Keeping my original amp gauge

[Russell Ashley]

That was a very cool tip on changing your original amp gauge to a volt meter by Ogre. It was another good example of the ingenuity shown here on the forum. I did mine a little differently and thought I show what I did. I like the look of the original panel so I'm keeping it original, and I'd prefer an amp guage to a voltmeter. The original amp guage is a lot more sturdy that some might think. The current does not pass through any meter windings like the gas gauge, but rather through a brass framework and the hand is deflected by the electrical field around the frame. Here's a pic of the rear of the gauge showing the brass frame that I mentioned. In a parallel circuit the current is divided among the conductors. I added a jumper to two of the posts on the rear of the gauge to divide the current that the gauge actually reads so as not to peg the hand. The second pic shows the jumper. I'm using a GM 10SI alternator and so far it works just as I hoped. I did this back in October and have not had any ill effects from it. The hand acts just like it was designed to do, and goes most of the way to the right when first started and then drops back to slightly to the right side of the middle.
The temp gauge wasn't hooked up yet in the last pic but is now and works fine.

[SHORTDOG99]

Can you post a closer shot of just the jumper on that amp gauge? I am re-wiring my Suburban and i am looking to do the same thing as i want to keep the original gauges and look. Thanks.

[azsnow]

It looks to me as if you just added the jumper, but what else and to what side is connected to it?

[Russell Ashley]

In the pic the cluster is obviously not in the truck so the wires from the wiring harness are not shown. There are several male tabs on the back of the gauge and you put the jumper across the gauge using two of the un-used tabs. If your truck still has the original wiring and it's in good condition you only have to add the jumper. Be aware that the original wire was #14 which is typically good for up to about 40 amps. I'm using an EZ Wire harness with a #12 main wire. If you are adding a sound system or something else that requires an extreme amount of power you would need to accomodate that. All of the charging current plus accessory current will pass through the main wire and through the gauge and there is a limit to how much the gauge will stand even with the jumper wire splitting the current.

[Maximus]

thanks for the pics, and just to clarify, your EZ Harness was designed to use a volt meter right?
So instead you just ran the alternator power wire from the fuse block strait to the amp gauge, and then from the amp gauge to the alternator?
Or did you wire it a different way?

I will most likely be modifying my gauge to work with the volt meter since it (the EZ harness) is already wired for a volt meter and I already ran all of my wiring under my dash, but I want to know how you hooked yours up just in case...

[SHORTDOG99]

Same here! I already ran all my wires but want to keep the stock gauges...what do i do?

[_Ogre]

oh, now you tell me...

kidding and thanks for the kudos on the amp-to-volt-gauge mod,
i'm surprised it was an easy fix, as easy as just jumper out

i learned a lot about automotive wiring from madelectrical.com, he suggest bypassing everything.
but his diagram also shows how to hook up the amp gauge properly for those interested.

ezwire has 2 methods of hooking up the alternator; low amp goes thru the fuse panel and hi amp bypasses straight to the starter.
i used the 10ga ezwire alternator bypass wire that left me with a dead amp gauge and thought i'd try the volt gauge mod.

everyone that is working on truck wiring should read thru all the mad electrical tech tips section

maximus: i used ezwire. i don't remember a specific volt gauge wire.
i used the instrument wire to feed the gas, temp and volt gauges, since they all are fed hot and go to ground thru the sending unit.

[Russell Ashley]

Originally Posted by Maximus

thanks for the pics, and just to clarify, your EZ Harness was designed to use a volt meter right?
So instead you just ran the alternator power wire from the fuse block strait to the amp gauge, and then from the amp gauge to the alternator?
Or did you wire it a different way?

I will most likely be modifying my gauge to work with the volt meter since it (the EZ harness) is already wired for a volt meter and I already ran all of my wiring under my dash, but I want to know how you hooked yours up just in case...

