I guess I forgot a detail in my description. It should say " when the drive is shifting, the interrupter pulses the negative lead of the coil.
The engine runs now, I just need to get the shifter working so it will not short the coil (as the carbureted systems do) and cause the ecm to put out errors.
You could actually accomplish a similar function within the ecm. The ignition cut is to reduce the sudden application of torque to the drive. If the 4V signal is timed correctly you could tune the ecm to retard timing during the shift. If the 4V signal only occurs between shifter positions it would work well. The ecm can reduce timing based on p/n input. The timing would change during the transition and return to original once the shifter is placed fully in gear. The only question is what is the minimum voltage change needed for the ecm to detect the change in state. The sensor is originally 12V so the closest to stock design would also supply 12V.any ideas on the simplest circuit possible are welcome.
That would be great. I have a 16146299. I have not found a complete pinout for that ecm yet. The shift interrupter put out 4 volt pulses during the shifts there is a switch on a mechanical linkage with a bunch of monkey motion that can " sense" that the outdrive is in the midst of shifting.
The pinout of the '299 is identical to the '7747.
The man who says something is impossible, is usually interrupted by the man doing it.
That's great! Now, if I had the pinout for the 7747, I would be set.
Both pinouts will be in the subforum that has bin files as well.
The man who says something is impossible, is usually interrupted by the man doing it.
Hmm...knock sensor input looks interesting. The boat has no knock sensor, but if that input causes the timing to retard, that could be a great way to do the shift...
Anyone know the required voltage to that pin to get the timing to retard? Is it a simple digital input or is it an analogue input that retards the timing based on the magnitude of the input?
Not the best way. ECM runs through sensor test sequence before utilizing sensor input. Test sequence won't initialize if engine is idling.
Well, it was a great idea while it lasted...Originally Posted by 1project2many
I guess it would make sense that the ECM would figure that an idling engine is not knocking...
Any other ideas on how to use a direct 4 volt input to the ECM to tell it to retard the timing?
I used an interupter to operate a normally closed relay to break the signal between the ignition control module and the coil on the ground side. Doing this droppd the spark for a few tenths of a seconds, but allowed the ECM to still read the RPM signal. As soon as the dog clutch engaged the rpm would drop and the stall saver would keep the engine idling. I had to do some tweaking with the stall saver enter/exit rpm to keep the rpm more or less stable while shifting.
Last edited by Fast355; 12-15-2014 at 09:57 PM.
Thanks for the idea on the relay. Is the "stall saver" a property of the ecm?
It was a relay that I was getting at earlier, but with only 4V a standard Bosch type relay wouldn't work. You'd still need a small amplifier circuit to drive the relay (Only about a dozen ways to do that haha).
I was going to suggest interrupting the tan/black bypass instead of the coil drive circuit directly, but then remembered that this would cause a check engine light if a simple interrupt circuit is used. I have half a thought on how I would do this without a CEL appearing, but this would only be useful if returning base timing is the desired result AND it would limit torque enough.
The man who says something is impossible, is usually interrupted by the man doing it.
You do realize that you can buy 6V automotive type relays and that the 6v relay would likely trigger just fine on 4 volts.
I have some 5 volt relays in stock. I was trying to stay away from relays. It, it would be simpler than the other circuit. You know what happens when you turn loose an E.E. On an electrical issue...
Darn, it was the bypass wire I was considering. But you are right about the check engine light. Didn't even think of that but now recall the light being on when I was setting the base timing.
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