Cooper Posted January 6, 2020 Report Share Posted January 6, 2020 Vehicle is a LJ78 Landcruiser. All up and running with no issues and I am wanting to wire an output to run the factory Tacho. I bought vehicle with the 1UZ engine conversion done running a factory 1uz ECU and have rewired with Link Tacho has never been hooked up or worked, I believe the tacho may have originally used an RPM signal from the Diesel ECU Just wondering if anyone has any experience doing this? Quote Link to comment Share on other sites More sharing options...
cj Posted January 6, 2020 Report Share Posted January 6, 2020 im guessing the orignal tacho didnt run from an ECU at all as it probbaly didnt have one, but probably from one of the diodes on the alternator instead. You could pop the tacho out and see if it looks similar to the other 90's-ish toyota tacho's where you can just bypass an input resistor to make it accept a 12v sqaure wave. I know a lot of the 4wd forums talk about sourcing tachos from the newer hilux/surfs or from petrol models and swapping the unit over. Google is probably your friend to work out the exact input pulse the tacho expects. The link can only output square wave PWM signals so you can either a) find a tacho that accepts this and swap it in b) modify some resistors etc on your tacho so it accepts this type of signal (tacho dependent) c) get a tacho booster from a few online parts stores (never tried it but apparently you can wire up the coil side only from a relay to get the same high voltage pulse) d) open up your alternator and run a wire from one of the output rectifying diodes to the tacho to get the factory design working again. This will only read correctly if the crank -> alternator diameter ratio is the same as factory. Whether C works depends on the signal it is expecting. I'm not sure if a diesel alternator signal is similar to a coil negative pulse like used on older petrol tach's Quote Link to comment Share on other sites More sharing options...
Cooper Posted January 21, 2020 Author Report Share Posted January 21, 2020 From what I understand It did run an ecu and took the engine speed signal from the diesel pump. I guess the best way would be just to trace the wires, feed it a signal from the link and see what happens. Failing that I will look at mounting an aftermarket Tacho in the dash. Quote Link to comment Share on other sites More sharing options...
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