Tacho Issue

[toneski]

hey im in the middle of doing the rb20 ecu with a rb25 tune chip on a rb25 but ive connected the computer and the car runs fine but no tacho just wondering if you need to change the tacho wiring on the ecu from pin 7 to pin 5 to suit the rb20 ecu, has any one tryed to put a factory rb20 ecu on there rb25 to see what happens and did the tacho work i ask this cause im suss my my chip any help is appreciated

[Dose Pipe Sutututu]

hey im in the middle of doing the rb20 ecu with a rb25 tune chip on a rb25 but ive connected the computer and the car runs fine but no tacho just wondering if you need to change the tacho wiring on the ecu from pin 7 to pin 5 to suit the rb20 ecu, has any one tryed to put a factory rb20 ecu on there rb25 to see what happens and did the tacho work i ask this cause im suss my my chip any help is appreciated

You should grab both ECU pin-outs and compare them and see where the tacho lines go, then switch the pins as required.

I've heard of a few people using RB20DET ecus on their RB25DETs, but then you lose VCT function if I am not mistaken, I've read you could wire up a simple shift light or something similiar to trigger the VCT component at certain rev ranges.

[toneski]

pin outs for tacho seem to be simialar and ive tryed a 10k resistor pull up curcit but no luck any more ideas im trying not to have a big external tacho but gotta do what i gotta do i guess