Been logging some seat time to prefect the ever elusive optimal ve table and spark table in tunerstudio. and i have to look over to the passenger seat or my mount tablet (I know, I know first world problems...) to see my rpms.. so here it goes my tacho output to m2
got me a five finger discount relay form the junkyard. and its even a volvo one
<a href="https://www.flickr.com/photos/65872230@N08/15168379817" title="tach 2 by Puff the magic wagon, on Flickr"><img src="https://farm3.staticflickr.com/2942/15168379817_2e03c7f468_z.jpg" width="480" height="640" alt="tach 2"></a>
popped it open and JB welded a bracket to the metal cover
sourced one of these. harder than you think in the great metropolis of Ottawa
<a href="https://www.flickr.com/photos/65872230@N08/15168201310" title="tach transistor by Puff the magic wagon, on Flickr"><img src="https://farm4.staticflickr.com/3858/15168201310_d6f241e4ae_z.jpg" width="480" height="640" alt="tach transistor"></a>
found this on the interwebs
<a href="https://www.flickr.com/photos/65872230@N08/15177464448" title="Toyota Tacho Negative Coil by Puff the magic wagon, on Flickr"><img src="https://farm4.staticflickr.com/3920/15177464448_df8a3f763c_n.jpg" width="320" height="272" alt="Toyota Tacho Negative Coil"></a>
read Buchka, and grosspolluter posts about the dummy coils and the volvo tachos.
decided that i was going to attach it to the bottom insted of trying to jam everything in the relays' case
took this<a href="https://www.flickr.com/photos/65872230@N08/15351722461" title="tach 13 by Puff the magic wagon, on Flickr"><img src="https://farm3.staticflickr.com/2945/15351722461_48bcd3d4f1_z.jpg" width="480" height="640" alt="tach 13"></a>
and this
<a href="https://www.flickr.com/photos/65872230@N08/15168202450" title="tach 10 by Puff the magic wagon, on Flickr"><img src="https://farm4.staticflickr.com/3926/15168202450_22c8f5df6e_z.jpg" width="480" height="640" alt="tach 10"></a>
did this
<a href="https://www.flickr.com/photos/65872230@N08/15331886306" title="tach 12 by Puff the magic wagon, on Flickr"><img src="https://farm4.staticflickr.com/3921/15331886306_3a2da773e8_z.jpg" width="480" height="640" alt="tach 12"></a>
solder the resistor to the leg of the transistor and bent it like so
<a href="https://www.flickr.com/photos/65872230@N08/15351722251" title="tach 14 by Puff the magic wagon, on Flickr"><img src="https://farm3.staticflickr.com/2943/15351722251_b5fc493d18_z.jpg" width="480" height="640" alt="tach 14"></a>
A little more solder and add some flux for because...
<a href="https://www.flickr.com/photos/65872230@N08/15351721581" title="tach 18 by Puff the magic wagon, on Flickr"><img src="https://farm3.staticflickr.com/2947/15351721581_7b5d929117_z.jpg" width="480" height="640" alt="tach 18"></a>
Add some more liquid electrical tape for good measure like this
<a href="https://www.flickr.com/photos/65872230@N08/15168386807" title="tach 16 by Puff the magic wagon, on Flickr"><img src="https://farm3.staticflickr.com/2948/15168386807_7a24fa5e93_z.jpg" width="480" height="640" alt="tach 16"></a>
take dash apart and disconnect this connector (this one has the tach pin in it) ensure by toning it out to the coil on the other side of the firewall
<a href="https://www.flickr.com/photos/65872230@N08/15351713621" title="tach 7 by Puff the magic wagon, on Flickr"><img src="https://farm3.staticflickr.com/2945/15351713621_3b09450b2e_z.jpg" width="640" height="480" alt="tach 7"></a>
And the cheese stands alone, and the cheese stands alone ..... (Pink and White) {sorry my wire toner plays what i think/reminds me of
the Farmer in the Dell nursery song}
<a href="https://www.flickr.com/photos/65872230@N08/15354583552" title="tach 5 by Puff the magic wagon, on Flickr"><img src="https://farm3.staticflickr.com/2942/15354583552_6f2f6e6768_z.jpg" width="480" height="640" alt="tach 5"></a>
<a href="https://www.flickr.com/photos/65872230@N08/15168194870" title="tach 4 by Puff the magic wagon, on Flickr"><img src="https://farm3.staticflickr.com/2944/15168194870_08afe64340_z.jpg" width="640" height="480" alt="tach 4"></a>
cut the wire, pull it back through the fire wall fish it across the dash to close to you 12v+ source and your megasquirt in my case the glove box. connector up the wires to the relay like this (Remember Pink/white is tach out, notice that i use a solid pink wire as tach in from the ms 37db connector to make it easier to fingering this out when its all jammed into my glove box.)
<a href="https://www.flickr.com/photos/65872230@N08/15168388187" title="tach 19 by Puff the magic wagon, on Flickr"><img src="https://farm3.staticflickr.com/2942/15168388187_7288d83644_z.jpg" width="480" height="640" alt="tach 19"></a>
and there you heigh-ho the derry-ho your stock tach is working now