Bob and Carol Posted January 6, 2023 Share Posted January 6, 2023 Hi Guys, I’m looking to fit a set of shift lights to my 420 and the instructions say the signal it requires is taken from the 12 volt negative ignition coil. Would anyone know where that is please? The unit I am looking to fit is a Racetronic GS20 from pawa-technology.com Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 6, 2023 Member Share Posted January 6, 2023 If you send me a Private Message with your email address I'll send you the wiring diagram for the 420.Jonathan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 6, 2023 Member Share Posted January 6, 2023 Instruction manual for the Racetronic G-Shift 20, includes:CompatibilityThe G-Shift unit is designed for use with any single or twin coil inductive type ignition system. This unit is not compatible with CDi or multiple spark ignition systems. This product will work accurately on 4-stroke engines with 1, 2, 3, 4, 6, and 8 cylinders and trigger from 1000 rpm to 20,000 rpm on all engine types.Jonathan Link to comment Share on other sites More sharing options...
7 wonders of the world Posted January 6, 2023 Share Posted January 6, 2023 DRE shift lights are neat effective and unobtrusive, easy to wire and sensibly priced too. many members obtained theirs through a bulk buy a few years backhttp://www.caraddiction.co.uk/ Link to comment Share on other sites More sharing options...
Bob and Carol Posted January 6, 2023 Author Share Posted January 6, 2023 Thanks for the link, I would sooner keep with the GS20, you will see why but may not agree, when I post a picture of them installed. Link to comment Share on other sites More sharing options...
Bob and Carol Posted January 6, 2023 Author Share Posted January 6, 2023 Thanks for the info Jonathan.I have emailed the Tacho manufacture, Racetronic and Caterham, nobody as replied as yet.I have tried the three possible connections to the Tacho without success, without an oscilloscope I can’t read the type of signal going in.Worst case is I put a sensor to read the crank shaft.Just hoping someone has done this before. Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted January 6, 2023 Share Posted January 6, 2023 Looks like it requires an inductive pulse from the coil, so tapping into the coil negative near one of the coils might work, but being a COP system with a common ground in the coil pack loom, may cause signal problems. It looks like the system is really designed for non-COP systems, so the induced back-EMF in the common coil ground may not be of the expected and detectable profile. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 6, 2023 Member Share Posted January 6, 2023 Thanks, James.It would be interesting to see what's on the tacho signal. Where are you, Bob?I'll have a look in the archives.Jonathan Link to comment Share on other sites More sharing options...
Mark w Posted January 6, 2023 Share Posted January 6, 2023 Theres a "spare " pair of wires behind the tach. One of these is ?? and the other white with a black line along it I used these for the feed for my shift lights ( DRE) .The white with black is signal . Link to comment Share on other sites More sharing options...
Mark w Posted January 6, 2023 Share Posted January 6, 2023 Link to comment Share on other sites More sharing options...
Bob and Carol Posted January 7, 2023 Author Share Posted January 7, 2023 SouthwoldSuffolk Link to comment Share on other sites More sharing options...
Bob and Carol Posted January 7, 2023 Author Share Posted January 7, 2023 That sounds good, thanks, I will have a look Monday when back home. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 7, 2023 Member Share Posted January 7, 2023 Any oscilloscopes near Southwold?: - )Jonathan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 7, 2023 Member Share Posted January 7, 2023 I can't find anything in the archives on this type of shift light units.(There's some useful documentation on how to calibrate ACES systems on Sevens, but that isn't the current problem.)Jonathan Link to comment Share on other sites More sharing options...
Bob and Carol Posted January 7, 2023 Author Share Posted January 7, 2023 If I could find out the signal type going into the tacho I could use a digital/opto type relay, would save the trouble of fitting a sensor to the crank shaft. Link to comment Share on other sites More sharing options...
Bob and Carol Posted January 7, 2023 Author Share Posted January 7, 2023 Thanks for looking Jonathan,I don't think I am using the search correctly as a Google normal does a better job than I do searching on this site. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 7, 2023 Member Share Posted January 7, 2023 You're not alone: "Search facility", includes my preferred method...... click the second link in my Signature below, and add search terms according to taste.Jonathan Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted January 7, 2023 Share Posted January 7, 2023 The ECU output signal the tachometer uses is the white/black wire that runs from pin 34 of the ECU (which is also used by the ACES shift light system), via the engine to chassis loom connector on the top centre pin to the tacho. If that signal is not of the right profile (MBE ECU tacho output is 12V square wave) or if your shift light input can't take a 12V square wave input of an impedance matched to the ECU, you may need a tacho driver like this: https://www.autometer.com/pub/media/manual/2650-561X.pdf Link to comment Share on other sites More sharing options...
Bob and Carol Posted January 8, 2023 Author Share Posted January 8, 2023 Thanks James, I will try this along with Mark's suggestion in post 10, what a great site this is for sharing info. Link to comment Share on other sites More sharing options...
Bob and Carol Posted January 12, 2023 Author Share Posted January 12, 2023 Just to feed back to those who helped and for others in the future who may wish to do a similar mod to their car.As I could not find a signal that worked from behind the dash I ran a cable to one of the COP’s, coil side of the connector for the four COP on top of the engine as there was plenty of room there to make a soldered connection.As a precaution and to try to keep the signal clean from interference from the other three COP’s, I used a screen cable and connected one end of the screen to ground.A way of getting the four shift lights as high up as possible into my eye line, I mounted them onto of the dash and used a self-adhesive mirror under the aero screen to better display the lights into my line of sight.The last picture includes Caterham's shift light limiter on. Thanks again to those who helped me. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 12, 2023 Member Share Posted January 12, 2023 Thanks for adding the solution.Jonathan Link to comment Share on other sites More sharing options...
ScottR400D Posted January 12, 2023 Share Posted January 12, 2023 Nice solution Bob. What revs have you got the lights set to? Hope you're keeping well? See you at the Feb meeting? Peter. Link to comment Share on other sites More sharing options...
Bob and Carol Posted January 13, 2023 Author Share Posted January 13, 2023 From what I have found I think the Duratec rev limiter is set at 7600 so I set each of the lights 200 RPM steps down from this. Throttling an engine that is not on load was not that easy so I will what until Carol is driving so I can look at the rev counter and change the settings to suit. At least the last shift light came on before the Caterham’s light thinking that was a starting point. Any suggestions on what the maximum revs should be or steps between lights, please post. Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted January 13, 2023 Share Posted January 13, 2023 Hi Bob,Max revs should be 7800RPM hard cut (fuel and ignition), 7600RPM soft cut (random cut to avoid upsetting car's balance). I have my last warning (flashing all LEDs on the ACEs system) set at 7500RPM as I want warning before the fuel gets cut at the rev limiter. My first amber LED comes on at 4000RPM and subsequent ones illuminate at about 600RPM intervals. I have my "Change Down" LED set to 2000RPM.The step between LEDs will be a personal preference based on what you want to achieve. I like to know where the engine is after a gear change when driving aggressively and on track, so the engine is always somewhere in the amber or red range at full throttle, but if it is just to judge where the red line is, stacking closer together would be appropriate. Link to comment Share on other sites More sharing options...
John Vine Posted January 13, 2023 Share Posted January 13, 2023 #24 Max revs should be 7800RPM hard cut (fuel and ignition), 7600RPM soft cut...That's interesting. Easimap shows my R400D (as delivered in 2008) to be a tad higherOthers on here have suggested that that's pushing things a bit for a standard crank and pistons.JV Link to comment Share on other sites More sharing options...
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