Hello,

Sorry, I've currently got another thread running about trying to fix my temp gauge, but I'm also trying to get my tach working. I mentioned it briefly in that thread, but I thought I'd raise the query separately as they (probably?!) aren't related.

My tach over-reads a little. It idles about 3k, and probably overheads by 2-3 times the actual rpm. I'm not entirely sure as I've not yet driven the car properly. However, the tach doesn't simply peg to the top on start up.

I've taken the tach out of the car, with the intention of soldering 200Kohm (or as near to 192 as I can get) resistors across the 'R4' connection as instructed in this thread:

https://www.thirdgen.org/forums/elec...oeter-fix.html

But something's puzzling me. When I measured the existing resistance across R4 (pins 4 & 10) on my tach, it read as a completely open circuit. I checked and double checked that I was measuring the right connections, and R4 definitely read as an open circuit. I thought that tachs with an open R4 circuit always pegged out the tachometer, whereas mine only over-reads?

I was all ready to wade in with my soldering iron, and now I'm wondering if I'm missing something. Should I just fix the resistors across R4, as the resistance clearly needs to be there… or should I be fixing something else?

Any help or advice is welcome!

 

Hello,

Does anyone have any suggestions on this? I'll probably go ahead, take a deep breath and make the repair, but it would be nice to have a little reassurance I'm on the right track before I go and ruin my only tach!

Cheers,

Neil

 

 

Thanks for the reassurance!

I've just bought myself a temperature-controlled soldering station, a set of helping hands, a solder sucker and some mini tools. I've also pulled a couple of old PCBs out of a derelict Rover that's sitting on the driveway. So hopefully I've got the gear I need and something to practice on before I take the plunge on the tach itself!