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The PHOTO-OPTIC SENSORS: A good number of auto's are using the photo-optic distributor and it looks like we will see this type of sensors on more auto's as time goes on.
This should be a fairly easy sensor to diagnose once the system is understood. With that in mind I have some information on the Photo-Optic Distributor that should help one to get a idea as to how the system works.
Photo-Optic Distributor (sensors)
The Photo-Optic Distributor has a DC Digital Signal (Square Wave)
1. A Low Resolution Signal Input = Cylinder I.D.
2. A High Resolution Signal Input = R.P.M.
3. Cam Logic Reference Voltage = Cam Trigger for Fuel Injection
4. Reference Ground
Cylinder I.D.
The 7 degree slot represents cylinder #8
The 12 degree slot represents cylinder #3
The 17 degree slot represents cylinder #5
The 22 degree slot represents cylinder #2
The four 2 degree slot represents cylinder 1, 4,6, and 7
This is a DC Digital signal Varying in degrees on time.
(Firing Order 184365721) Note: the wide 22 degree signal is before the #1 Cylinder.
The 360 Slots is the RPM, The 8 Varying Slots is the Cylinders, Rotation IC Clockwise
Photo-Optic Sensors
Need Correct Input Voltage and Ground DC Digital Signal (Square Wave) Duty Cycle Remain Constant Computer Recognizes Frequency Change Test with Lab Scope, DMM (Volts Frequency, Duty Cycle, Dwell), Logic Probe Reasons for Failure • Low Input Voltage
• Low Signal Voltage
• Bad Ground
• Bad Photo Diode
• Dirty Disk Slots (grease, oil, moisture, dirt) • Shorted or Open.
Signal Line Specification: (At Idle) High Resolution Signal: 50% duty cycle; Low Resolution Signal: 50% duty cycle and varying.
-Carlis Wilson, Auto Technician