prs Posted February 22, 2005 Share Posted February 22, 2005 Can anybody shed light on this one. I've just changed to a wasted spark setup using a Sagem/Valeo twin coil pack with an Emerald. I ran the extra wire from terminal 5 and everything is fine, engine runs ok, however my rev counter is now reading half what it should do, i've been through the manual but can't see anything obvious - any ideas. Phil S7SVN Link to comment Share on other sites More sharing options...
Manxseven Posted February 22, 2005 Share Posted February 22, 2005 Just the job for static noise tests though 😬 😬 L7 BDA Supersprint Joy here 😬 Link to comment Share on other sites More sharing options...
alicat Posted February 22, 2005 Share Posted February 22, 2005 Surely that's because you have twin coils 🤔 Alicat Link to comment Share on other sites More sharing options...
V7 SLR Posted February 22, 2005 Share Posted February 22, 2005 That's because you have your tacho being read from the original coil, or the wiring to the original coil, which is now only receiving half the number of pulses it used to. With a wasted spark set-up you need to use pin 12 on the Emerald to drive the tacho. Link to comment Share on other sites More sharing options...
prs Posted February 22, 2005 Author Share Posted February 22, 2005 V7, where do I run the wire to from pin 12, there's several wires at the back of the tacho, as you can tell I hate wiring!! give me a spanner anytime. Phil Link to comment Share on other sites More sharing options...
V7 SLR Posted February 22, 2005 Share Posted February 22, 2005 I have no idea. It depends on what tacho you have. Caterham have put quite a few different types in over the years. They're pretty simple but the implementation of shift, ignition and indicator lights in the tacho have obviously made the wiring more complex than the one I've got. If it were me I'd try to find a colour of wire that matches one coming from one of the coils. Disconnect that and see if the tacho stops working. Then, try running one outside the loom (testing only) from pin 12 to that connector on the tacho. Link to comment Share on other sites More sharing options...
Myles Posted February 22, 2005 Share Posted February 22, 2005 ISTR it's a black and white wire. Do a search on setting up aftermarket shiftlights (such as ACES sureshift units). Project Scope-Creep is underway... Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
prs Posted February 23, 2005 Author Share Posted February 23, 2005 Thanks guys, had a looksie last night and could see a black and white wire going into the tacho so will try a connection from pin 12 to that, was going to do it last night but couldn't hack the cold - thought I might get frozen upside down under the dash! 😬 Phil S7SVN Link to comment Share on other sites More sharing options...
Chris W Posted February 23, 2005 Share Posted February 23, 2005 Phil Do you have the standard CC tacho (made by Caerbont)? If so see here for switch positions on the back of the tacho. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
prs Posted February 23, 2005 Author Share Posted February 23, 2005 Chris Hey thanks, that's really useful. Like the photo of your dash! Phil S7SVN Link to comment Share on other sites More sharing options...
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