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DISCUSSION => Electrical => Topic started by: jakeb on March 29, 2008, 06:44:45 AM

Title: tach signal
Post by: jakeb on March 29, 2008, 06:44:45 AM

Does anyone know how the tach signal works?  I have a m42 in my 2002 and trying to get the stock 2002 tach to work.  I connected it to the signal off the c101 plug but not getting anything.  So trying to figure out how I can get it to work or if I should go with an after market gauge.  

I was able to really drive the car yesterday and it is fun fun fun.  The sound when you stomp on it is pretty insane.  I am running two straight trough magnaflows.  I will have to take a short video of it.

Title: tach signal
Post by: christod on April 07, 2008, 06:35:08 PM

Jake,
Ive got an e21 with an m42 swapped in and Ive run into similar problems.
Heres a post string I started some time ago that should shed some light on the situation.

http://forums.bimmerforums.com/forum/showthread.php?t=946870&highlight=pinouts

Hope it helps!

Title: tach signal
Post by: christod on April 07, 2008, 06:42:07 PM

Also, if you want to spend a little money ($80 or so), this seems like the easiest and least finicky solution.

Title: tach signal
Post by: christod on April 07, 2008, 06:42:37 PM

http://www.msdignition.com/ignition_27_a_8913.htm

Title: tach signal
Post by: MLM on November 03, 2010, 05:56:38 PM

Reviving a old thread sorry..

I am wiring in an aftermarket engine management system which outputs a 12v pulse for RPM. Will this work with a E36 guage cluster or does it require a 5v signal?

What have others done for RPM signals to standard guages when using a aftermarket system?

Any info on what the guage cluste expects as a signal much appreciated..

Title: tach signal
Post by: DesktopDave on November 04, 2010, 08:40:08 AM

It might be that the tach gets an AC signal...and the MSD linky above is down.  Here's a link for you (not sure how helpful it'll be): http://m3forum.net/m3forum/showthread.php?t=322373

If the car is still running, test that OBDII port pin 9 & see what it pulses at, AC or DC.

Title: tach signal
Post by: MLM on November 04, 2010, 02:52:41 PM

CheersDave,

I should have done that before i yoinked out the the loom and ecu. Hindsight is a wonderful thing.

I know of others running my ecu in e30's and they connected it right up but i just want to tripple check before blowing somthing up. I have the option to adjust duty cycle etc on the ecu so may start concervative and work up..

Title: tach signal
Post by: DesktopDave on November 04, 2010, 03:56:55 PM

I'm pretty sure it's not a very powerful signal...I'd be willing to bet that 12vac and 5vac will both work.  YMMV  The caps in the cluster are cheap but not so much fun to replace.