MS2-Extra 4/1 CAS Manual

Only for use with the MS2-Extra code (HC9S12C64 based microprocessor - MS2 Daughter Board)

NOTE: Please ensure you have one of these daughter boards inside your ECU before continuing. If you have a black microprocessor, then you have an MS1 and these manuals are NOT for MS1 see here for MS1-Extra Manuals

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Please Note:

All of these instructions / diagrams are to be used at your own risk, like most things there is more than one way to do the same thing, what we have tried to do is to offer a method that we have tested or that others have tested for us. No warranty expressed or implied.

Use at your own risk.
If you do have any suggestions or settings that work please let me know Philip.Ringwood(at)

Main Index of MS2-Extra Manuals

Layout of Components -- Suggested Supply points -- List of common components and part numbers

4/1 Cam Angle Sensor (CAS)

Wiring Diagram for 4 slot CAS Sensor -- Wiring for 1 slot CAS sensor -- Schematic -- Settings

This may be a 4G91 CAS
This can be run as single coil, wasted spark or coil on plug, depending on your setup requirements.

Internal Wiring for 4 slot sensor on CAS (See HERE for second sensor wiring)

Spark outputs come on D14 (single); D14 and D16 (wasted); D14, D16, D15, JS11 (coil on plug) see HERE for options on driving the coils.



Second Trigger Input (Single slot Sensor on CAS)

Second Hall Sensor Circuit - this needs to be built for Both V3.0 and V2.2 Boards.

Single slot sensor input for CAS on pin3 of the DB37 connector on a V3.0 PCB
Single slot sensor input for CAS on pin25 of the DB37 connector on a V2.2 PCB




The Trigger Angle/Offset specifies the end of a slot in the outer ring.

When using the above circuits ensure Ignition Capture is set to Falling Edge

For correct operation it is critical that the Trigger Angle and Angle between main and return are specified correctly. For assistance in setting attach crank timing tape to your damper and disconnect the coil, then enable "middle LED indicator" on the More Ignition page. Now rotate the engine to 10 Deg BTDC (Assuming this is where you want your cranking advance). Place the CAS so the sensor just see's the start of the slot so the Middle LED just turns off. (see above diagram). Now turn the engine backwards the LED will come ON imediatley as it will now see the slot. Continue to turn it untill the LED goes out again. From the timing tape you can determine the Trigger Angle.

Also make a note of the number of degrees the LED is lit. This is for the Angle between main and return.

Spark outputs come on D14 (single); D14 and D16 (wasted); D14, D16, D15, JS11 (coil on plug) see HERE for options on driving the coils.

Suggested points for Supplies inside the V3.0 ECU



Component Pinouts

Pull up circuit diagram

List of component part numbers used in the ignition section:

DigiKey part numbers:
Farnell part numbers

2N2222A = 497-2598-5-ND
1N4001 = 1N4001/4GICT-ND
1K resistor = 1.0KQBK-ND
470R resistor = 470QBK-ND
2K resistor = 2.0KQBK-NB
330R resistor = 330QBK-ND
680R resistor = 680QBK-ND
200R resistor = 200QBK-ND
270R resistor = 270QBK-ND
1K5 resistor = 1.5KQBK-ND
4K7 resistor = 4.7KQBK-ND
0.01uF Cap = P3103-ND
4N25 (opto) = 4N25ASHORT-ND

2N2222A = 920-7120
1N4001 = 352-5326
1K resistor = 509-164
470R resistor = 543-305
2K resistor = 543-457
330R resistor = 543-263
680R resistor = 543-342
200R resistor = 543-214
270R resistor = 543-240
1K5 resistor = 543-421
4K7 resistor = 543-548
0.01uF Cap = 389-0995
4N25 (opto) = 102-1090

Please note: Above part numbers will need checking, some components will come with a minimum order in multiples of 5 and 10.

If you have a question, comment, or suggestion for this FAQ please post it on the forum.

No part of this manual may be reproduced or changed without written permission from James Murray, Ken Culver and Philip Ringwood.