dum-bass Posted August 12, 2009 Share Posted August 12, 2009 Ok Cygnus, I get absolutely no voltage reference or tach response from pin #2 of the EDIS module. So I acquiesce to the possibility that my car, and everything that I do to modify it, is infested with demons! Even the simplest task turns out to be a time vampire!!! I shall return victorious... Quote Link to comment Share on other sites More sharing options...
z-ya Posted August 12, 2009 Author Share Posted August 12, 2009 Ok Cygnus, I get absolutely no voltage reference or tach response from pin #2 of the EDIS module. So I acquiesce to the possibility that my car, and everything that I do to modify it, is infested with demons! Even the simplest task turns out to be a time vampire!!! I shall return victorious... What are you using the measure the voltage? A multimeter will not work. You really need a scope to verify that there is a compatible signal. Most multimeters cannot measure voltage on a signal that is much more than 100Hz. Pete Quote Link to comment Share on other sites More sharing options...
dum-bass Posted August 15, 2009 Share Posted August 15, 2009 What are you using the measure the voltage? A multimeter will not work. You really need a scope to verify that there is a compatible signal. Most multimeters cannot measure voltage on a signal that is much more than 100Hz. Pete Yes you are right Pete, we have scopes at the shop and still couldn't get anything out of pin 2 (demons) and although your inverter design didn't work for my 280 tach, (more demons) I have still emerged victorious with a completely different diode version on the coils than the megamanual shows. I now have a strong tach signal, car runs great and the thing that baffles me is, why do some methods work for some, but not for others? Different equipment? HEHE! Quote Link to comment Share on other sites More sharing options...
Derek Posted August 15, 2009 Share Posted August 15, 2009 Yes you are right Pete, we have scopes at the shop and still couldn't get anything out of pin 2 (demons) and although your inverter design didn't work for my 280 tach, (more demons) I have still emerged victorious with a completely different diode version on the coils than the megamanual shows. I now have a strong tach signal, car runs great and the thing that baffles me is, why do some methods work for some, but not for others? Different equipment? HEHE! Can you post what arrangement you came up with. Thanks Derek Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted August 15, 2009 Share Posted August 15, 2009 I have the diodes ready to make the tach signal circuit off of the coils based on the Megamanual. I haven't neede to make the circuit yet because PIN2 has been working OK. In cold weather the tach won't work until the engine bay warms up, and when idle drops below 900rpms the tach drops out (demons) but other than that, it works. Please post your circuit as an alternative to the Megamanual option...just in case. I think PIN2 was a signal to the original Ford ECU, that the coils are working. From what I understand, if PIN2 was not sending a signal out to the original ECU, the CEL would come on in the dash. Quote Link to comment Share on other sites More sharing options...
dum-bass Posted August 15, 2009 Share Posted August 15, 2009 I'm having problems with this site today. Anyway, do this. 1.Connect the diodes cathode end (stripe) to the coil wires. 2. twist the diode ends together with the tach wire and a 1K resistor. 3. connect the other end of the 1K resistor to a 12v switched supply. 4. Now go do it and tell me it works! Quote Link to comment Share on other sites More sharing options...
dum-bass Posted August 15, 2009 Share Posted August 15, 2009 A couple more things. Go ahead and put that inline resistor, the one under the glove box, back in if youv'e taken it out. Also, the tach wire branches off and goes to the stock transistor ignition box. You should snip the blue wire in the harness connector or just unplug it. My car wouldn't even start with it still connected. Quote Link to comment Share on other sites More sharing options...
dum-bass Posted July 21, 2010 Share Posted July 21, 2010 Hey! I'm back! anyone try my method? Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted March 8, 2011 Share Posted March 8, 2011 (edited) Bump. 2 Years later and still no tach for me lol. If I can get a 1k resistor before RadioShack closes I'm going to try your method tonight and report back. If your method doesn't work I'm going to dig the tach out of the dash and remove the internal resistor per this method: http://forums.hybridz.org/index.php/topic/66137-how-to-modify-a-280z-tach-to-work-with-msd-for-free/ Maybe they accomplish the same thing? If none of that works, I'll either pull the MS box out and try Z-ya's method or just buy an autometer tach and be done with it haha. Edited March 8, 2011 by TrumpetRhapsody Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted March 9, 2011 Share Posted March 9, 2011 (edited) Ok uh... some help is needed. I added the 1K resistor to switched 12V (a 12v pullup, basically), and directly connected to the tach wire it does nothing, dead. Only when I held the two wires in my fingers did I notice that IT WORKS PERFECTLY. I guess the conductivity of my skin is enough of a buffer to make it work. I tried adding a few more 2.2K resistors inline to simulate the resistance of my skin but nothing worked. Only when I held the two wires a couple millimeters apart in my fingers could I get the tach to work. Somebody please tell me how to make this work haha. Is this an indication that I should try removing that resistor from the inside of the tach... or do I need something else? HELP! I'm at my wit's end with this. Edited March 9, 2011 by TrumpetRhapsody Quote Link to comment Share on other sites More sharing options...
