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Cas question. 5v in harness?


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I have a 280z with an 83 l28et swap. It has had a 3000rpm cut out for some time. I replaced the cap and rotor last night and after about 1 minute of idling fine it just shut off. Tried restarting and now i do not have injector pulse or spark. I belive the Cas has gone bad. My question is should the green signal wires coming to the Cas have 5v whenever the switch is on and the cas is unplugged? Or should they act as grounds when the optical reader goes over the slots in the encoder wheel

Edited by 280znewbie
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Of the 4 wires connected to the L28ET C.A.S., one is Battery Voltage, one is Ground, one is the 60 degree slit signal back to the ECU, and one is the 1 degree slit signal back to the ECU.  It's easiest to refer to the wiring at the CAS connector: Red = Battery Voltage, Black = GND, Green and White are the two "degree" signals back to the ECU (but I always get them mixed up).  With the rectangular 4-spade connector pulled from the distributor, make sure you have voltage and ground with the ignition on.  You can also check continuity of the green and white signal wires back to the ECU pins.  Then plug the connector back in.


You can find how to test the CAS in the 1990-1992 Infiniti M30 Factory Service Manual (probably also the Z32, Nissan Maxima - any of the VG30E distributor type engines...)  Get the FSM from Nicoclub.com.  They use the same type of optical module that the L28ET uses, and they describe how to test the CAS in their FSM (at least the M30 FSM does).


Basically you remove the distributor (with the harness wiring still attached) and rotate it slowly by hand with the ignition on.  You'll monitor the output of the green and white wires one at a time with your electrical meter.  It's pretty easy to see the six "60 degree" signals turning by hand - a little more difficult to see the "1 degree" signals.  The meter should jump to +5V momentarily as the CAS sends the pulse to the ECU.

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I already knew most of that. I'm sorry I wasn't specific enough. What I meant to ask is with the distributor unplugged should the green signal wires have 5 volts coming from the ecu and out the harness? Wasn't sure if the wires should be powered or if they should ground through the distributor

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He answered you question.


It's a gating pulse. +5V goes to the gate, the photo cel,gates a pulse that sends +5V back to the ECU.


They don't "ground through the distributor", like points, they are gated in the CAS for a signal back to,the ECU.

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