So it sounds like I can either use the 16 or the 8 amp fuse to give power to my tach, however, I'm concearned that if I go with the larger one like I'll think I'll have to and something goes wrong with the tach, the car might catch fire, go electronilally crazy or what have you. I thought that if the fuse was too strong then it might cause a fire when there is a problem, because it won't be able to blow? Also this most of this is the stockwire that came with the gugage, and it is much thinner then the stuff in the bigger fuses. Should I be comparing? Maybe you think I'm crazy, but I'm 19 and not an expert on cars. I just ask a lot of questions...in hope of some day being educated.

What would be wrong with wireing the tach to a fuse that is always hot? I guess it would be bad but not sure why? Probaby don't want to do it with the in tank fuel pump 8 amp one either? I don't want to be like the guy who was selling his 92 240 on ebay a while ago, because he installed a stereo and it caught fire. Not to cool!

Thanks for listening and explaining.

If you are worried about it put a small in-line fuse holder right after the fusebox with 5A fuse in it and run the wire to your tach from there.

Onkel Udo

You worry too much. Either size fuse will blow quickly if you accidentally create a short circuit. You wouldn't believe how many 25s and 15's I've blown in my wifes car due to a loose dome light... none came anywhere near melting or burning anything but the fuse.
The only hazard you have comes from UNFUSED circuits straight from the battery. That guy with the 240 radio surely had something like that... and it's stupid on his part. A friend did have a 740 sedan burn to the ground due to bad battery cables shorting together- again, unfused power.
There's no need for the tach to be on a circuit that is on all the time either; there are spare circuits in most 240s with proper capacity that turn on with the key. You really should spend $30 and get a good voltmeter- it will pay dividends on this and many other jobs.
--
Rob Bareiss, New London CT ::: '87 244DL/M47- 229K, 88 744GLE- 218K, 82 245T-181K Also responsible for the care and feeding of: 88 745GLE, 231K, 87 244DL, 239K, 88 245DL, 246K