Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1978 Mazda Cosmo Automatic TransFACTORY OEM SERVICE PROCEDURE
1974 Models
- Disconnect idle switch. Check continuity between ignition switch terminal "A" and control unit terminal "C". Continuity should exist.
- Check continuity between ignition switch terminal "A" and costing valve solenoid terminal "B" when external force is applied to switch knob (primary throttle valve in idle position). No continuity should exist.
- If there is no continuity between ignition switch and control unit and continuity between ignition switch and coasting valve solenoid, idle switch is operating properly.
- If necessary, adjust switch with engine warm. Set engine speed to idle speed by turning by-pass adjusting screw. Using accelerator pedal, increase and decrease engine speed making sure switch comes on and off. Switch cycles from on to off at 1000-1100 RPM (1100-1250 RPM with auto, trans.).
- If switch does not change at specified RPM, adjust by turning adjusting screw of idle switch lever. Turning screw counterclockwise lowers RPM. Turning screw clockwise increases RPM.
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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