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cant see cas trigger one

s munro

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 Just installed a 24 tooth CAS wheel for my rb25det. When i tried scoping the triggers to make sure they were there i only

found the 2nd trigger present. I check all the settings which im sure are correct. I unbolted cas from the engine and spun by hand

and found the 1st trigger will only appear if you spin it relatively fast (by hand standard). I know the engine is spinning fast enough to start.

The engine will start and run with my other cas which is a standard 360 wheel. 

Any ideas?



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Interesting you can not see trigger 1 on the scope, this would tend to indicate a problem with supply voltage, ground, or the sensor.

Normally when changing the nissan 360 trigger wheel for the 24 tooth wheel the ECU's trigger mode is also changed to 'Multi-tooth'.


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Thanks for the reply Scott. Found the issue. The brand new optical sensor was faulty.. 

But i now have a second issue. Ive put the cas back together with the 24 tooth wheel with another sensor. When you scope the trigger the Trigger one is showing, but it has an extra

spike in between the normal trigger pattern.  I tried another cas with a 24 tooth wheel which displayed the same scope pattern...

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Afternoon Dave,

here is a screen shot of both triggers from the g4+

I have tested this with my friends g4 in my car and the car runs fine. im started to think there is something wrong with my g4+

help would be greatly appreciated

Simon M


trig scope.jpg

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Hi Simon,

Are you sure this is the correct 24 tooth disc for your optical sensor? There are different 24tooth discs available for different Nissan engines. We have seen this problem before when the wrong disc was fitted. The problem lied in the diameter of the disc and the width's of the gaps relative to the viewing area of the optical pickup.

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  • 3 months later...

I would expect to use the following settings:

  • Trigger Mode: Multi-tooth
  • Trigger Priority: Trig 1
  • RPM Filtering: 1 - Default

Trigger 1

  • Trigger 1 Type: Optical/Hall
  • Trigger 1 Filtering: Level 1 (Low)
  • Trigger 1 Pullup: ON
  • Trig 1 Edge: Falling
  • Multi-Tooth Posn: Cam
  • Tooth Count: 24

Trigger 2

  • Trigger 2 Type: Optical/Hall
  • Trigger 2 Filtering: Level 1 (Low)
  • Trigger 2 Pullup: ON
  • Trig 2 Edge: Falling
  • Sync Mode: Cam Pulse 1x

You will need to set the base-timing using a timing light.


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