dum-bass Posted March 9, 2011 Share Posted March 9, 2011 You guys did not reverse the polarity of the diodes!!!!! Quote Link to comment Share on other sites More sharing options...
dum-bass Posted March 9, 2011 Share Posted March 9, 2011 Just reverse the polarity of the diodes " striped end away from the coil" and yer all GOOD! now tell me if it works!!!!! Don't forget the 1K resitor to positive Quote Link to comment Share on other sites More sharing options...
dum-bass Posted March 9, 2011 Share Posted March 9, 2011 I am going to be famous for this!!! EDIS 280z tach wiring.... Quote Link to comment Share on other sites More sharing options...
dum-bass Posted March 9, 2011 Share Posted March 9, 2011 I am sorry guys, I just reviewed some of my earlier posts and discovered that I, Mr dum-bass, posted wrong! Just reverse the polarity of the diodes! Striped end away from the coils. Why? Because a diode is a gate valve. electrons go through one way but not the other way. If you have the striped end of the diode toward the coil, then you are impeding the flow of signal that the tach wants to see! There has been a write up before about this subject that states the opposite, but I believe that was for a 240! BTW don't forget the 1K resister to positive Quote Link to comment Share on other sites More sharing options...
dum-bass Posted March 9, 2011 Share Posted March 9, 2011 So what that means is, pins 10, 11, and 12 of the input plug of the EDIS, you should have one diode going to each one of those pins "3 diodes". Connect the BANDED ends of each one of the diodes "solder them inline on each individual wire" to the inputs of 10, 11, and 12 of the EDIS input. On the other end of the three diodes, twist all three ends together with a 1k ohm resister,then tie the other end of the resister to a 12v switched supply! Should work perfectly!!! ie, This is for the 280 tach. Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted March 9, 2011 Share Posted March 9, 2011 (edited) I've had the diodes facing the right way, that's not my problem. If no one has any suggestions i'm going to break out the scope tonight and see what i can figure out. Edited March 9, 2011 by TrumpetRhapsody Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted March 10, 2011 Share Posted March 10, 2011 (edited) I played with it more tonight. It seems like the 12v pullup doesn't really make that much of a difference in my case. With or without it, I get no movement on the tach until I pinch the wires together in my fingers separated by a couple mm. All I learned by hooking up the scope is that I don't really know how to use it Only thing I can say is that the pulses seemed taller when directly connected (maybe overwhelming the tach) and when scoped pinching with my fingers they were much shorter/more subdued. I don't know how to replicate the effect, or what to do from here. Any electrical guru's have some comments/suggestions? I know there are a few of you on here, speak up! Edited March 10, 2011 by TrumpetRhapsody Quote Link to comment Share on other sites More sharing options...
dum-bass Posted March 10, 2011 Share Posted March 10, 2011 Put the tach signal wire between the twisted ends of the diodes and the 1k resister that goes to positive. Do not use the reverse zener diode that the MEGA MANUAL calls for!! Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted March 10, 2011 Share Posted March 10, 2011 I tried that, still didn't work Quote Link to comment Share on other sites More sharing options...
TrumpetRhapsody Posted March 10, 2011 Share Posted March 10, 2011 (edited) Just dug my tach out the back of the dash (that was quite the experience), and did the resistor bridging mod. While the signal is somewhat stronger when I pinch the wires together, directly connected it's still not working. When I get home tonight I'm going to re-do all my diodes and try one last time, just in case I overheated one while soldering. At that point if it still doesn't work I'm just going to give up and order an autometer tach. Stupid 260z's. Edited March 10, 2011 by TrumpetRhapsody Quote Link to comment Share on other sites More sharing options...
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