Fairlineguy Posted August 29, 2017 Share Posted August 29, 2017 Any one using a tach adaptor or step up resistor to get there original Rev countre to Work with a ecu output? (RB25det s2 ) Read numerous treads some say they have been able to get it to work others haven't As I would prefer not to swop out the original unit. Quote Link to comment Share on other sites More sharing options...
Fairlineguy Posted August 31, 2017 Author Share Posted August 31, 2017 Having messaged the guys at tach match and received the following reply have decided to go with one of there units. Indeed you do have a current driven tachometer. The TachMatch TM-02-I-Drive unit will operate your stock tachometer. My understanding is that the RB25 has a tach output signal on pin 7, which is an open-collector output. Being open-collector, it needs a pull-up resistor to get the signal operative. I would recommend a 1.3k ohm pull-up resistor for use with the TachMatch. If you wish, I could install one inside the unit for you at no extra charge. I'm not sure about the maximum sink current on the RB25 pins, I've seen on the internet that folks use 1k resistors sometimes, so I'm presuming that this slightly higher value (1.3k) should be ok, it loads the pin less than 1k. I can't find the actual spec anywhere for your ECU. Quote Link to comment Share on other sites More sharing options...
Fairlineguy Posted October 7, 2017 Author Share Posted October 7, 2017 Keen to keep my original instruments with the rb25det I've just installed a TachMatch TM-02-I-Drive unit. it works a treat using the signal output from pin 7 of the ecu Quote Link to comment Share on other sites More sharing options...
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