Stereo power question - constant vs switched?

[AJMBLAZER]

Big Ugly, being a CUCV, didn't come with any ACC position for the ignition. The military didn't need it so there's basically just off, on, and start. Simpler and all they needed ya know?

I put a stereo in last year and used fuse taps to run the 12v switched and 12v constant power that it needed. Now the thing is I can't sit in my truck and listen to the stereo without either having the truck running or having to have it in the on position which then energizes the glow plugs.

Can I change the switched 12v power source to a constant 12v? I figure there's nothing preventing me from doing that but what issues would I have? I know I'd have to turn the radio off every time I was done using it but I keep it loud enough that shouldn't be a problem (diesel truck with no sound proofing). Would I loose my stations and such every time I turned the radio off...but I think that's what the existing constant 12v is for...right?

 

[AZ79K5Project]

The only issue is forgetting to turn it off. I had my system powered to always on while in college for the bonfire nights out in the forest.

The switched wire will never know that it's not wired through a switch. The constant battery wire maintains your station and clock settings.

 

[t89blazer]

You could possibly wire in a toggle switch so that you can power the radio on manually or turn the switch off and it would work normally. Where are you getting you switched power from now? The only problem I can see is that the toggle switch may back feed into the source of your switched power. Does this make sense?

 

[AJMBLAZER]

Vaguely.

I used NAPA single prong taps from the fuse block. I had a diagram of the CUCV fuse block and simply tapped into a 12v constant and a 12v switched.

Could I just replace the 12v switched source with a constant source?

 

[AZ79K5Project]

Yes - there's no need for a toggle switch unless you want to control multiple devices. The power switch on the stereo is all you need when connected to constant 12V.

 

[cdoggwsu]

Vaguely.

I used NAPA single prong taps from the fuse block. I had a diagram of the CUCV fuse block and simply tapped into a 12v constant and a 12v switched.

Could I just replace the 12v switched source with a constant source?

x2 on the constant source. On a side note, I just used those NAPA taps tonite and...is it just me or were those the flimsiest things you could imagine. I searched everywhere to find one of those "add a circuit" fuse taps and the NAPA one's were all I could find...

 

[AJMBLAZER]

Mine worked pretty good. Well...I did end up breaking one but that's my own damn fault.
Yours white?

I dunno about Washington but a year ago I couldn't find ANYTHING up here for this purpose. Luckily the local NAPA guru vaguely remembered these and dug around in his big NAPA catalog until he found them and then I got the last several in the warehouse down in Grand Rapids. Everybody else thought I was nuts or wanted one of those fuse piggy-back thingies that just slides in around an existing fuse.

 

[GNERGY]

I wanted to turn on the radio in my burb with out having to turn the key to accy. So I put a switch in ( for my switched 12v. ) at the bottom of the dash under the radio. Then when I turned it on the rest of the stuff that got power off that circuit turned on also. So I got a diode ( radio shack part # 276-1661 ) and put it in the circuit and it works perfact now. I like to play tunes while we're camping without leaving my keys in there.
Tarey

 

[t89blazer]

I wanted to turn on the radio in my burb with out having to turn the key to accy. So I put a switch in ( for my switched 12v. ) at the bottom of the dash under the radio. Then when I turned it on the rest of the stuff that got power off that circuit turned on also. So I got a diode ( radio shack part # 276-1661 ) and put it in the circuit and it works perfact now. I like to play tunes while we're camping without leaving my keys in there.
Tarey

This is what I was refering to. You could wire the switch so that when the switch is off, the radio would work normally ("On" on the column)or turn the switch on and it would bypass the column and you would have power to the radio without turning the ignition. That way you would not have to turn the radio off manually everytime you shut the truck off.

 

[colbystephens]

Big Ugly, being a CUCV, didn't come with any ACC position for the ignition. The military didn't need it so there's basically just off, on, and start. Simpler and all they needed ya know?

I put a stereo in last year and used fuse taps to run the 12v switched and 12v constant power that it needed. Now the thing is I can't sit in my truck and listen to the stereo without either having the truck running or having to have it in the on position which then energizes the glow plugs.

