1977 Mazda Cosmo Automatic TransFACTORY OEM SERVICE PROCEDURE

1975-78 Models

  1. Disconnect idle switch. Check continuity between switch terminals. Continuity should be as specified in IDLE SWITCH CONTINUITY table.
  2. If not, remove limiter cap on switch. Connect tachometer to engine. Connect ohmmeter to switch terminals No. 1 and 3. See Fig 1. With automatic transmission in Neutral, start engine.
  3. Slowly increase engine speed. Turn adjusting screw until continuity is broken between terminals No. 1 and 3 at RPM specified in IDLE SWITCH CONTINUITY table. Replace switch if it does not operate within specifications.
    IDLE SWITCH CONTINUITY

    Engine Status Continuity Between Terminals No Continuity Between Terminals
    Idle 1 & 3 1 & 2
    950-1050(Man. Trans.) 1 & 2 1 & 3
    1150-1250(Auto. Trans.) 1 & 2 1 & 3
    Fig 1: Idle Switch Continuity Test
    G09310042Courtesy of MAZDA MOTORS CORP.
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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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