Fuse Block Question - Where to pull power?

[cmroles]

I am looking to add a couple of circuits to run a 12V accessory socket in the cigarette lighter position, and to power a CB. I don't anticipate needing a huge current-handling capacity.

I checked the fuse block and found a couple of "individual" terminals that have 12V Key On / 0V Key Off

What I was thinking of doing was running a wire for 12V to one of these terminals. Add an inline fuse and crimp a 1/4" blade on the end of the wire. Just plug the blade into this socket to tap the 12V and then just use the dash / chassis on the accessory end for ground.

Will this work, or is it a bad idea? From the -20 it looks like these terminals may be tied in with part of the ignition circuit, but its hard to tell from the pictures / diagrams.

Also - anybody have any info on what they are originally for? They don't appear to be regular slots for a blade-type fuse, just a single terminal each with 12V...

 

[killer_kricket]

Those are +12v accessory slots. They are linked to the ignition. This would be for items like the yellow wire in a cd deck wiring or items you want power to only when the ignition is in the acc or run position. I have my second gauge cluster wiring attached to one for its backlighting.

For solid +12v there is a similar slot next to the 5amp fuse on the op that is on regardless of the ignition.

Here is a great diagram:
http://www.steelsoldiers.com/cucv/20600-faq-thread-cucvs-2.html#post233428

 

[cmroles]

Those are +12v accessory slots. They are linked to the ignition. This would be for items like the yellow wire in a cd deck wiring or items you want power to only when the ignition is in the acc or run position. I have my second gauge cluster wiring attached to one for its backlighting.

So it's safe to assume that it would be a good place to pull power? Since these aren't normal fuse sockets, how would the factory wiring be setup? I just don't want to overdraw the circuit they come from and smoke the wiring...

What type of setup did you use for your gauge lighting?

 

[killer_kricket]

I used a spade connector with an inline fuse. I also connected it to the light switch, (pull knob) so it only comes on when they are on.

I really don't think there are any factory setups, rather these are extra sockets for aftermarket systems. They are just enabling you to add new systems in a professional and visually appealing way without heavy modification.

The Gauges were an autometer kit, with engine temp, voltage and oil pressure. Three very important devices for heavy off-road use. (1"1/2)

 

[cmroles]

I used a spade connector with an inline fuse. I also connected it to the light switch, (pull knob) so it only comes on when they are on.

I really don't think there are any factory setups, rather these are extra sockets for aftermarket systems. They are just enabling you to add new systems in a professional and visually appealing way without heavy modification.

The Gauges were an autometer kit, with engine temp, voltage and oil pressure. Three very important devices for heavy off-road use. (1"1/2)

Did you just plug the spade connector into the "front" of the fuse- block (side the fuses plug into? Also, how did you also tap off of the light switch? Automotive electrical is a little new to me so I'm looking for all the ideas I can get.

One more thing: How / where did you mount your gauges? I've been looking at different setups trying to figure out where is best.

 

[Hogg]

I ran a heavy guage wire from the 12V batt (front) into the cab and put in a separate small fuse box to run accsessories on and mounted it on the pass side kick panel that way I dont have to worry about frying the original 25 yr old fuse block... Works great, I run a phone booster with amp and antenna, and a Highliner stereo with four speakers in it and have had no problems. Im sure your idea will work fine, just a suggetion

 

[Warthog]

The three empty 12v spade connectors you circled are controled by the ignition fuse that I have circled

 

[cmroles]

The three empty 12v spade connectors you circled are controled by the ignition fuse that I have circled

Is it safe to fun extra accessories off these? Like I said I'm mainly interested in running a CB and a 12V accessory plug. I don't anticipate ever pulling more than ~10A tops.

I intend to use an inline fuse on each line to prevent "mishaps".

 

[Warthog]

It's fine since the ports are controled by the 20a fuse.

