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Unread 01-02-2014, 06:09 PM   #1
Jester77
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Not enough 12V Switched sources

I'm in the middle of wiring up all the new electronic Autometer gauges for the CJ-7 and I've quickly run out of 12V Switched sources to supply the gauges power. Actually, I only have one left and I need to power three more gauges.

Would it hurt if I powered all three of these gauges from the one 12V switched source I have left?

Any thoughts or suggestions would be welcomed.

Jester

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Unread 01-02-2014, 06:16 PM   #2
UBERK
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Quote:
Originally Posted by Jester77 View Post
I'm in the middle of wiring up all the new electronic Autometer gauges for the CJ-7 and I've quickly run out of 12V Switched sources to supply the gauges power. Actually, I only have one left and I need to power three more gauges.

Would it hurt if I powered all three of these gauges from the one 12V switched source I have left?

Any thoughts or suggestions would be welcomed.

Jester
Can you run 12V stwtched to one of these and just stick it where ever it works best....

http://www.vteworld.com/content/elec...ml/ttb/ttb.php



http://www.vteworld.com/content/elec...nt/10point.php

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Unread 01-02-2014, 06:58 PM   #3
BagusJeep
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Very hard to say definitely without knowing what changes you have made to the standard CJ wiring or what state the wiring is in or what the draw is on those new instruments.

I will assume it is a standard 1985 wiring system with standard fuse box. (Diagram below).

All the instrument panel gauges should be wired through the IGN LPS 10 Amp fuse. This feeds the 16 gauge Red wires to the dash that are live in Run and Start but not ACCY. (Not to be confused with the Cigar Lighter that is also Red from the ACC fuse but is live in Run and ACCY only). If they all go through this fuse the next owner will not be cursing the PO (you).

What you would do is either splice into the Red wire to feed other gauges (factory) or join at the terminal on the back of the first gauge, take it to the second gauge etc. There are connectors that allow you to do this or put two wires in one connector. Jeephammer had a Wiring 101 page that explained the options pretty well.

If the instruments are not exceptionally high draw you should be fine to power three gauges from where only one was before, but check the current draw against the length of wire and carrying capacity of a 16 gauge wire.

UBERK's solution is fine but needs a cover. It would make a convenient ground marshalling point but with only a few instruments to power is not as efficient as splicing the wires.
84-86_fuseblock.jpg  
84-86fuseboxsch-copy-2-.jpg

82fusebox.jpg

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Unread 01-02-2014, 07:59 PM   #4
Jester77
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The original CJ-7 wiring harness is intact....after I cleaned up a bunch of monstrosities from the PO.

I've added seven of the Autometer Phantom II gauges to a custom Double D dash. I've added quick disconnect plugs for each of the gauges, which will help me remove/replace for future failures/upgrades. These connectors are made by Tyco Electronics (part numbers available upon request).

Although this looks like a mess of spaghetti, it's not. You can see the quick disconnects (black plugs) I've added to each gauge in this picture. I apologize for these pics, they're from a stupid iPhone. I'll straighten out, clean up, and zip tie up this mess when I'm done with the wiring.

dash1.jpg

I've only got two more gauges to go -- the Tach and the Speedo.

For example, here is a pic of the tachometer quick disconnect plug.
dash2.jpg

There's only four wires that go to the tach

1 = +12V Lighting (white)
2 = Ground (black)
3 = SIG to - side of coil (blue)
4 = +12V Switched/Ignition (red)

These four wires will come from the original Jeep's wiring harness (save for the blue coil wire, I just ran a blue one myself through the firewall to the coil) and I will solder pins that fit into the back of this plug to allow for the quick disconnect.

Reason I asks this is because I wasn't sure if the load of these three gauges (speedo, tach, and the GPS Speedometer Interface) would be too much for one switched 12V source. Looks like it's not. Now looking at the wiring diagram I have of a 1985 CJ-7, it looks like there are a lot of "splices" that route 12V power to various components.

I'm using 16 AWG for all the new wiring and I have crimped, soldered, and heat shrunk all the connections up to this point. Also, I'm adding a 4A, 3AG inline fuse for every gauge on the 12V Switched input. I would rather crimp, solder, and heat shrink all the connections and not have any open 12V sources hanging out there...too easy to short something out otherwise.

It looks like splicing is the best option at this point. All your input is greatly appreciated!

Jester

P.S. Ignore those wire nuts. They are temporary to test the 12V source for the LED lights behind the gauges. Those will definitely be removed prior to buttoning this up!
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Unread 01-02-2014, 10:45 PM   #5
BagusJeep
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Quote:
Originally Posted by Jester77 View Post
The original CJ-7 wiring harness is intact....after I cleaned up a bunch of monstrosities from the PO.

hahaha, looks like you are not going to be the monstrous "PO" in the future, nice work.
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Unread 01-03-2014, 01:28 AM   #6
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Man, those DD dashes are nice! I would say if the guage draw for all seven is less than 3 or 4 amp (50 watts or less) and your system is in good shape, you could tap from the one switched source and daisy what you can and single out what needs clean inputs.

