AMMETER BYPASS ISSUES

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FSBOB
Posts: 23
Joined: Fri Jun 23, 2017 6:30 pm
Location: Minnesota

AMMETER BYPASS ISSUES

Post by FSBOB »

So I've been having intermittent charging issues with my truck. I've replaced all of the wiring from the headlights to the tail lights and replaced the alternator with a 90 Chevy style, all of which I got from Z&M Jeep. I have the Holley Sniper EFI with it's built in voltmeter which is how I know I'm having charging problems.

I tried the cheap mans way of doing the bypass by putting both of the ammeter wires on the same post which worked for a day until it burned out all the lights in my dash. Then I did the bypass by running a 10 gauge wire with a 14 gauge fusible link from the alternator to the positive side of the starter solenoid, then rerouted the original alternator wire to the positive side of the starter solenoid. It worked great for five minutes then I lost all charging to the battery. I'm fairly certain the fusible link went. Also, I had the alternator tested and it tests good.

I'm just looking to get my charging system square before I put the motor back in my truck on Saturday. I'm afraid this does have me scratching my head. Can I run a larger wire straight to the positive side of the battery without any fuses or fusible links? It is a self regulated alternator. Thank you for all of your help.
1976 Jeep J20 401, T15, Dana 20, Holley Sniper EFI, Hedman Headers, MSD Ready-to-Run Ignition, 33" Cooper MTP's :fsj:

twisted frame
Posts: 637
Joined: Wed Mar 27, 2013 9:41 am
Location: Massachusetts

Re: AMMETER BYPASS ISSUES

Post by twisted frame »

I'm sorry I don't know how to answer your question but I've been reading up on it because I've always been curious about the ammeter bypass. Have you read Mad Electrical's take on it? http://www.madelectrical.com/electrical ... uges.shtml
73 J4000. 360, MC 2100, T18A, D20, stock closed knuckle Dana 44 front, 60-2 rear. Warn Lock-O-Matics, Warn/Belleview electric winch, true duals with glasspacks, old-school front diff skid plate, used 265 Toyos on 16" AR wheels.
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az chip
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Location: Mesa, AZ

Re: AMMETER BYPASS ISSUES

Post by az chip »

If you re-wired the whole Jeep we would be hard pressed to troubleshoot that. Did you wire it standard per the year wiring diagram? or is it modified? Why did the wires fry? What is the output amp rating of your chevy alternator?
'81 Cherokee Chief 81 WT Chief/MSD 6/Holley Sniper/ Rusty 4" Spring lift/ Bulltear oil adapter/K&P Engineering Oil Filter/ NP 208/ Serehill Light Harness/KC LED Headlights/ Evil Twin Fab Roof Rack and sliders/ Ross mirror mounts.
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tgreese
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Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: AMMETER BYPASS ISSUES

Post by tgreese »

The alternator output voltage changes based on feedback about the battery voltage to the regulator. If you burnt out the bulbs, the only way I can think for that to happen is if you wired the alternator wrong. Some use the "one wire" Delco alternator, but the factory used a 3-wire connection. In addition to case ground, there is the large charge wire plus a plug on the alternator with 2 connections labeled 1 and 2. Terminal 1 is the "exciter" wire, often used for an alternator light, and terminal 2 the "sense" wire that tells the regulator whether to increase or decrease alternator output. If you connect these wrong, you could send the alternator into maximum output at an overly high voltage. Either that or your alternator is defective.

Az chip's point is a good one - if it's not the factory wiring scheme, we can't help you much. If you want an example to work from, the 1976 six cylinder Jeep CJ (not truck or wagon!) wiring diagram in the 1976 TSM here (http://oljeep.com/edge_76_tsm.html, section 22, page7) has a diagram you could copy. This Jeep uses a Delco alternator and a voltmeter in place of the J20's ammeter, with a similar layout and features to your '76 J20.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
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