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I am installing a data logger and it has sequential shift lights so I need to find a tach signal. I read somewhere that there is a white/yellow wire at the ECU that I can tap into. Can anyone confirm or tell me the best place to splice into.
BTW, my car is a 1990 if it makes a difference.
When I installed my G2X in the ITS car I got the tach signal from a wire coming out of the ECU. I looked in the ETM in the Bentley’s and fond the wire in the harness right at the ECU. I used a saddle connection. Worked like a champ.
Michael O.
Thanks Michael, I’ll pull out my Bentley and track down the wire. I was just being lazy and figured someone else had already done it.
If you want I can guess as to what the color of the wire was. It would be a random guess but it would be fun to watch what happens if it was wrong.
Try blue/green 
Good Luck.
Michael O.
Ken,
Your electrical troubleshooting manual should be downloadable here:
http://wedophones.com/BMWManualsLead.htm
sharkd wrote:
[quote]Ken,
Your electrical troubleshooting manual should be downloadable here:
http://wedophones.com/BMWManualsLead.htm[/quote]
Thanks Dan, that electrical manual is a big help.
white/yellow wire going into the instrument cluster sounds familiar. I tried using the coil signal, but my logger really didn’t like that signal. It was too "dirty" for it. I don’t remember if the Bentley has the wire color for the tach signal, but what I remember doing was looking for the pin number of the tach signal pin and then looking at the wire going into that pin on the ECU harness.
IIRC it was pin 3 on the ECU. I held a multimeter lead on it and fluctuated the accelerator and watched for the voltage to range up and down - only took a couple of minutes. Also, not sure if yours is a G2X but I think I had to set the cylinders to something other than 6, mighta been 8. HTH.
I’m picking up my E30 this weekend. It’s an '89 325i that appears to be in good shape other than a blown engine. I got it for a good price, and I figure with a rebuilt engine I’ll know the engine will be solid!
Anyway, I’m getting excited about starting with my project and I was hoping I could get clarifcation on the Regulations regarding Data Acquisition. I currently have a Mychron in my Spec Racer Ford, and I’m a big fan of it. I’d like to put one in the E30 as well. The regs say ‘no secondary purpose’ relating to data acquisition. Does that mean it can’t be used as the tach and other engine gauges?
Sorry for jumping on this post, but it seemed related! Thanks!
It means you can’t use the data acq. to control parts of the car like engine mapping, ABS, etc. All it can do is just record and show any kind of data you want. The annoyance is that we have to retain the stock instrument cluster even though my data acq. covers up the whole area so you can’t see the cluster anyway.
traqrat wrote:
Thanks for the prompt reply! Glad I can plan on using the Mychron.
Doug J.