240D Tach mod quesiton/problem
 

I added a tach to my 240D a few weeks ago just like what was posted in this thread:

http://www.peachparts.com/shopforum/diesel-discussion/198203-diy-tach-240d-w-egr-easy.html?highlight=240d+tach

My question is why would my tach peg when the horn is honked? I just noticed this last week as a rarely use my horn. I know my grounds are good, i cleaned and tigthened all of those when i bought the car. I can't pin this one down. Other things like the compressor switch (temp dial) etc will make the tach jump just once in a while very briefly like 100-200rpm worth. The horn however will peg the tach if you hold it down. Anyone have any ideas?

Give FUNOLA a PM, maybe he can help you since he is good at these
projects.

I would guess a ground problem some where, maybe a seperate ground
for the tach?

Charlie ☺