Any auto electrician wiz kids out there?

So... to get my Tachometer to work in the E30 with the SR20 you have to make a small circuit board that boosts the 5V Nissan signal to 12V for the BMW tacho....

I have made the board following what this guy did... and using a multimeter It has boosted it from the Nissan ECU wire to 12v..... but, I still have no revs..

Can someone confirm what colour wire it should be out of the 76pin plug (4-3-3-3) as I have used the blue/black line as shown here....

If it is the correct wire then any other suggestions as to how I can get the E30 tacho working?....

Got mapping next Thursday so ideally want this working first

https://uploads.tapatalk-cdn.com/201...8a29b8091c.jpghttps://uploads.tapatalk-cdn.com/201...f9b1557c80.jpghttps://uploads.tapatalk-cdn.com/201...dab03cbdbc.jpg


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to confirm, you have the correct wire for the tacho from the nissan side.

is it a straightcam sr20? just thinking the earlier s13 engines/tacho sr/ca use a negative pulse tacho signal (negative-off), whereas the later sr20 as fitted to s14/a use and alternating pulse (negative-5v). We usually have issues getting the tacho to work when fitting a later sr20 into a s13. In this case you need to fit a 33k pull up resistor to the blue/black wire on the ecu connector.

im thinking, if youve got an earlier straight cam and the bmw tacho needs a negative-12v pulse then youll need to fit a pull up resistor to get that. You could quite easily fit that to your pcb.

just a thought, and its something to check

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Originally Posted by norfy

to confirm, you have the correct wire for the tacho from the nissan side.

is it a straightcam sr20? just thinking the earlier s13 engines/tacho sr/ca use a negative pulse tacho signal (negative-off), whereas the later sr20 as fitted to s14/a use and alternating pulse (negative-5v). We usually have issues getting the tacho to work when fitting a later sr20 into a s13. In this case you need to fit a 33k pull up resistor to the blue/black wire on the ecu connector.

im thinking, if youve got an earlier straight cam and the bmw tacho needs a negative-12v pulse then youll need to fit a pull up resistor to get that. You could quite easily fit that to your pcb.

just a thought, and its something to check

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Mines a S14 blacktop (vvt)

I was reading something online that when a conversion is done for the S13 to SR20DET you need to use a wire from the CAS for the tachometer to work.

Might just check the board iv made to make sure the resistors haven't burnt out.


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I can't remember it exactly as it was a yr ago, but i believe this is the scheme I used for wiring in my apexi RSM which also requires the tach signal. I also have a zenki, so 4-3-3-3. Judging by the pictures, you seem to have the correct wire
https://prjktmayhem.files.wordpress....14zsr20det.jpg

Hi,

i've tried it myself (no internet wisdom). using 7.5Kohm resistor pullup to switched 12V makes the signal a clean 0to12v square pulse. I got it on scope view but not on this computer.

Quote:

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Originally Posted by KennyJ

Hi,

i've tried it myself (no internet wisdom). using 7.5Kohm resistor pullup to switched 12V makes the signal a clean 0to12v square pulse. I got it on scope view but not on this computer.

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Tried a couple different things today but still no joy, getting frustrated now [emoji30]


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I had a similar problem when doing a conversion on S14 uk spec Sr20det vvt. I used a different wire off the ecu loom. Il check it for you and post it . But top of my head it was the red and yellow wire. But il have to confirm

Quote:

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Originally Posted by s12_drift

I had a similar problem when doing a conversion on S14 uk spec Sr20det vvt. I used a different wire off the ecu loom. Il check it for you and post it . But top of my head it was the red and yellow wire. But il have to confirm

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Great stuff if you can mate appreciate it!


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