Thread: Do P12 20v coil plugs have built in ignition modules?

If that is the case then that would explain the differences Ashton. I have 20V coils in my possession and can make sure they are 4-wire.

That makes it clear as day to me. That's exactly what I needed. The required transistor is built into the coil. You can see it right there. No other circuitry is needed.
It doesn't however show what Ashton was talking about. It only shows three wires (and the high voltage lead). Signal wire, power wire, ground wire (and high voltage output to spark plug).

Ashton?

On second look now I'm curious why the power wire (coming form pin 113) also seems to be grounded and there is some weird schematic symbol that looks like an Omega character that I'm not familiar with in the power wire on the 1st coil.

the 20v coils that i have are 3 wire, and from what i've seen online s15 coils are 3 wire as well. from what i recall i was looking at a s15 schematic that also had the same symbol which was referred to as a "loop wire."

Sorry, i thought they were 4, but yes the wires just incorporate different things from the s13/s14 coils to the s15 and p12 coils. But as it appears the 20v and S15 coils do have the built in ignitor. The s13 and s14 use an ignitor chip.

My bad on the wire count.

The 'omega' symbol could be the cylinder 1 'loop' used for checking base ignition timing as there is no other source for spark pickup as such.

Oh yah, that makes complete sense. I actually have one of those in my wiring harness right now so the tach signal can be picked up at the dyno.

Well, it sounds like this mystery is solved. Thanks everyone. =D

(FYI it is weird that they would use that for timing pick-up. In my testing, none of the wires produced correct timing information so you must get the timing info from after the coil. This involved removing the coil and attaching a small high voltage lead from the coil to the spark plug and using an inductive pickup off that.)

my sr20ve is running with s15 coils. those coils are same part number as 20v and vet coils. they are all 3 wire and in my case run off my AEM EMS. using the stock s15 coil sub harness you have one small black wire that will give you timing. if you use s13/14 coil pack sub harness it has one extra wire that goes into the igniter box and you will have trouble getting good timing with out using a traditional spark plug wire. only draw back of the s15 sub harness is smaller Gage wiring.

good to know, so you are just running the s15 coils straight to the AEM EMS box then. what are you using for the CAS?

so i just finished stripping the 20v engine harness. I didn't find this loop wire in the #1 coil wire, however did find the cap. it's a 47uF capacitor that's connected by way of a 2 prong connector. I take it this is where you would attach the timing gun to in order to check base timing?

I am using the stock distributor's cas. I would recommend using the 24-1 AEM disk. My 2.4 ve that's going in uses a hall effect sensor from mazworx