How I Failed to Install a Tachometer

dash tach

I figured I’d take my mind off the fact that I may not have a job in a few weeks and finally install the tach I pulled from a 244 in a VA junkyard this summer. While I love the big clock in the Volvo instrument panel, I’d also like to see what’s going on with the engine. Unfortunately I now have no clock, no tach, no odometer and no speedometer.

After consulting Dave Barton’s tach install post I realized I’d forgotten to pull the wiring harness that attaches the small clock to the tach from the junked brick. It’s obviously necessary to run the clock, but I think it might also close the electrical circuit for the tach.

dash

Using a 27mm deep socket wrench I pulled the steering wheel off and pulled out the instrument panel. This gave me a chance to also fix the broken trip odometer. Good thing, because the gas gauge doesn’t work and it’s crucial to know how many miles I’ve gone since the last fill up. Once I’m over 250 miles it puts me in risk of being stranded on the side of the road, with crying children and a sighing wife.

I used some compressed air to clean everything, then installed the tach. Somehow there were two prongs sticking out the back, instead of the one I’d seen in the how-to. To connect to left or right? I chose left. I plugged everything else in, mounted the panel, hooked up the battery, and now not only do I not have a clock, or a tach, but the speedometer and odometer don’t work. What a disaster. Looks like I’ll need to dig in again soon.

UPDATE: Fixed!

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4 thoughts on “How I Failed to Install a Tachometer

  1. Pingback: My Black Brick » Archives » Getting Power to the Dash, if not the Road

  2. James P 93 244

    Hello,
    I’ve enjoyed browsing your site and just stumbled on your tach install page. I also just picked up a large tach & small clock and am curious about you removing the steering wheel. My Bentley manual has warnings about removing the steering wheel because of the airbag. What did you do to remove the steering wheel and did you encounter any complications with the SRS system???
    Thanks!
    James

  3. DoctorJay

    I didn’t have any problems with the SRS, other than unspringing the coil, which I still need to fix.

    First you have to undo the screws behind the steering wheel. You have to have the key in the ignition so you can turn the wheel to get to them and not have it lock. Then you steer straight, pull the key, undo the battery terminal, then wait 2 minutes before taking off the airbag. Either the Bentley or Haynes manual said the bag has the ability to deploy for 30 seconds or so after the battery is cut off. If I remember correctly you can then pull the bag off and get to the gigantic, 27mm nut holding the steering wheel in place.

    By the way, pulling the wheel makes things much easier to access the panel. When I pulled the tach out of a 240 in the junkyard I didn’t take off the wheel and it was real tough.

  4. David

    I did the tach/clock swap last month. The Bentley book had me so freaked about the airbag blasting off in my face that I had no intention of removing the steering wheel, though I did disconnect the battery. But if I need to pull the cluster again, I’ll do it, because getting that brittle plastic box out of there with the wheel in place was a supreme pain in the ass.

    To my great surprise, everything worked afterwards. I need to pull it again at some point because all that jostling resulted in the lamp over the temp/fuel gauges burning out.

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