Excessive Brake Pedal Effort/VAC. Pump Inop. & Warning Light on

1. With ignition On, disconnect electrical connector from vacuum pump and check for battery voltage at terminals A and B and for proper ground at terminal D. If battery voltage is indicated, proceed to step 2. If not, check fusible link, fuse and wiring circuits and repair as necessary.
2. Connect 12 volt power source to terminals A and B and ground terminal D. If pump is still inoperative, proceed to step 3. If pump now operates, refer to ``Excessive Brake Pedal Effort, Vacuum Pump Operative & Brake Warning Light On'' diagnosis.
3. Remove vacuum pump and check for sticking or shorted brushes. Check controller for damaged wires and repair as necessary. If no defects are found, replace controller.
Do not obstruct the outlet nozzle of the vacuum pump during testing. The pump diaphragm can be permanently damaged.