Ignitor circuit details needed.

[misterforager]

Hello,

Can anybody tell me where I can find the internal circuit diagram for a 4AGE coil ignitor? The coil/ignitor is from a 1985 UK spec AE86 and is fitted to my Triumph Spitfire project (4AGE engine/T50 box). I hasten to add that I did not break an AE86 for this! The engine and box were imported from Japan many, many years ago and the the rest of the parts from a written off rally car.
The reason I need the schematic is that the car has a pseudo-classic electronic tachometer (CAi gauges) and does not work using the ignitor's raw tacho output. The ignitor tacho output signal is derived from the IGT pulses (from the ECU), but is not simply a direct connection to the coil -ve terminal. A temporary connection to an old O/E AE86 tacho works - so the ignitor is ok. Part numbers on ignitor are:-

ND part number 131100-3701
Toyota part no. 89620-12270

Please does anyone have a schematic for this ignitor - or can somebody pull apart a broken/faulty one and work out the circuitry from that? Maybe someone out there can sell me a faulty/scrap ignitor of the same type? Is there a website that has archived N-D diagrams? Would be useful to know the ECU internals too, in case of future faults and repair.

As for the tacho problem, I have electronics skills, so feel free to chat technical stuff e.g. is the signal source open-collector/drain etc. I have looked at the excellent info at this link...

http://www.autoshop101.com/forms/h39.pdf

...but it only briefly mentions the ignitor's tachometer signal (no detail).

Another way to solve the problem might be to analyse the Denso tachometer. The type fitted to the AE86 has a 30K resistor feeding the IG-signal (tacho output from ignitor) into a chip with device number T2685A. I have trawled the internet and cannot find a datasheet for this IC. If I had a schematic for the AE86 rev counter, I could work out what the electronics does with the IG- signal and put together a simple interface to my aftermarket rev counter. Please note once again that IG- (as labelled on the back of the AE86 instrument pod PCB) should not be confused with the coil -ve terminal, they are different signals.


Also, note that I don't need external wiring diagrams - got all that stuff!

Thanks to you all for any help you can offer.