note: a 22 Ohm 2W resistor also included
220 uH for RPM output "inductive pullup" (0.7A 9.5mm x 12.5mm)
If your RPM gauge originally got the input signal directly from the primary side of the ignition transformer (common for cars that originally had distributor ignition), or you know that the RPM gauge likes high voltage:
Take a free ignition output (IGBT based, not logiclevel !) and connect it to the input of the RPM gauge. Beware that injector FET or other output is not suitable, would be ruined immediately!!!.
On Roland's ALS BMW 1.6 turbo we used EC36pin10, that is i259 channel 7 as seen on GenBoard/Manual/DigitalOut/Table), configured tach_channel accordingly and used an "inductive pullup" to (switched) 12V made from a 22 Ohm and 220uH connected in series.
The inductor will make high enough voltage (up to appr 380..400V) to satisfy the RPM gauge. Don't touch it because either you or your family will be unhappy. The 22 Ohm resistor is to limit current if the output is enabled for too long due to misconfiguration or very low RPM.
Note: The 220uH value (because of the lower current limit) is not recommended for the onboard "main supply filter" unless you know for sure to load the 4 stepper (push-pull) outputs less than 0.5A total (from the +12V side: outputting 0V does not count in this case, since that only loads GND5, not the +12V supply), and therefore the ECM current draw from the positive supply is under 0.7A.
1.5 uH (5.4A 9.5mm x 12.5mm)
Probably only useful if you build your controller yourself and lost the "supply filter" inductor from the rescue-kit. 1.5uH value is not recommended for the "RPM output inductive pullup".