booster pump
relay.
Reference Information
Schematic Reference
Hydraulic Brake Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Brake Booster Vacuum Assist Description and Operation
Electrical Information Reference
Circuit/System Testing
- Ignition OFF, disconnect the X1 harness connector at
the brake booster pump relay.
- Test for less than 1 Ω between the ground circuit
terminal 1 and ground.
⇒ |
If greater than the specified range, test the
ground circuit for an open/high resistance. |
- Ignition ON, verify that a test lamp illuminates
between the B+ circuit terminal 5 and ground.
⇒ |
If the test lamp does not illuminate, test the B+
circuit for a short to ground or an open/high resistance. If the
circuit tests normal and the B+ circuit fuse is open, replace the
brake booster pump motor. |
- Disconnect the brake booster vacuum switch.
- Ignition ON, verify that a test lamp illuminates
between the ignition circuit terminal 1 and ground.
⇒ |
If the test lamp does not illuminate, test the
ignition circuit for a short to ground or an open/high resistance.
If the circuit tests normal and the B+ circuit fuse is open, test
the control circuit terminal 2 for a short to ground. |
- Verify that a test lamp does not illuminate between
the control circuit terminal 2 and ground.
⇒ |
If the test lamp illuminates, test the control
circuit for a short to voltage. |
- Connect a 10 A fused jumper wire between the
ignition circuit terminal 1 and the control circuit terminal 2.
Verify that a test lamp illuminates between the brake booster pump
relay control circuit terminal 2 X1 and ground.
⇒ |
If the test lamp does not illuminate, test the
control circuit for an open/high resistance. |
- Ignition OFF, connect the X1 harness connector at the
brake booster pump relay. Disconnect the X2 harness connector at
the brake booster pump relay. Ignition ON, verify that a test lamp
illuminates between the B+ circuit terminal 1 and ground circuit
terminal 2 at the relay.
⇒ |
If the test lamp does not illuminate, replace the
brake booster pump relay. |
- Ignition OFF, connect the X2 harness connector at the
brake booster pump relay. Verify the brake booster pump motor
activates.
⇒ |
If the brake booster pump motor does not active,
replace the brake booster pump motor. |
- If all circuits test normal, test or replace the brake
booster vacuum switch.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
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