ELECTRICITY 101: INSTALLING GAUGES:

[Stewart G Griffin]

i'm getting ready to install the tach/speedo thing.  i have installed tachs before---after watching someone, but it was sloppy and probably not done right.  In fact, the last gauge i installed--a voltmeter on another car, i would actually unplug it from the fuse box everytime i parked because i was afraid of a possible fire.

So this time, the goals are:
1) To install it right---no hack jobs, no sloppy work. Make it look as close as possible to a factory installation.


2) Safety.  We don't want to damage the truck's other wiring or possibly start a fire.

The other thing is, i know next to jack about electricity so if you'll please dumb it down for me---as in real dumb.  Pretend that i'm 5 yrs old or something, and you have to explain to me how to fix my truck.  Thanks.
The truck is an 83 C-10 and the photos below are the actual fuse box.

So let's say i plug a blade-type connector into the "a" jacks for 12V power only when the key is on:



a) Are these "a" terminals fused?  If not, can i put an inline fuse after the terminal and before the tach, say 2amps or 5 amps and it will be ok?

b) i would actually prefer to tap into a pre-existing 12V key on only wire because i think i can get a cleaner installation that way using one of these: http://www.posi-lock.com/posiplug.html
Is there a way to find out which wire goes to which circuit or would i need a service manual or a heims?

If not, i would be willing to settle with using a terminal on the fuse box;  i think i can make a decent connection with the wire and the blade type terminal connector by using heat shrink wrap after crimping the terminal down.

c) i will need a source to dim the gauge at night (i'm planning on using a digital tach).  So, in other words, whenever the lights are turned on.  Is "b" the right terminal.  The lettering has rubbed off.

d) ground should not be a problem as there are plenty of screws at the bottom of the dash.  However, do you know where the factory grounded the gauges?

e) As far as plugging into the "tach" terminal in the HEI cap, i think i can handle that;  i know jegs/summit sell a lead and connector that plugs right in for about $6 and i can just make a posilock connection from the wire to the plug lead.

[Redneckchevy]

correct me if im wrong but i did the same install...For lighting i tappes in to the lps with a blade connector..And for Ign i tapped into the ign with a blade connector for ground i tapped into the ground with a female connector above the e brake....Now this is the part im not 100% sure about if u tap into the fuse block ur tapping on to a fused link..So if ur tach would mess up it would blow out the interior light fuse and so on? there are alot of post i made on this same subject if u look hard enugh

[werewolfx13]

I'd run an inline fuse for the ign hot..If you use regular "blade type" connector, don't just crimp it, solder it, it takes 10 seconds and gives you a good, strong mechanical and electrical bond, and reduces corrosion. I use a propane plumbing torch and 40/60 rosin core solder for most of my rough soldering like that. Crimp the connection on, light the torch, adjust the flame down to 3" overall, put the very end of the terminal in the flame, just infront of the hottest/bluest part of the flame for about 3 seconds, take it out, and touch the solder to the tiny bit of wire sticking out of the crimp connection. Let it cool about 30 seconds, slip your heatshrink up far enough to cover the fresh solder joint, but not so far as to interfere with the connection. I like to use the terminals that have the insulators on them already, and then cut/pull off the insulator.

[Captkaos]

What kind of gauges?  They should have instructions/requirements with them.

[Stewart G Griffin]

i'm probably going to go with the cyberdyne unit:
http://www.jegs.com/i/Cyberdyne/280/C270E351N/10002/-1

Or the autometer:
http://www.autometer.com/cat_gaugedetail.aspx?gid=3661&sid=66

i need digital because i need exact precision because i'm trying to calculate mpg.  My 73-87 "project" is a little different from everyone else's because my goal is maximum mpg, economy and frugality. Not speed    or looks.

i understand the basic concepts behind the instructions, but i wanted to do it right this time;  For example, if i use the "a" terminals and they weren't fused, it would probably not be a good idea to run the gauge with out using an inline fuse?

[Captkaos]

Are you getting all new gauges or just the Speedo and Tach?  If you are, we have Dakota Gauges for $511 in the catalog.

[Stewart G Griffin]

i think i'm going to go with just the speedo/tach at this time.  The dakota console is nice at a good price though.

Don't worry;  i'll probably buy something soon.  Probably the x-pipe assembly.  And very likely interior pieces, carpet etc.;  Remember i've got a custom deluxe---the cab is literally a metal box inside.

[Captkaos]

I'm not pushing you to buy anything from me, just sharing info.  I would like it if members supported the board with purchases as that is why I have the site, but...

[Stewart G Griffin]

UPDATE:

i've found out that "b" is the terminal for "Lamps" or "LPS."  So, i will probably use this for the dimmer function for the gauge.  Conventional gauges would use this for lighting at night whenever the lights are turned on.   Since my tach is digital, this would dim the gauge whenever the lights are turned on (presumably at night).

Should i also fuse this connection?