Nice work there.

WSS
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Unread 01-03-2014, 09:14 AM   #7
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One easy way is to use a relay. You can mount it next to your gauges, then wire all your power leads to it. Since it uses a single battery lead and a single small gauge wire from your switched source to activate it, you can consolidate all of your wiring at the gauges with a minimum of mess. Since it uses very little voltage to activate, you can tap into just about any switched source with very little draw.
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Unread 01-03-2014, 09:25 PM   #8
Jester77
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Quote:
Originally Posted by jeepdaddy2000 View Post
One easy way is to use a relay. You can mount it next to your gauges, then wire all your power leads to it. Since it uses a single battery lead and a single small gauge wire from your switched source to activate it, you can consolidate all of your wiring at the gauges with a minimum of mess. Since it uses very little voltage to activate, you can tap into just about any switched source with very little draw.
This idea has me intrigued. However, on a single Bosch-type relay, isn't there just one lead that supplies the 12V DC power to the accessories (in my case gauges)? I still need 3 sources to feed the remaining three gauges. Do I run all three components to pin 87?
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Unread 01-03-2014, 09:29 PM   #9
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Quote:
Originally Posted by Jester77 View Post
This idea has me intrigued. However, on a single Bosch-type relay, isn't there just one lead that supplies the 12V DC power to the accessories (in my case gauges)? I still need 3 sources to feed the remaining three gauges. Do I run all three components to pin 87?
Daisy chain if you can. Pick up the main and use the the hot off the gauge to go to the next gauge and so on.
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Unread 01-04-2014, 12:10 AM   #10
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Quote:
Originally Posted by Jester77 View Post
This idea has me intrigued. However, on a single Bosch-type relay, isn't there just one lead that supplies the 12V DC power to the accessories (in my case gauges)? I still need 3 sources to feed the remaining three gauges. Do I run all three components to pin 87?
splice all the gauge leads together and then to the single 12 post (87).
You can splice in a fuse as well if you think you need it.
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Unread 01-04-2014, 06:39 AM   #11
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Although I have never used a relay, I am familiar with how they work. Take a look at this schematic and tell me which one you think is the best design/most efficient?

relay.png

I like the idea of using a relay.
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Unread 01-04-2014, 08:04 AM   #12
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Jester,
I would use the #2 schematic for the simplicity. If you lose the fuse, you lose all three gauges, which might make the trouble shooting a little tougher, but the relay and wiring are protected from the source amperage. The relay will handle much more amperage than your wiring and gauges will stand. I'd put the safety valve(fuse) before the relay. God bless.
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Unread 01-04-2014, 08:24 AM   #13
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Originally Posted by jeepdaddy2000 View Post
One easy way is to use a relay. You can mount it next to your gauges, then wire all your power leads to it. Since it uses a single battery lead and a single small gauge wire from your switched source to activate it, you can consolidate all of your wiring at the gauges with a minimum of mess. Since it uses very little voltage to activate, you can tap into just about any switched source with very little draw.
Agreed. Build for the future, feed a terminal strip or fuse block from this relay and have a bunch of safe connection points for future projects.

Splicing is the quick and easy way, but in the long run it invites troubles
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Unread 01-04-2014, 10:17 AM   #14
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I too would choose #2. Be sure to place the fuse as close to the battery (main 12V connection point) on the circuit as possible since the most probable place for a short to occur is between the battery and the relay.
I like sealed spade style fuses for outside use

and open ended spade for inside the cab.



Quote:
Agreed. Build for the future, feed a terminal strip or fuse block from this relay and have a bunch of safe connection points for future projects.

Splicing is the quick and easy way, but in the long run it invites troubles
I tend to disagree with your view of splicing. Splicing has been routinely used by OEM manufactures in their looms with no issues, and if done properly, will last the life of the vehicle.
While terminal strips have there uses, unless it is easily accessible, I tend to steer away from them. I have found that corrosion has a tendency to collect on the terminal ends and (cheap) connectors have a bad habit of coming loose. I was rather heavily involved with VW's for a time and their stock fuse panel was basically a fused terminal strip. There was nothing but trouble with them across the board and they pretty much cured me of their use. For me, I would rather use an insulated stud to connect multiple leads to a power source (just a personal view).

Last edited by jeepdaddy2000; 01-04-2014 at 10:18 AM.. Reason: lost a picture
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Unread 01-05-2014, 01:03 PM   #15
Jester77
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This is what I decided to go with.

gauges.png

Anybody see anything wrong with this setup?

Jester
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