Error Messages and Codes 3-45
Reflective Sensor Procedure 
Refer to the figure below during this procedure..
Troubleshooting References 
Applicable Parts Wiring and Plug/Jack Map References
■ Reflective Sensor
■ Engine Control Board
Troubleshooting Procedure 
Step Actions and Questions Yes No
1
1. Enter service diagnostics and run the 
Reflective Sensor test.
2. Does the sensor change state from L 
to H when blocked?
Replace the 
sensor.
Go to step 2
2
1. Measure Pin 2 to ground.
2. Is there +5 VDC?
Go to step 4. Go to step 3.
3
1. Check the wire between Pin 2 and 
engine control board Pin 8 for an open 
circuit or poor contact.
2. Is the wiring OK?
Replace the 
board.
Repair or replace 
the wiring 
harness.
4
1. Is there +5 VDC between sensor Pin 1 
and Pin 3?
Replace the 
sensor.
Go to step 5.
5
1. Is there +5 VDC between engine 
control board Pin 4 and Pin 5?
Go to step 6. Replace the 
engine control 
board.
6
1. Check the wiring to Pin 4 and sensor 
Pin 1 and Pin 5 to sensor Pin 3 for an 
open or poor circuit.
2. Is the wiring OK?
Replace the 
engine control 
board.
Replace the 
wiring harness.
7750-343
76
CONTROL
LOGIC
PWB
PL
PWB
PL
DC ROM
DC ROM
+5VDC
+5VDC
4
5
1
3
2
8
DOUBLE
PLUG
SENSOR
PL
J121