Can I change the switched 12v power source to a constant 12v? I figure there's nothing preventing me from doing that but what issues would I have? I know I'd have to turn the radio off every time I was done using it but I keep it loud enough that shouldn't be a problem (diesel truck with no sound proofing). Would I loose my stations and such every time I turned the radio off...but I think that's what the existing constant 12v is for...right?

another alternative is going to a manual glow plug set up. that's a real easy fix - and then you get to control 'em... which i personally like.

 

[AJMBLAZER]

Knock on wood...my glow plug system, and the entire electrical system, works just fine right now in full milspec trim.

One day when some of the milspec 24v systems start giving me trouble it'll be time to do the 12v conversion and then start simplifying the electrical system.

 

[dyeager535]

Since yours is an '86, doesn't it have the accessory terminals along the top of the fuse panel?

No idea if the "accessory" position on the ignition switch does anything on a CUCV, but that's the solution if it does.

 

[colbystephens]

Knock on wood...my glow plug system, and the entire electrical system, works just fine right now in full milspec trim.

One day when some of the milspec 24v systems start giving me trouble it'll be time to do the 12v conversion and then start simplifying the electrical system.

you lucky bastard!!

 

[AJMBLAZER]

Since yours is an '86, doesn't it have the accessory terminals along the top of the fuse panel?

Nope. I suspect that since it's a CUCV everything is 83-84 style and even though the vin says 1986 the truck is pretty much a standard '83 or '84 model. GM used up the parts pile and the military didn't have to have extra spares and more add ons to the TSM's.

No idea if the "accessory" position on the ignition switch does anything on a CUCV, but that's the solution if it does.

There is no accessory position. Off, on, and start.

 

[AJMBLAZER]

So I did it today. Ran a wire through the fire wall and over to the "out" stud on the 12v junction. Works great so far.


Random thought though...the radio is always on. Even when off the display is lit with the time displayed. How long would it sit like that before that teensy drain caused me trouble on the front battery (the one that powers the 12v stuff)?

 

[dyeager535]

I think it's enough to cause a potential problem, IF you don't drive it daily. Even then, to me any additional load on a non-deep cycle battery (and alternator) for charge/discharge, is a bad thing.

CUCV really adds some complexity in resolving this with no auxillary setting in the ignition. If you've got the "older" '81-91 fuse panel, it will still have accessory ports on it, they are just scattered around. You might check and see if GM did indeed use up old harnesses and those ports are live.

 

[AJMBLAZER]

I've got group 31 tractor/heavy truck batteries and I was under the impression they are deep cycle. Also damn big and heavy.

I think you are referring to the accessory ports that sort of look like a fuse slot only with space for one prong? If you are I then I do have a few of those distributed around the fuse block. Off the top of my head one is a constant 24v, one is constant 12v (and I have the radio and my cigarette lighter getting power from that through a double tap from NAPA), and two or three switched 12v spaces. I had the radio hooked up to one of those originally but there was my problem as while the memory was saved by the 12v constant the switched meant I had to turn the key to run to listen to it without the truck being on.

 

[dyeager535]

Damn diesels, I keep forgetting you don't want it in "run" with the engine off for long periods, correct?

I don't see a failsafe work around here unfortunately, if the above is the case. I wonder if the ignition switch is all wired up for a key that has accessory though? GM obviously did some weird stuff on these trucks, perhaps the ignition is wired up "right" and if you *could* turn the key to accessory, the fuse panel would work correctly. No clue how they stopped you from turning the key to accessory though, my guess would be the lock cylinder is different.

 

[cdoggwsu]

I dunno if the CUCV's are the same but on my '88 the radio will only come on if the key is switched all the way to "ON"..."ACC" won't do it. Do the glow plugs energize on the ACC position?

 

[AJMBLAZER]

Okay, lemme repeat myself...

THERE IS NO ACC POSITION.

OFF

flick it forward one

RUN/ON (this is when the dash lights and the wait to start light turn on)

flick it forward to the last stop

START

That's it. That's all any CUCV ever got and I suspect all the bare bones, no radio civy trucks too.
There is no ACC position like most older American vehicles where you twist the cylinder back towards you to engage it. Nothing like Japanese vehicles either where there's a position between OFF and RUN.




dyeager, correct, having it in run makes the glow plugs cycle on and off.

Someone over on SteelSoldiers has mentioned putting a toggle switch between the power and the radio. Making that switch do the work of the ACC position basically. Might even have a switch...