nom

I've read through just about all the manuals/diagrams I can get my hands on & still can't find where I can get the rpm signal from the ECU... (my00) - I've read that there is one (5v digital - exactly what I'm after - also that it can be got at more easily under the dash - all very nice but there's at least 100 cables to pick from down there...), but the actual location/point doesn't seem to be noted anywhere. Or, at least, not using language such as 'rpm signal' .
Anyone know? It's getting annoying!
Ta

dnb

If you look on the back the dials on the dash there is a screw terminal marked RPM. (At least there was on my car, which is a bit older than on yours...)

This should be the RPM signal that is fed to the tahco display.

I wonder, are you fitting a head up display?

john banks

Trace it from the Link ECU manual wiring diagram.

john banks

Trace it from the Link ECU manual wiring diagram.

nom

Hmm, the Link manual was my first 'port of call', but aside from a collection of objects loosly referred to as 'speedometer and tachometer circuit', I can't find any direct reference to rpm signal... the screw terminal on the back of the dash looks more hopeful to me
However. I think I might have another plan of attack Depending on someone else's elecontronics knowledge , as all I'm trying to do is log wideband data with the other usual odds & ends so the log can be made use of... seeming I don't use lambda (nor does the ECU) for anything except for watching the pretty lights - and monitoring, I suppose - I just need to know if the Link gets upset with a possible 5v input when it's expecting, as far as I know, a 1v signal tops; and if it doesn't like the high voltage, how to reliably & accurately divide a 5v signal to a 1v one (I said my electronics knowledge was laughable, didn't I? ). This same thing was asked ages ago on the MRT forum but no-one seemed to know... or bothered to answer. Must be a common thing to want to do, I'd have thought?
Anyhoo. There we go.

Hope the holiday was good, John

john banks

Get awa you just need to dig a bit in the wiring diagram - all the colours and plug numbers/pins/male/female are there. Trace them back and you'll work out which one is the RPM signal.

Use an op amp with gain 0.2 to get you 0-1V signal. Best do this rather than assume the ECU won't mind 5V. Make sure your op amp will deal accurately with signals near 0V (offset).

nom

Yea, right, op-amps. I know what to do with those...
0.2v would be about as low as it got anyway - any less than that & that's richer than 10:1 anyway
I've started another topic anyway - that would actually be on topic - to see if anyone else has any ideas!
And will return to the wiring diagram in the mean time