1986 Cadillac SevilleFACTORY OEM SERVICE PROCEDURE

2.8L V6

  1. Turn ignition on. Remove wiring harness from motor and check for 12 volts at terminals "A: and "B". Check for good ground at terminal "D". See Fig 1 . If 12 volts is not present or ground not good, repair as required.
    Fig 1: Electric Vacuum Pump Terminals Terminals located on controller portion of pump.
    G13141
  2. Connect 12 volts to terminals "A" and "B". Ground terminal "D". If pump does not operate, go to step 3). If pump operates, go to step 4).
    NOTE: Pump should not draw more than 8 amps in steps 1) and 2) nor leak more than 2 in. Hg in other steps.
  3. Remove vacuum pump from vehicle. Check for stuck brush, shorted brush or broken wires in controller. If defects are found, repair as required. If no defects, replace controller.
  4. Turn ignition off. Remove inlet hose and attach hand vacuum pump to inlet. Turn ignition on. If pump runs intermittently and will not hold steady vacuum, go to step 5). If pump runs, then shuts off within 5-10 seconds when vacuum reads 10-15 in. Hg, pump is okay and a leak exists in other parts of system.
  5. Remove pump from vehicle. Remove controller assembly and "T" connector from inlet hose-to-outlet hose housing. Attach hand vacuum pump to inlet port and draw 20 in. Hg. If vacuum holds, go to step 6). If vacuum leaks down more than 2 in. Hg per minute, replace controller.
  6. Attach hand pump to housing inlet and draw 20 in. Hg. If vacuum holds, go to step 7). If vacuum leaks more than 2 in. Hg per minute, replace umbrella valve.
  7. Plug pump inlet port, attach hand pump to outlet port and draw 20 in. Hg vacuum. If vacuum holds, pump is okay and no further checks are required. If vacuum does leaks more than 2 in. Hg per minute, check outlet housing bonnet and recrimp, if necessary. If vacuum holds, pump is okay. If vacuum still does not hold, replace piston assembly inside bonnet.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.