The EZWire harness was designed to use a volt gauge. You just used the same wire that powered the rest of the gauges and connected it to the volt gauge.
There is a #12 wire that is labeled "alternator power" and a #10 wire labeled "solenoid power" that connect to the rear of the fuse panel. I mistakenly said the main wire was a #12 in my first post but it is a #10. This is the wire that you route through your amp guage. If you route the alternator wire through the amp gauge I think it will only read toward the charge side but would not go negative. Also if you connect the alternator directly to the battery like they show in the instructions your amp gauge is only going to read toward the discharge side.
Regardless of how you wire your truck, be sure to use the fuseable link that comes with the harness.

[Russell Ashley]

Originally Posted by SHORTDOG99

Same here! I already ran all my wires but want to keep the stock gauges...what do i do?

You cut the main wire that is labeld "solenoid power" in the EZWire harness at a point where the two cut ends will reach the amp gauge when the cluster is installed. Put a female tip in each end and plug it to the amp gauge. There's extra male tabs on the gauge for the wires and the bypass jumper.

[OrrieG]

So, just so I am clear on this, the "solenoid power" is cut, goes to one side of the amp guage, then from the other side of the amp gauge to the altenator? I have an EZ wire harness too.

[_Ogre]

orrie
look at mad electrical link and yes, if you use the alternator wire in the panel, the wire to the starter solenoid will be cut to wire thru the amp gauge.
on the diagram where the welded link is, would be your fuse block.

[Russell Ashley]

Originally Posted by OrrieG

So, just so I am clear on this, the "solenoid power" is cut, goes to one side of the amp guage, then from the other side of the amp gauge to the altenator? I have an EZ wire harness too.

No, not to the alternator. The "solenoid wire" in the EZWire harness is the main wire that powers the entire harness. It connects to the rear of the fuse panel and uses the connection at the starter solenoid just as a connecting point to tie it to the battery. It is a #10 wire. You cut this wire and put connectors on the cut ends and plug it to the amp gauge. The alternator wire is not affected by any of this and is connected normally.

Also: With the Vintage Air system the the ignition switch only provides power to the relays that control the blower and compressor clutch. The power to run the blower and clutch comes from a fused direct connection to the battery so doesn't come through the amp gauge.

[TX58]

How about a aftermarket (stock ) harness with HEI and alt wire? Can someone draw a diagram? I too need this mod.
Posted via Mobile Device

[OrrieG]

Thanks, I was working of memory, and now understand. Good point about the VA power too, I would have assumed it came from a circuit on the fuse box.

[Blue72slab]

I highly recommend folks who want to keep the old amp gauge read the post Orge linked above. On the stock setup if your 50-60 yr old gauge goes bad you are not going anywhere and I would only use it if the truck is bone stock. I believe there is a way to use the amp gauge without all the power from the truck going through it - maybe the jumper does that?

Originally Posted by TX58

How about a aftermarket (stock ) harness with HEI and alt wire? Can someone draw a diagram? I too need this mod.
Posted via Mobile Device

For my HEI I used the original coil wire to turn on a relay that is powered by any 14V source like the horn relay or main junction block. I got power from the junction block I added that the alternator wire is hooked to on the firewall.

[Russell Ashley]

[QUOTE=Blue72slab;5146604]I highly recommend folks who want to keep the old amp gauge read the post Orge linked above. On the stock setup if your 50-60 yr old gauge goes bad you are not going anywhere and I would only use it if the truck is bone stock. I believe there is a way to use the amp gauge without all the power from the truck going through it - maybe the jumper does that?


Blue, re-read my first post on this subject. The frame of the amp guage is capable of carrying a lot of current by itself. The jumper in parallel with the gauge frame divides the current that actually flows through the gauge. If you have it set up like I described and if all of your slip on connnectors are tight you are not likely to have a problem. Also as I mentioned, you should have a fuseable link in the main wire.

I'm using a new GM 10SI 90 amp alternator with the wiring and gauge configured as I have described with no ill effects.

As for that madelictrical website I suggest that you take his advice with caution. He's obviously a Chevy guy who gives his slanted opinion and likes to bad-mouth Mopars.