1985 Mazda GLC BaseFACTORY OEM SERVICE PROCEDURE

Vacuum Switches

  1. The 3 vacuum switches are located on the firewall behind the carburetor. Switches No. 1 and 2 use same 3-terminal electrical connector. No. 3 uses separate 2-terminal connector. Switch No. 2 is mounted above No. 1.
  2. Disconnect electrical connector and vacuum hoses. Connect hand-operated vacuum pump and circuit tester to each valve individually and check their calibration.
  3. To test switch No. 1, connect positive lead of tester to Blue/Red wire terminal of connector, and negative lead to Green/Yellow terminal. Slowly apply vacuum. Switch should close at 4.3-5.1 in. Hg.
  4. To test switch No. 2, connect positive lead of tester to Blue/White wire terminal. Slowly apply vacuum. Switch should close 7.9-8.3 in. Hg.
  5. On switch No. 3, connect positive lead of tester to Yellow/Green wire terminal and negative lead to Black terminal. Slowly apply vacuum. Switch should close at 13.8-15.4 in. Hg.
Factory Service Tools

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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.

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