Scott Posted May 9, 2014 Share Posted May 9, 2014 I'm having a bit of an issue in that my dash isn't reading anything from the tacho. I start the car up but the revs stay at 0. Just trying to fault find what could be causing the issue. I've connected both of the gearbox plugs, but I was wondering if there is something obvious I have missed? Cheers Quote Link to comment Share on other sites More sharing options...
Andy Blyth Posted May 9, 2014 Share Posted May 9, 2014 On the TT, it comes from the engine ECU. Quote Link to comment Share on other sites More sharing options...
Scott Posted May 9, 2014 Author Share Posted May 9, 2014 On the TT, it comes from the engine ECU. Hmm, something strange is going on then. Would I be right in saying that the signal originates from the cam sensor? From there it goes into the ECU and then it's sent out as a signal to the tacho? The issue I'm having is that the car will fire, then die after a few seconds. I believe this suggests the cam sensor, as with a crank sensor fault it just wouldn't fire? I don't get any signal to the tacho either, so it would kind of stack up. I've got a syvecs ECU installed. Pins 35&36 are the crank and cam sensors and checking both to ground shows 1.1k ohm, which again I believe is correct. I've contacted Ryan regarding it but he's been a bit busy of late so replies can take a while. Cheers. Quote Link to comment Share on other sites More sharing options...
Andy Blyth Posted May 9, 2014 Share Posted May 9, 2014 Hmm, something strange is going on then. Would I be right in saying that the signal originates from the cam sensor? From there it goes into the ECU and then it's sent out as a signal to the tacho? I don't think so. Each of the stock cam sensors give 1 pulse every other revolution of the crank, whereas the tacho signal is 3 pulses per crank revolution. However, the cam sensor is needed to give the ECU a reference position. Maybe the Syvecs ECU needs a position reference before it begins to give a tacho signal. I'm not sure, but it's possible. Thinking about it, with the 2JZ-GTE (non-VVTI) the fact that it fires at all tells you that the cam sensor is fine. Without it, the ECU wouldn't have a clue when to fire the spark plugs and the engine wouldn't run at all - even for a few seconds. Quote Link to comment Share on other sites More sharing options...
Scott Posted May 9, 2014 Author Share Posted May 9, 2014 Hmm, I'm even more lost now then lol. Here is what the manual says.... Would it not be possible for the ECU to simply multiply the cam in signal by 3 in order to output the RPM? As for the spark, does that not come off the crank? I know I won't get any spark at all when the crank sensor is down. Quote Link to comment Share on other sites More sharing options...
bignum Posted May 9, 2014 Share Posted May 9, 2014 I thought the tacho shares its signal with the igniter, black/orange? Quote Link to comment Share on other sites More sharing options...
David P Posted May 9, 2014 Share Posted May 9, 2014 The tacho signal comes from the ignitor. Quote Link to comment Share on other sites More sharing options...
Scott Posted May 9, 2014 Author Share Posted May 9, 2014 I thought the tacho shares its signal with the igniter, black/orange? Don't think so, could be wrong though. I've attached the diagrams. From that, as suggested, the ECU generates the signal for the tacho. Going from the info above, it processes the camshaft position to generate this. Quote Link to comment Share on other sites More sharing options...
Lee P Posted May 10, 2014 Share Posted May 10, 2014 Ignitor Quote Link to comment Share on other sites More sharing options...
Fitz Posted May 10, 2014 Share Posted May 10, 2014 Have you tried to tap the tachometer hard? Sounds silly but mine stuck at 0 and I thought perhaps it needed rewiring etc. then I thought, "perhaps it's stuck" gave it a hard tap and viola. It worked. Quote Link to comment Share on other sites More sharing options...
Whitesupra95 Posted May 10, 2014 Share Posted May 10, 2014 It comes from the ignitor. Quote Link to comment Share on other sites More sharing options...
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