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.
1985 Porsche 928 AutomaticFACTORY OEM SERVICE PROCEDURE
Speed/Reference Mark Sensor
NOTE:
This test can only be made with an oscilloscope. Adjust workshop oscilloscope to supplier's instructions.
- Connect positive test lead to terminal 7 and connect negative test lead to terminal 19 of disconnected EZF control unit plug. Turn engine with starter. Screen should display "sine" oscillation of at least 2.5 V (speed) with an integrated higher amplitude (reference mark).
- Sensor distance cannot be adjusted. If insufficient (2.5 V speed) or no deflection is displayed on screen, check for proper connections. Check wire resistance at connections or replace sensor. See Fig 1 .
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.