ostie13

I am installing a Tachometer in my 71 Toronado and when I was under the dash trying to find a place to attach the power wire I noticed that to the left of the fuse block,just in front of the E-brake was a place that had 8 metal prongs that you could attach wires to. Only one was pluged into it and the wire is red. To me it looks like a junction box.Can I plug my tachometer into it or am I way off base. I dont see anything in the 71 service Manual that showes anything about it but I am sure it is stock and not a

RandyS

You will want to check that this is a switched power location (has power when key is in run position). If it is, you can use it, if not, you will drain your battery.

MDchanic

One row of those terminals is hot all the time (not good for the tach), and the other row is switched with the ignition.

- Eric

ostie13

Should I put a fuse on the power wire and If so what size? Or does the junction block alredy have a fuse.?

RandyS

Yes, you can install an 'in-line' fuse holder on the power wire to your tach. Any size fuse you have handy will work as the tach will draw only minimal power.

ostie13

You were absolutly correct.One row is hot and the other row is Key powered.I hooked the power wire and the lite wire to the keyed side. I like the lite to come on to my tach on all the time. What would you attach to the hot side of that junction box.It has one plug already in it from the factory.

MDchanic

The power supply block is there for the connection of whatever electrical accessories are ordered with the car. Some work only when the key is on, others work all the time. For instance, the power seat works all the time, but the power windows work only when the key is on. The power windows are connected with their main power coming from the always-on side, controlled by a relay that is triggered from the ignition-on side.

Prior to 1971 (in full-size cars - '73, I believe, in midsize cars), accessories were connected to the single IGN, ACC, and BAT spade terminals in the fuse block, and each accessory had a plug with a female pigtail coming off of it that you could connect another accessory to. As time passed, especially in the big cars, people started ordering more and more accessories, which led to more and more spaghetti under the dash, so they came up with these power strips as a solution.

- Eric

ostie13

Ok then will a 5 or 10 watt fuse work then? Or would you put a bigger one in it.

MDchanic

I can't imagine a modern tach using more than an amp, so a 1 amp fuse should be fine, but 2 would be okay, too, and 5 shouldn't hurt anything, as Randy said.

Certainly there's no reason to go any bigger. The mental picture of a tachometer that needed a 20 amp fuse made me laugh out loud.

- Eric