Tapping Into Injector Harness for CAS
03-15-2007, 01:28 AM
#1
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Injector Harness & Ign Coil Outputs
For my '99 I have a CAS from a '97 and from this schematic
http://users.forthnet.gr/ath/twikicore/extwir2.jpg
via Reverant I noticed that the CAS connects to the injector harness. Being a '99 this is not stock wiring for me. Where would be the best place to tap into for this connection when installing the CAS?
http://users.forthnet.gr/ath/twikicore/extwir2.jpg
via Reverant I noticed that the CAS connects to the injector harness. Being a '99 this is not stock wiring for me. Where would be the best place to tap into for this connection when installing the CAS?
Last edited by cjernigan; 03-15-2007 at 03:35 PM.
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03-15-2007, 02:13 AM
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so you are going to use it to trigger megasquirt right? I believe there are 3 wires needed: Power (12v I think), Ground, and the output signal. As long as you use a common ground, you could run any 12v source to it and run the signal wire back to the megasquirt.
Edit, just looked at that schematic, its different from others I have seen. Anyway, it looks like the CAS has 4 wires actually, because there is a CMP and CKP signal. Both of those wires would need to be run back to the megasquirt.
Edit, just looked at that schematic, its different from others I have seen. Anyway, it looks like the CAS has 4 wires actually, because there is a CMP and CKP signal. Both of those wires would need to be run back to the megasquirt.
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03-15-2007, 03:16 AM
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http://www.madracki.com/miata/wiring.html
That site has been very helpful to me. Its really not as complex as it seems, just follow the wiring back to the source. At first when you look at diagrams, it can be confusing, but it makes sense after a bit of studying. For a CAS, you only need it to trigger an RPM signal for the megasquirt and that will be its sole function. When you realize how all those wires work, you will see that it is just a few sensors to determine what the engine is doing (CAS, Temp, Etc) and a few output signals which tell the coils, injectors, etc what to do and when based on what the sensors are telling the ECU.
That site has been very helpful to me. Its really not as complex as it seems, just follow the wiring back to the source. At first when you look at diagrams, it can be confusing, but it makes sense after a bit of studying. For a CAS, you only need it to trigger an RPM signal for the megasquirt and that will be its sole function. When you realize how all those wires work, you will see that it is just a few sensors to determine what the engine is doing (CAS, Temp, Etc) and a few output signals which tell the coils, injectors, etc what to do and when based on what the sensors are telling the ECU.
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03-15-2007, 06:14 AM
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For my '99 I have a CAS from a '97 and from this schematic
http://users.forthnet.gr/ath/twikicore/extwir2.jpg
via Reverant I noticed that the CAS connects to the injector harness.
http://users.forthnet.gr/ath/twikicore/extwir2.jpg
via Reverant I noticed that the CAS connects to the injector harness.
ALSO, I have certain spark mods done a bit differently (as well as a knock sensor circuit and 3 stage shift lights, so please don't take this diagram as-is, you may burn stuff!
Jim
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03-15-2007, 03:27 PM
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It's not the injector harness, it's a +12V supply (see how it comes from the main relay?). Get a +12V from the MS board, you need this one to have power while the car is cranking or it will not start!
ALSO, I have certain spark mods done a bit differently (as well as a knock sensor circuit and 3 stage shift lights, so please don't take this diagram as-is, you may burn stuff!
Jim
ALSO, I have certain spark mods done a bit differently (as well as a knock sensor circuit and 3 stage shift lights, so please don't take this diagram as-is, you may burn stuff!
Jim
Kags Pinouts
20 - Air Intake Temp (ECU 2P) (red-green)
21 - Coolant Temp (ECU 2Q ) (Blue-White)
22 - Throttle Position sensor (ECU 1N) (Red)
23 - 02 Sensor (ECU 2N) (Red-Blue)
24 - RPM Signal (ECU 2E) (white)
25 - 1A RPM Signal (ECU 2I) (Black-White)
26 - TPS signal 5vref (ECU 2L) (Lt Green – White)
27 - 1B Coil (ECU 1G) (Brown-yellow)
28 - Power 12V (ECU 1B) (White – Red)
29 - 2A Coil (ECU H) (Brown)
30 - Idle Air Control (ECU 2W)
31 - Not used
32 - 33 - Tied together Injectors (ECU 2U) (Yellow)
34 - 35 - Tied together Injectors (ECU 2V) (Yellow – Black)
36 - Not Used - This ignition is not used in my setup (see 27 / 29)
37 - Not Used - I am wiring the FP to come on when the ignition is on at Diag port
Need help with this one, not sure which to use.
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03-15-2007, 05:09 PM
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As per DIYautotunes tech article. Sorry guys, being dumb again.
The Primary tach input (CKP) (Reported to be White on Miatas) is connected to pin 24 on the MegaSquirt's DB37
The Secondary tach input (CMP) (Reported to be Yellow on Miatas) is connected to pin 25 on the MegaSquirt's DB37
When wiring up your ECU later: Spark Output A will come out on pin36, and Spark Output B will come out on pin31.
The Primary tach input (CKP) (Reported to be White on Miatas) is connected to pin 24 on the MegaSquirt's DB37
The Secondary tach input (CMP) (Reported to be Yellow on Miatas) is connected to pin 25 on the MegaSquirt's DB37
When wiring up your ECU later: Spark Output A will come out on pin36, and Spark Output B will come out on pin31.
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03-15-2007, 05:21 PM
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I don't currently remember which pins I used for the spark output on the DB37 connector because I have too many mods (CAS, external MAP sensor, second baro MAP, EGT, launch control, switchable tables) forcing me to take a bit different route than what the diyautotune article said.
Jim
Jim
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