[Ed Snyder]

The Sun tachometer in Dad's old one ton Suburban stopped working many years ago. I finally got motivated enough to troubleshoot it, and learned why Dad never bothered with it. First I had to lie under the front end to scrape undercoating off the bolt heads holding the grille on. After removing the grille, I had to remove the "wings" on either side of the core support too. The Sun tach was a dealer-installed option, so I don't know why they decided to hide the sending unit behind the grille.

After removing the sending unit and opening it up, I saw just what I was expecting -- lots of corrosion at both ends of the original mercury battery. After scraping off as much as I could, I installed a new AA battery as was suggested in an old post to the forum. However, after reinstalling the sending unit and starting the engine, I found that the tach still doesn't work.

So now I'm asking for suggestions on what to try next. I know replacing the Sun tach with a new one from Datcon or Isspro would be the easiest fix, but I'd like to preserve the original installation if possible. I seem to remember posts to the forum about converting the Sun tach to eliminate the remote sending unit, but haven't tried finding that yet.

See attached photos.