Urgent advice/help needed re specs for E28 Tachometer

[Quinn 1]

Hi guys,

I have a E28 with a 1JZGTE in it and I want to wire up the factory BMW Tacho to the Toyota computer. I have had the cluster at Robinson Instruments and it's all good. I have located the pulse output pin on the Toyota computer however when connected the Tacho pops up for about 2sec then dies. The Toyota outputs a 12v signal and I was wondering if the BMW used something different? Any advice on what the voltage, impedance etc of the tacho is would be great so I can try to solve the Japanese - German no speaky problems.

Thanks!!

PS the reason it is urgent is because the dash is in pieces and I have to move it by the weekend so I'd love to solve this ASAP ;-)

Edited March 9, 2016 by Quinn

[aja540i 1906]

Im no expert but i believe the BMW tacho will just receive a 12v pulse from the coil supply and interperet that internally to display rpm,,the toyota tacho probably gets a signal from the ecu which could be a changing voltage or even a PWM signal, it might be as simple as running a 12v supply wire from the low tension side of one coil pack into the tacho, but more homework would be needed on that.

[Quinn 1]

I have spoken again to the guys at Robinsons and they said they tested the tacho with a 12v square wave pulse and it worked fine. I have checked the manual for the Toyota and it says the computer puts out a 12v signal so we are now playing around with which pin to use (apparently it's the blue plug pin no.8) I'll keep you posted so that if I solve it and anyone else is looking to re-power a bmw with a Toyota motor they'll learn from my expensive exploration.