| Hi. New posting at the forum. Whats up fellas...
Just for the sake of the post, not to brag; Im a mechanic with 20 + yrs experience specializing on electrical. So I'm familiar with electrical systems. But you always learn something new every day. ??
Vehicle: 1993 Nissan 300zx twin turbo
Problem: crank no start due to 5v reference voltage dropping when crank angle sensor is plugged in.
Wires at connector.
Wire 1 ground
Wire 2 12v
Wire 3 position signal
Wire 4 reference signal 360° Ground and 12v at the CAS show no problem but...At the harness connector shows 5v on reference signal wire and position signal wire until I plug the connector to the sensor. Then wire 3 goes down to 2.3v and wire 4 goes to 800mv. Oscilloscope shows a weak and distorted signal when cranked. Ive checked all grounds I could find on the FSM to chassis, motor, battery checking out fine. Also all voltages to ecu. I have to mention I've two other CAS sensors and it does the same thing. When I pull the CAS out of the engine while still plugged in and ignition on theres 2.4 volts on the housing of the CAS. The other weird instance I found is there is 11.4 coming out of the ecu on the load side of the ecu relay when ignition switch is on. After several checks the voltage is coming out of the ECU through the white wire... Pins 49, 59 and 109. Whenever the ign switch is on. Also pin 16 black w red stripe shows 12v with ign off. (Dont know if its normal )Making the ecu turn on with the relay off the circuit. For the records ECU shows no signs of being bad, I pulled codes and only shows code 55. Everything ok. Any help on this matter is appreciated.
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13:12:18 10/07/21
