corradophil 3 Posted May 15, 2012 I'm converting my 9a to run on Megaquirt and ITBs. The MS ECU does not have a rev counter feed like the original Bosch unit, so I need to find an alternative feed. On other cars I have used the low tension -ve connection on the coil to give the signal to the rev counter. Can the Corrado rev counter take it's feed directly from coil -ve? Quote Share this post Link to post Share on other sites
corradophil 3 Posted May 16, 2012 :( Has nobody done this? Quote Share this post Link to post Share on other sites
GrahamU 6 Posted May 16, 2012 Dont take this as gospal as I'm no expert in this but from my experience, the early clusters run of the coil and late of an ECU feed, which do you have? Isnt the MS ECU quite versitile and can have alot of bolt on extras, I would of thought someone on their forums will have a tacho output circuit. Quote Share this post Link to post Share on other sites
corradophil 3 Posted May 17, 2012 Mine is a late one, and is fed from the ECU. I may be able to do a 'bolt on' for megasquirt, but I would still need to know what input voltage to use. I don't want to kill my rev counter, hence doing lots of research beforehand. Quote Share this post Link to post Share on other sites
GrahamU 6 Posted May 17, 2012 Usually signal feeds are 5v but I will try to bring home an osciloscope next week and measure it. Quote Share this post Link to post Share on other sites
RedTyphoon 0 Posted May 17, 2012 (edited) Megasquirt has tacho output at pin 29. When I was using it on my VR6 engine,this circuit is what you need. Edited May 17, 2012 by RedTyphoon Quote Share this post Link to post Share on other sites
corradophil 3 Posted May 18, 2012 Usually signal feeds are 5v but I will try to bring home an osciloscope next week and measure it. That would be great if it is not too much trouble. I have been doing some reading and it appears there is a difference between early and late cars. I presume the change over was at the same point as the instrument design was updated. Early ones can be driven directly from coil -ve. Late ones (which mine is) have a feed direct from the ECU. Apparently the green cable to the ignition amplifier can be used as a signal for the rev counter. This is the thread where that info came from http://www.msextra.com/forums/viewtopic.php?f=101&t=35301 ---------- Post added at 9:46 AM ---------- Previous post was at 9:44 AM ---------- Megasquirt has tacho output at pin 29. When I was using it on my VR6 engine,this circuit is what you need. I have seen that diagram, but no mention of what pin from the ECU, so I will take a look at my MS to see what if anything is connected to pin 29. Quote Share this post Link to post Share on other sites
