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Have a look at my fuse block with me real quick...

Craig Artzner

Craig Artzner

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1973 Chevy Blazer

Ok I don't have a 12V test light handy so I figured someone one here would know for sure. I'm wiring in my new mp3 player and need to provide it with an "always hot" wire in order to run the clock, save presets, etc. Since my Blazer has never had any stereo except the stock AM pushbutton radio with no clock, there is no wire readily available for this purpose.

The white arrow represents what I think would be an "always hot" connection (BAT.). It even has an extra unused wire coming off the plug (it's the wire that the white arrow actually points on). This is what I think I'm looking for.

The red arrow is what appears to be the accessory wire (power only when key is in "run" or turned backwards).

Am I right? School me or make fun of me if I'm not.

FuseBlock-2-21-07.jpg
 
This is why they make voltmeters. :) (or test light)

Unless someone can say with authority you are correct, never assume with wiring. I can look at your picture and just as easily say that the white arrow is simply a straight battery voltage (hot always) wire with NO fuse or circuit breaker protecting it, while the red arrow is also battery voltage but fused for accessories. Could be right, could be wrong, but I can see it being wired that way. Enough questions remain that I wouldn't assume. :)

Not attempting to be combative, just get/make a test light and see whats what there.
 
Who needs a test light? all you need is a light bulb, 2 pieces of wire, and some tape.

Grab an interior dome light bulb, tail light bulb, crap even a spare christmas light bulb. Hook one side to ground, test with teh other.
 
dhcomp said:
Who needs a test light? all you need is a light bulb, 2 pieces of wire, and some tape.

Grab an interior dome light bulb, tail light bulb, crap even a spare christmas light bulb. Hook one side to ground, test with teh other.
Click to expand...
That sounds easy enough. I may just try that tomorrow.
 
I like the dash and marker bulbs (198's or 164's) because you can bend the wires out, and solder to them.
 
If you have someone to hold the bulb and your aligator clips, the courtesy light right under the dash is normally the one i reach for......quick and easy.
 
I would say use the test light and be correct .

I could also say since it says "fused" above it , and the arrow says "acc" that that is a keyed on connection , and be correct .

I could also say the one next to it with "bat" above it is always hot , and be correct .

I do know mine always worked like that , and I have owned ( and still own ) both styles of fyse box , glass and flat fuse .
 
One beautiful thing that GM did was they kept their wire color codes consistent. Here is the breakdown:

Red = Unfused battery
Orange = Fused battery
Brown = Accessory
Pink = Ignition
Purple = Start signal
Gray = Illumination (dash lights/gauges etc)

That should cover anything you would need for your install. These colors hold true anywhere you find them in the truck, so if you find an orange wire in your roof, you know it is fused battery. That does not mean that they all come from the same fuse, just that they are fused battery or ignition etc.
I'm not sure about new vehicles, but I know until about '95ish these rules hold true.
--funny side note-- I was putting some aftermarket speakers in my '93 S10 and I couldn't find my service manual to figure out which wire was (+) or (-) for the speakers, but I did have the manual for my '79 Oldsmobile. Looked up the speaker schematic and wouldn't you know it, they still used the same color wires.
 
Doood, just to reiterate, buy a test light!

Heck, they practically give away those little cheesy ones.. A fair one will be less then $10...

#1 thing you need to do electrical, end of story...
 
Craig,

I have to agree that a test light is a good idea. You can get a cheapie for about $2 at the parts store. Bet eventually it will make you scream and you'll go buy a good one. I think I spent $15 or so on mine, and I'm much happier now:

My light.

Here's another way to get an 'always hot' wire. In my '74 I was pinched for time and didn't have a test light so.... I checked to make sure my ciarette lighter worked. The lighter is always hot and is fused.

I'm not really supporting this type of vehicle wiring. BUT, if you wanted a definite 'always hot' and 'fused' wire without using a test light... that lighter is a given.

Do with this information what you will.

-Ben
 
Craig,

I was just thinking some more about this. Can you take a picture for us of your whole fuse block. I'm pretty sure on my '74 it has a couple posts that you could push a spade connector onto. I even think they were marked. (Might have been 'acc' though, which wouldn't help you)...

Good Luck
 
Harbor freight has some really cheap ones $ and believe it or not the quality of them isnt bad either.
 
This is a stupid question, but why does that test light only have one terminal?

Doesn't it need a hot and ground connected? Ive never used a test light before, just cheap DMM's and circuit testers ive made.
 
OK I just bought me a test light today at work and a length of 18 gauge yellow wire. I'm going home tonight to finish this thing. I couldn't pass up the test light, my price at work gets it to me at less than $3 :D
 
BigBen said:
Craig,

I was just thinking some more about this. Can you take a picture for us of your whole fuse block. I'm pretty sure on my '74 it has a couple posts that you could push a spade connector onto. I even think they were marked. (Might have been 'acc' though, which wouldn't help you)...

Good Luck
Click to expand...

The two yellow wires in the picture (white arrow) are free to be used, the ends are out of sight but they have male spade terminals on the ends. I'm too lazy tonight :D to go out to the garage and have at it so this weekend sometime I'll nail it down.

My carpool buddy's stupid Ferd F250 took a crap and wouldn't start, causing me to get home way later than usual tonight.
 
Craig Artzner said:
The pointer on one end (+) and the alligator clip one the other end (-)(at the end of the wire)...
Click to expand...


duh, thats what i thought. Thanks!
 
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