Amp meter bypass. To be clear

[will e]

I want to upgrade my alternator to a simple single wire and higher amps. I still have my amp meter connected. I also have a separate volt meter.

I have read a few posts about amp meter bypass. Some seem more complete than others.

But this should work right:

Disconnect Yellow 'return' wire coming from amp meter at solenoid. Secure the connector so it can't ground, perhaps eventually remove from the firewall junction block. This will disable the AMP meter from working.

Attach single wire from new alternator to positive on the battery or battery side of the solenoid. (A fuse or breaker is recommended)

With the original red wire to the alternator I can either 1. Attach it to the alternator post with the new wire. 2. Attach it to the battery side of the starter solenoid or 3. Attach it to the battery. This red wire feeds some of the lights and interior stuff.

Is my understanding accurate?

[PossumJr]

Below is what your current wiring situation should be, splice and wire names might not apply to your particular year but It should still be the same wiring, etc.

https://i.imgur.com/KvSyAco.png

I have only done the bypass in the sense that I moved the two ring connectors to the same post on the ammeter to just bypass the internals, so I can't speak from experience on a 1-wire swap but this is how I would do it:

https://i.imgur.com/C4QZUpu.png

In trying to reuse what I could, I would connect the alternator straight to the solenoid post with a new wire since you will already have a cable from the battery to that point. I don't think it really matters either way, but I would reuse the existing red wire that originally went to the alternator output, splice in a new fusible link and connect that to the solenoid and ditch the old yellow return wire from the ammeter as that will completely bypass it. I think this would be the quickest way as I don't see any reason you would have to mess the any of the wiring in the dash and could leave as-is without harm.

Alternatively you could reuse the yellow wire since it has the fusible link already, but then you would need to address the fact the ammeter will still be in the circuit to the "big splice". As the ammeter would no longer be responsible for also dealing with charging current and would only be measuring current drawn by accessories it probably won't be as unsafe as before, but at this point you could bypass it in the dash if desired.

[will e]

Ah, good point on the fact the original wire isn't fused. I think I read that several times but it never really sunk in. I am going to keep the red wire, I have an auxiliary fuse block on the fender with a couple of open spots:



And ditch the yellow wire. I will wrap it off at first and after I am confident my electrical system is still working, I will either disconnect it at the ammeter or the firewall.

Thanks!

[PossumJr]

I don't recommend just using a regular fuse, a fusible link was used for a reason as the current can be quite large (large enough a blade style fuse won't handle it) and with brief current peaks that a link can handle whereas you would need a properly selected slow blow style of fuse. Each individual circuit should still have a fuse (lights, heater, AC, etc), but on a main branch such as this stick with the link. Any chain auto parts store and plenty of online retailers to buy new ones.

Think of it as a form of shtf protection while the fuses are the first line of defense. Just like the breakers in your house and the individually fused appliances and electronics plugged in the wall.

I also forgot about using one in line from the alternator to the battery/solenoid. Do that as well.

[tgreese]

The fusible links are there to protect the wiring from the battery in case of catastrophe, like a wreck. They keep the battery from shorting to ground and creating a fire. Since they are bonded right into the wiring, they are reliable and act just like wire in normal operation. I'd definitely keep them and not replace with a fuse. How often do you need to replace the main fuse after a catastrophic wreck?

The ammeter circuit is a loop through the dash. Charge current from the alternator goes to the bulkhead connector, up to the dash. There is a splice there that feeds power to the dash, ignition and lights. The wire continues to the ammeter, where it goes through a shunt (thin piece of wire) inside the ammeter. The wire then continues back to the bulkhead connection, goes into the engine compartment and ends in a fusible link that connects to the starter solenoid, and then via the battery cable to the battery.

The objective is to get rid of the ammeter, and break the loop. Send charge current directly to the battery. Send power from the battery to the dash and stop. No loop. Here's what I did:



Here before is at top and after is below. The colors are right for my '82, but some Jeeps have red wire in place of the yellow. The wire labeled "14 ga" is a fusible link. "K" is a splice between the existing fusible link and the yellow wire. The original 10 ga alternator wire was rerouted to the solenoid through a fusible link so that the alternator charges the battery directly rather than looping through the dash. "B" is the splice under the dash that powers the lights, ignition, etc. The wire from "B" to the bulkhead afterward is not shown, but I just abandoned it in place. The red wire from the alternator was removed from the bulkhead connector and used as the new connection to the battery.

[will e]

So the fusible link is on the yellow 'solenoid' side huh? There isn't one on the red side?

I looked at the wiring diagram, it's a bit hard to follow since it is spread across several pages. I see the split in the red wire for the lights and such and it also appears it provides some power to the fuse box.

I don't think it provides 'all' of the power to the various accessories and such. In my case I have rewired much of it for various reasons. The stereo head unit has it's own power supply from my added fuse block. I also ran my own wire for the A/C since the terminal on the fuse box melted. No power windows or seats. That doesn't leave much to be powered. I am going to disconnect the red side first and turn everything on and use the ammeter to see how much power everything draws. That should help decide if I need a fuseable link or a simple fuse will do. The wire will no longer be carrying the full alternator charging load so it's amp usage may be pretty limited.

Thanks for the input guys. I have had this on my list of a while and will get going on it pretty soon.

[tgreese]

So the fusible link is on the yellow 'solenoid' side huh? There isn't one on the red side?

I read the diagram - it's the same as what I found when I looked at the harness. You have an '82, right? Everything should match from my sketch. The fusible link disconnects the battery from the Jeep in case of a short. Look at the circuit and imagine there is a short anywhere. With the loop configuration, you only need one fusible link to disconnect the battery regardless of where the short happens. When you connect the alternator directly to the battery, you need another fusible link to prevent a short in the alternator from grounding the battery.

I looked at the wiring diagram, it's a bit hard to follow since it is spread across several pages. I see the split in the red wire for the lights and such and it also appears it provides some power to the fuse box.

Dunno, I did not have any trouble following it. I have the '82 TSM in hard copy - maybe my copy quality is better than what you have. You can trust my interpretation or read the diagram yourself. Photocopy what you have, piece it together and trace out the circuit with colored pencils or whatever.

I don't think it provides 'all' of the power to the various accessories and such. In my case I have rewired much of it for various reasons. ...

You can add fuses to your own circuits if you like, but you need something to protect each of the new circuits. That won't defeat the purpose of the fusible link. If you bypass the factory circuit protection, you need to add your own.

[tgreese]

duplicate

[tgreese]

duplicate