shunt rewire after gm 1wire altenator install

[madwomanwithastihl141]

I have a 1968 f250 4x4 camper special 3/4t manual trans. Was external voltage regulator. I installed a GM 1 wire alt. and can not figure out which yellow wire in the shunt to hook where to get my stock instrument panel volt meter to work. I hooked my 1 wire to the battery, then took the shunt part of the harness and hooked one end to the starter relay, and the other to the battery. My harness looks just like your picture in FAQS for the shunt but I put the yellow into the yellow they show for the ( horn?} and nothing happens. When I put the yellow back into the yellow, which I believe would have been 152 to the external regulator, I thought I had it. When I turn my headlights on, it discharges as was discribed, only it does not come back to the middle until I turn the lights off. maybe this is fine. I do not know. most rigs recover the volts after a minute or two.Will you please let me know? I have been up to page 27 in your electrical forum , and have learned a lot , but am going blind looking for this answer. thanking you in advance, m

[mrollings53]

The stock gauge isn't a voltmeter but a ammeter. It will only move when there is a change in the flow of electricity. It sounds like it's working properly from your explanation. Can you post a link to the wiring diagram you used to get the guage to work?

[madwomanwithastihl141]

I am sorry. Maybe my request got lost in my post.Let me try to reword it. I am looking for a link that shows what to do with the section of harness that includes the shunt, the 4 prong connector, the 4 wire plug that goes to the regulator,etc.. when switching to a 1 wire GM alt. I used the info from "Shunt pictures" in the FAQS below , and "charging,starting and gauges in section H. I could show you how i wired it to get everything,(if my ammeter is working right) to work.

[madwomanwithastihl141]

Re: shunt rewire after gm 1wire install

Sent at: Thu Aug 16, 2012 9:48 pm
From: Thunderfoot
To: madwomanwithastihl141
You want to hook one wire at the starter solenoid battery wire and the other at the BAT terminal on the alternator. As this is a "Shunt" measurement it will not move the needle much on the gauge, as it is only taking a sample of what is going on. It only reads if the alternator is putting out a voltage to maintain a draw (headlight, heater fan, wipers, etc) if nothing is drawing a large current the needle wont move hardly any at all or if the alternator is not working show a discharge when there is a large draw.

Depending on which way you have the wires hooked to the alternator and battery, it will affect which way the needle moves under a load. You want it to read to the (+) side when you have the headlights on and the engine running and to the (-) side with the lights on and the engine off. Also, you need to have the main power wire to the cab (wire 37) hooked up to the BAT terminal on the alternator to get this all to work with a heavy wire to the battery from the alternator .
The way the amp gauge works is it measures the voltage difference of the wire from the alternator to the battery (38A). If the alternator is putting out current/volts it will be higher there then at the battery, if the alternator is not working and the wire 37 is drawing current the battery will have higher voltage then the alternator side on the wire 38A and show a discharge on the gauge.

This may help...

Image

Hope that helps.
Shayne
I'm not "Brand Loyal" Ford-Chevy-Dodge-Toyota I have them all, one even cross mixed...
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[madwomanwithastihl141]

Re: shunt rewire after gm 1wire install

Sent at: Wed Aug 22, 2012 6:48 pm
From: Thunderfoot
To: madwomanwithastihl141
Sorry I work 12hr shifts Sat-Tue and don't have much time for anything but work-sleep-eat-drive to work again.... so not on the internet until my days off...

For a one wire alternator you are getting rid of the voltage regulator and would wire it just like the diagram I attached before. All the diagrams are listed here http://www.fordification.com/tech/schematics_h.htm that I use for reference and what I use to modify them for applications and mods. Send me a link to the one you are looking at, and what year truck you have.

Wire 152 is used for the Voltage regulator only, has nothing to do with the Amp gauge,,, the Amp Gauge wires are RED and YELLOW wires 655 and 654. Wire 654 (Yellow) will connect to the Bat (only wire on the alternator) at the alternator along with the main power wire 37 (Black-yellow striped) to the cab. The Red wire 655 will connect on the starter solenoid on the Battery connection on the other end of the Charge wire between the alternator and the battery.

So you need;
One "main wire" (38 in that attached diagram) from the Alternator to the Battery connection on the Starter Solenoid (should be fused)
Wire 654 (yellow) with 4amp fuse in line and wire 37 (Black-yellow striped) will connect on the alternator side of the "Main wire", wire 37 should also be fused or fuse-link in wire (should be one from factory there)
Wire 655 (Red) with 4amp fuse in line will connect to the Battery terminal on the starter solenoid (other end of the "Main wire" (38 in that attached diagram) from the alternator.

Note: depending on your year of truck and options you may have had the Horn wire in the harness to the Voltage regulator/alternator.
Shayne