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[Datsun 1200 encyclopedia]

Nissan Optical CAS

From Datsun 1200 Club

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Categories: Engine Electrical System | Ignition Modifications

The famous E15ET turbo distributor fits in an A12 and uses an optical crank angle sensor (CAS). Optical CAS was used as a trigger for ECU-based electronic spark control. 280ZX Turbo used it as did S13 and many other Nissans.



Nissan optical sensor & wheel
174_4c7b4a0d71319.jpgUpload click to view

See Main Article: Hitachi D4P Distributor

Under the cover plate is a trigger wheel for the ECU.
174_4c7b4a1edd218.jpgUpload click to view
Photo: Mitsubishi T4T84471 6626, Nissan 22100-27M15 from USA 1987 KPB12

The crank angle sensor is a thin aluminum disc, which is actually perforated 360 times. In this photo you can make out the screw under the disc, seen through the perforations.
174_4c7f162a50005.jpgUpload click to view
retouched photo (marked to show degrees)

Note the second (inner) row of perforations. These are the Cam position marks.

The photosensor is a Mitsubishi unit that read light pulse through the slits in the trigger wheel

E-series CAS

A.k.a. Crankshaft Position Sensor (CPS).

Fits in Datsun 1200 engine. Only the A12 distributor gear needs to be swapped. For A14/A15 and newer A12, the hold-down needs to be modified

E16I throttle-body fuel injection
E15ET EGI multi-port fuel injection

MITSUBISHI Crank Angle Sensor J912 (NISSAN 22100-53J11)
174_4c7f164e33b15.jpgUpload click to view

Rock auto
1987-1994 Subaru DL/GL/Loyal
1987-1989 Subaru XT
1993-1998 Mercury Villager 3.0
1991-1994 Infiniti G20 SR20DE
1988-1990 Isuzu Trooper 2.6/2.8
1984-1986 Nissan S12 200SX CA18ET
1989-1990 Nissan S13 240SX KA24E
1981-1983 Nissan S130 280ZX Turbo
1984-1989 Nissan Z31 300ZX VG30/VG30T
1986 Nissan 720 Z24I
1990 Nissan Axxess KA24E
1986-1994 Nissan D21 Z24I, VG30, KA24
1985-1994 Nissan Maxima VG30E
1992-1993 Nissan NX GA16DE, SR20DE
and many more Nissan



J920 sensor
J565A sensor

Two version: CAS vs CAS/Distributor. The Turbo CAS for Coil-On-Plug ignition

SR20 CAS converted for use with A-series engine.
14977_4ecedc7624fbd.jpgUpload click to view

The SR shaft is longer than the A-series distributor
67E40960-C0CF-4902-8BA6-B047769BB184.jpgPost click for topic

The gear needs to be swapped
22C14069-A332-49E4-8C1C-C619B9D026C9.jpgPost click for topic

Mods likely include: 1) Shortening shaft and 2) shortening housing

SR20 CAS unit disassembled
B7434629-3669-40AE-95C0-CBCB7690E4BE.jpgPost click for topic

RWD SR20DET bolts to front left side of head (RS13 engine shown)
3760.jpgAlbum 3760

FWD SR20DE bolts to back of head (GRi-R shown)


KA is an L-series descendent so uses a distributor like the L20B but with a gear on the end.

Has an 8-2-2-2 slit wheel.

J563 S13 KA24
Ignition Optic Sensor Kit


J917 CA18DE
737_4e2ec8c5cb4dd.jpgUpload click to view

Mounts on the front of the CA18, directly at the end of the left camshaft

1988 Nissan Pulsar NX with CA18DE engine
* Nissan 23731-85M10
* CARDONE 84S5405/31S5405 (from 6/88)
* Spectra NS52

174_56935d2f36adc.jpgPost 475290 174_56935d3aadf6c.jpgPost 475290 174_56935d466a06e.jpgPost 475290


rally1200: the FJ20 dissy has 2 outputs

1. 4 pulses per revolution
2. Reference lots of pulses (360?) per revolution (donít use)

for my setup i had to drill a small hole in the optic plate to create a 5 pulse next to number 1 pulse (easily done)


Nissan discs vary by CPS (inner ring).

*   4-2-2-2 wheel FJ, KA and E engines
* 16-12-8-4 wheel: SR, CA18 engines
* varying-slot wheel: Mitsu engines

16-12-8-4 wheel

4-2-2-2 (?) wheel S13 KA24DE vs SR20DE

FJ20ET wheel has extra round holes

Circular Center hole wheel

Aftermarket low-resolution (GM pattern) wheel
"missing tooth" 12-1 at "crank" speed (24-2 wheel)

Mitsubishi Engines

4G63 sensor J918 - 1990-1994 Mitsubishi & 1992-1995 Hyundai Elantra
1.8, 2.0 & 2.4 DOHC Sirius 4G6 engines

6G72 sensor 928 - notice the wheel has a different pattern from the 4-cylinder.
CPS 'T1T49371 R' from Mitsubishi 3000 GT H Constant-pattern trigger wheels - similar to the Nissan wheel - are available from the aftermarket.

Information on using with MegaSquirt ECU.

Red +12v
Black  Ground
White Cam signal
Yellow Crank signal

Using With A-series

E-series distributor with CASE can be used as a trigger for ECU-based electronic spark control and for Sequential fuel injection.

See D4P

CA or SR CAS can be custom-fitted to an old A-series distributor (and then Crank Trigger ignition will be required, since you no longer have a working distributor).

CA CAS grafted to A-series distributor
14895.jpgAlbum 14895

SR CAS can be modified to fit into the A-series distributor spot. See #SR section above.

Coil On Plug

Cam Angle Sensor is required for Coil-On-Plug ignition.

See main article: COP

Distributor-less Multi-coil ignition does not require CAS. See Crank Trigger

Control Box


A stock Nissan ECU can be used with an A-series engine. Use it with all the stock Fuel Injection parts from the donor Nissan. For spark-only control, leave the injector harness unplugged. Custom spark maps cab be programmed.


MegaSquirt III supports Nissan Optical CAS, with the latest firmware download.

MegaSquirt 2 partially supports Nissan optical wheels, for use with ignition timing (support for spark maps and coil packs). For actual CAS portion, an aftermarket low-resolution wheel is required.

Nissan optical CAS/CPS unit can be used to trigger MegaSquirt ECU for electronic spark control of coil packs and for batchfire EFI. MegaSquirt III with the latest firmware download can use the stock Nissan trigger wheels to support sequential fuel injection and/or Coil-On-Plug.

See Main Article: COP

DIYAutoTune Nissan wheels

Aftermarket 50mm GM-pattern trigger wheel for Nissan CAS

  • KA and SR engines
  • Some SR uses 54mm wheel
  • Some KA24E uses 54mm wheel
  • Does not fit CA, RB or VG engine

Can also be used with MS-III, although the stock Nissan wheel works with MegaSquirt 3 now.


Newer model Haltech ECUs supports Nissan Optical CAS. 


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