Diagnosis

Fig. 2 Vacuum pump electrical circuit & vacuum distribution:

1. Turn ignition switch to Run position and ensure pump operates. If pump does not operate, proceed to step 2.
2. Disconnect electrical connector from pump and check for voltage at circuit 687, Fig. 2. If voltage is indicated, proceed to step 3. If no voltage is indicated, inspect circuit and fuse link and repair as necessary.
3. Check circuit 57, Fig. 2, for continuity between connector and ground. If continuity exists, replace vacuum pump. If continuity does not exist, inspect circuit 57 for an open and repair as necessary.