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GAMEOVER
March 31st, 2011, 02:12 PM
I can't find a pin assignment for Tach output on 2008 E38. Is there even an output available like pin#10 on ls1 pcm?
Aftermarket tachometer....
Taz
March 31st, 2011, 02:24 PM
Hello GameOver,

If E38 Tach output is changed from serial data to crank (for aftermarket Tach), the output is supposed to be connector C1/X1/J1 (black) pin 48. I have never done this - just in a pile of R&D files I’m collecting.

Hopefully that is correct ……


Regards,
Taz
GAMEOVER
March 31st, 2011, 02:55 PM
Thanks TAZ....Always helpful!
GMPX
March 31st, 2011, 05:30 PM
Depending on the Tacho, you will need to add a pull-up resistor to 12V on the output. 1K Ohm should do the job.
GAMEOVER
March 31st, 2011, 06:03 PM
Depending on the Tacho, you will need to add a pull-up resistor to 12V on the output. 1K Ohm should do the job.

Ok Cool....:D
Redline Motorsports
April 1st, 2011, 12:26 PM
I have to double check but we always pulled a wire that was in the coil wiring harness to run a MSD window switch which required rpm...let me see if I can remember which one it was!

Howard
GAMEOVER
April 1st, 2011, 02:46 PM
I have to double check but we always pulled a wire that was in the coil wiring harness to run a MSD window switch which required rpm...let me see if I can remember which one it was!

Howard

Really, in the coil harness...
Taz
April 1st, 2011, 03:27 PM
If you’re referring to splicing into the ignition control circuit of an individual coil - this would yield a 1 ignition pulse per 2 engine revolution output. This type of signal might be compatible with an aftermarket Tach - not sure about cylinder mode setting of the Tach (probably set to either 8 or 4 cylinder mode).


Regards,
Taz

EDIT: Recounted the ignition pulses (using all fingers, and some toes - think I got it right this time !)