sandythelandy Posted December 1, 2011 Share Posted December 1, 2011 Hi All! I'm experimenting a bit with my defender (2002) and I've got 2 wiring questions. I managed to get my hands on a cheap fuel controller and I've got it all wired in except for the rpm signal wire. Now I know the standard Td5 rpm gauge is wired into the black plug on pin 19 (white and slate stripe). The wiring manual says this is the signal input from the 2nd Throttle position sensor which produces (If i'm understanding correctly) a reducing voltage inversely proportional to pedal travel. So, my question is: How does the factory tach convert this to an accurate rpm display? especially since pedal travel does not always have a consistent relationship with rpm? My next question may possibly have a really simple answer but I'm possibly too dull to figure it out. I took the risk and wired it into the Crank sensor (+ve) feed. It worked, but the rpm readout is telling me I'm idling at just under 5000rpm. I wasn't aware that LR made F1 diesels, so i'll chalk it up to the 5x Crank sensor pickup holes on the flywheel.: Where can I wire the rpm signal wire into that will give me a voltage reading between about 4-8V in the correct pulses/rev? I had a brainfart and tried to use an injector output wire, but that didn't work either for some strange reason. (about 2500 rpm at idle) Any suggestions/ answers? I'm stumped! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted December 1, 2011 Share Posted December 1, 2011 Unless I'm missing something, pedal travel is a stable value related to where your foot it, whereas an RPM signal would be pulses, usually from the alternator W terminal or generated by the ECU based on the crank position sensor (CKP). But then again my TD5 knowledge fits on the back of a postage stamp in 96pt typeface... Quote Link to comment Share on other sites More sharing options...
Dave W Posted December 1, 2011 Share Posted December 1, 2011 There is an RPM output at the ECU but it has nothing to do with the throttle ! Pin 19 on the black ECU connector has the RPM output. If you don't have ABS there may be no connector/wire to it. If you do have ABS it will have a yellow/black wire to it. The output from the ECU is VERY low (which is why normal rev counters can't be used). Quote Link to comment Share on other sites More sharing options...
sandythelandy Posted December 1, 2011 Author Share Posted December 1, 2011 Lol, thanks anyway Fridge. Can't say mine's any better. Thanks Dave, maybe I'm reading the pinout numbers the wrong way:/. I'll see if I can get a photo up later today to make sure I've got the right pin first. Quote Link to comment Share on other sites More sharing options...
Andrew Chua Posted December 12, 2011 Share Posted December 12, 2011 The original Td5 tacho cost a whole lot of $$. for that price, i bought a nanocom and run it as a board instrument. along side i can also use it to query the engine. all works well for me. it will show you 4 things when running in instrument mode : engine rpm turbo pressure coolant temp battery voltage not to mention it also shows you a little red light when the coolant goes over 95 deg and beeps when it's over 100. so my take is don't bother with getting the Td5 tacho fitted, just plug in a nanocom. Quote Link to comment Share on other sites More sharing options...
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