 

[Barrman]

Yes it is safe. In line fuses are a great idea as long as you make them in a location you can get to once everything is installed and the truck is going down the road. Putting the fuse up behind the lighter location is just asking for it to go out on a cold rainy night when your cell phone is dead and you are 100 miles from a light source.

 

[dunedigger]

At trips to the scrap yard I have found a lot of factory connectors pluged into the ignition slots on civi trucks in the same era. I'll cut 5" or so of wire off and unplug them. Most of the time I try to pay the yard says just take them. I like to solder my fuse holder right to that wire. It has a little clip that won't let it fall out of the fuse block.

 

[cmroles]

OK...one more question about this.....

I wired into one of those "accessory" plugs that I circled in the attached picture. I ran wire (with an inline fuse) from the Fuse Block to the lighter position, and then ran a ground wire from a chassis ground to the lighter position.

I decided to test the wiring before plugging in the socket. If I measure resistance between positive and ground with the ignition completely OFF I find a short (~1ohm) to ground, with ignition ON I find 12.5V.

The question: why the heck is it shorting to ground with the ignition off? Is this normal behavior for that circuit? I would expect to measure 12V ignition ON and an OPEN with ignition OFF. Am I missing something, or is there a very funky wiring problem here?

 

[wired1000]

Any recommendations for a place to ground under the dash?

 

[wired1000]

Nevermind, found this awesome post from Warthog. THANKS http://www.steelsoldiers.com/cucv/50551-cucv-switches-diodes-relays.html

 

[av8rnik]

I used a spade connector with an inline fuse. I also connected it to the light switch, (pull knob) so it only comes on when they are on.

killer_kricket, do you have a picture of the setup in the fuse block? Also, where did you tie into to connect it to the light switch? I am installing an autometer tach.

 

[MarcusOReallyus]

I ran a heavy guage wire from the 12V batt (front) into the cab and put in a separate small fuse box to run accsessories on and mounted it on the pass side kick panel that way I dont have to worry about frying the original 25 yr old fuse block... Works great, I run a phone booster with amp and antenna, and a Highliner stereo with four speakers in it and have had no problems. Im sure your idea will work fine, just a suggetion

This is a MUCH better choice than tapping into the fuse block. Our trucks are old, and the wiring is tired. I strongly suggest doing it this way, and then if you need something that is switched on the key, add a relay. Trigger the relay with a tap into the fuse block, and feed power from your new circuit.

 

[av8rnik]

Why not run the wire from the 12V block on the fire wall in the engine compartment, the one on the driver side near the GP relay?

 

[Keith_J]

This is a MUCH better choice than tapping into the fuse block. Our trucks are old, and the wiring is tired. I strongly suggest doing it this way, and then if you need something that is switched on the key, add a relay. Trigger the relay with a tap into the fuse block, and feed power from your new circuit.

I did just that but instead of running off the front battery, the relay switches the back. I had to use another line at 12 volts for the negative to get 12 volts at the accessory outlet. Yes, it works fine. Only thing is the negative part is 12 volts with respect to ground, the outlet I used has two wires and isn't grounded.

This also powers the back-up camera and the blower/relay for the air conditioning. This balances the load on the alternators.

 

[MarcusOReallyus]

I wouldn't recommend that approach for anyone who is not pretty well expert in electrical stuff. You know enough to get away with it, Keith, but a lot of folks could find themselves in trouble with that approach. Having a "ground" that is hot, and a hot that is hotter, could cause a mite of confusion!

And think of the fun if they sell the truck like that to someone who doesn't know the setup!

Why not run the wire from the 12V block on the fire wall in the engine compartment, the one on the driver side near the GP relay?

That would work. I think the ideal setup is to tap the front battery over to a new fuse block on the fender, and go from there, but running from the existing 12V block is just fine, IMO.

Depends on how much juice you expect to need, of course.

 

[soulbrojosh]

i am not that familiar with auto electrical...would a new fuse block, run off of the front battery, need to be grounded? and if so, where should it be grounded to?