Hi guys.

I intend on adding an after market tach to my car. Its a 244 2.3L automatic. I dont want to remove the stock clock from the instrument cluster or add any drills or anything of the sort. I am trying to keep everything as original as possible.

I just want to add the tach and see how my engine is idling and at points it shifts that's all - after that I will be removing it.

The aftermarket came with 4 wires:
Red- ignition power
Black- ground
White- illumination power
Green- tach wire

Now, the 240 already has a tach wire behind the instrument cluster but is not used since I have the clock. Any advice on how to get this hooked up? I couldnt find anything on the internet - so maybe this might help others who want to do something similar. Thanks!

 

the red/white(*) striped wire that goes nowhere tucked in behind the instrument panel is the tach wire. it comes from the coil pin 1

fuse 16 is on the park lights circuit, so you could use that for your illumination. (green wire) (**)

fuse 13 provides power to the instrument panels stuff, so thats probably a OK place to get the 'ignition power' (blue-red wire)



(*) its red/white on newer 240's, you didn't say what year you have. I grabbed a 1980 greenbook, it shows it as a black wire, either way, this comes right off the coil pin 1.

(**) on the fuse panel, there's three rows of spade lugs to the right of the fuses. the one farthest from you (closest to the front of hte car and/or the right) is the 'input' to the fuses, and the middle and leftmost rows are the 'outputs' of the fuses.

 

Thanks for the advice Pierce! I just want to get a hang of everything before I cut any wires. Its a 1991 base trim. Just so that I understand -

1. Connect tach wire of aftermarket (green wire - tach) can be connected to Volvo tach wire (red/white - car).
2. Connect the illumination wire of the aftermarket (white wire - tach) to the wire of fuse 16.
3. Connect the ignition wire of aftermarket (red wire - tach) to the wire of fuse 13
4. Connect the ground wire of the aftermarket (black wire- tach) to the ground bolt just behind the center console where all the stuff gets grounded

Is that correct? Sorry if some of these sound dumb - I am not the best with electrical stuff and just want to make sure that I am doing the right thing.

 

yeah, exactly.

those fuse panel connections, there should be spare spade lug connectors in the middle or leftmost row just right of the appropriate fuses, so you can just crimp a spade lug onto your wire and press it on to the spade on the fuse block.

 

Perfect! I should be getting the tach tomorrow or day after. I shall put it and post back here on how it went.

 

as always, disconnect the battery ground (-) lead before doing any electrical work.

 

So I went ahead and put it in finally. Turns out it was much easier than what I thought - took me about 35 mins.

I connected the signal wire of the tach to the pre-wired cable that was already there. The positive wire was connected to the additional spot on fuse 13. You might need to take the under knee dash panel off so that the new wire can be concealed. I then took the center console off and connected the ground wire to the screw that hols all the other ground wires (its the screw behind the AC on/off switch).

Very easy.