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Discussion Starter · #1 ·
trying to figet out how to wire my alternter to a voltage reg.

did a moter swap in my RC and elimnated my computer
friend told me that i now need to put in an extenal voltage reg,
i have all the parts just no idea how to do it. and it is the last thing
stoping me from getting my RC back on the road,

88 RC ( first year with tbi) the alt has looks like 5 wires, 2
i blive are just grounds, that leaves 3 one big one and 2 small, and that is were i get lost

john
 

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the big wire is the output charge wire, the 2 small ones go from alt to volage reg. cant remember which one goes where, but if there backwards on the alt, the gauge shows discharge. done that before.lol if you have a haynes or chiltons dodge truck book, there is wiring diagrams that should help.
 

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The big one is obviously the charging wire, and the 2 small ones are the VR leads. Both VR leads (one red, one green)go directly to the alt to those 2 terminals. I'm not real sure if it matters which goes where (if it does, someone chime in) Then you splice an Ignition controlled +12v into the red lead. This +12v source should be as close as possible to the ignition switch on either the IGN1 or IGN 2 circuit. This will give the VR a good picture of voltage demand..

Matt {peace}
 

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Discussion Starter · #5 ·
ok got the alternater working,charging great, but my battery was dead when i got out of work.
should the volt reg be wired to a key cercit or a constely on one.
i spliced in to my msd ingtion, thinking i used the wrong wire.
that is the only hard part i am haveing is what wire to splice into
 

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The green wire runs only between one of the alt fields and and the voltage regulator. The second wire (either red or blue) is ignition-switched power, and runs from the second alt field, to the VR, to the ignition switch (and probably a few other stops along the way)

Doesn't matter which field wire is hooked up to which field on the alt.

-SM
 

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Hello John,

Sounds like you and have a lot in common right now. I also have an 88 TBI that no longer has the computer and I am rebuilding the harness. Sounds like the only difference however is that the last owner of the truck installed a GM alternator that I am installing in a one wire self energizing configuration.

I hope you don’t mind if I pop in a couple of semi related questions to the group.

I have documented physically in the wires and seen in the wiring diagrams D3 and D4 that both wires from the Ammeter In Cluster (Red A11 -50 Way Bulkhead Disconnect # 43- and Black R16 -50 Way Bulkhead Disconnect # 44) both go to positive. Looks like the A11 to the battery and R16 to the original alternator harness. My question is should I just run both to the battery positive terminal since my new alternator feed line goes from the alternator, through a fuse and then to the positive terminal? Seems funny to me, I guess I don’t understand how the ammeter is working and why it needs two positives. As I understand it the alt I have has three wires on the case one for Bat, one for Field and one for Sensing. Does anyone think that anything from the original harness should be attached to any of these?

I am planning on using a marine bus bar for positive power behind the battery where the factory computer was, then extending all of the harness leads that connected to the old alternator black distribution block (that is now gone) and also all the leads that connected directly to the battery, to the new bus bar. I will be adding fusible link just before the bus bar to all the leads that originally had fusible links. All the positive power leads did not have fusible link however. Should I fusible link all the leads just to be safe? Does this plan of attack using the bus bar seem sound?

Also, would now be a good time to add the relays for the headlights as per the how to? Would it be worth doing, and could the mod make the lights burn out faster then normal?

Just to give you all some background, I don’t mind blipping the throttle to get the alternator charging, and I don’t know yet if the truck has an idiot light for charging since the electrical has been a basket case since purchasing the truck recently.

As always, I appreciate everyone’s help, and I apologize up front for somewhat jacking this thread.
 

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Hmm... Unless it's a 1 wire alt, you should set it up as a 3 wire. Do exactly what John's doing and put in an external voltage regulator.. 1 wire setups are notorious for providing low volts to the electrical system, thus straining your battery and any electrical equipment you may have or plan on later. An externally regulated alt has its sensing lead connected right in the middle of the electrical system, so it can get a better picture of battery charging demand, and equipment demand. It also factors in resistance loss in the wiring, which a 1 wire can't do.

Dodge trucks do not have a charging system idiot light, although if the alternator supports it, you can hook up the output to either the Maint Req'd or Check Engine lights since you don't have the computer. For the ammeter, the way the later ones work is it measures current flow across a shunt, rather than being a "Full Flow" type, where the ammeter carries the full load of the electrical system. Many an old Dodge truck burned to the ground due to this type of ammeter overheating and causing a fire in the dash. If you want rhe stock ammeter to work in your new harness, you have to strip apart the stock harness to find the shunt wire, then cut it out and splice it into your main battery lead. Your charging wire from the alt should go to your disribution block, and the lead from the distribution block to the battery will have the shunt. Then you attach the ammeter leads one to each side of the shunt. That way it will tell you whether current is flowing into or out of the battery. If you are going to do this, you will definitely also want to install a voltmeter. A voltmeter will give you a slightly better picture of what's going on with your electrical. The stock ammeter's not bad, especially if you're keeping the stock cluster, because no aftermarket gauges will fit in there.

All your main feeds, including the charging lead, should be fuse linked. In the event something goes radically wrong, the links will burn long before there's danger to the wiring. The marine bus bar sounds like a good idea, I don't see any problem with it.

Headlight relays are going to make your lights brighter, because the battery to bulb path is so short, and the wiring is so heavy, the bulbs get all the juice they can possibly use. Plus, none of that current is going through your llight switch or high/low switch, so your wiring is a lot safer. The bulbs may burn out faster than you're used to, only because they are getting more juice than they used to, but basically this is what the bulb is rated to operate at, so it'll still be within the manufacturer's life expectancy (a year or so). When you do this, get the H4 conversion lenses, and Silverstar H4 capsule bulbs.. Boy what a difference!! I get flashed by other people because they think I have my highbeams on. Then I let them have it! The high beams are blinding! I even use the Silverstars in my motorcycle.. They are expensive, but worth every penny. Be warned though, don't buy any of those "hyper white" or Euroclear, or any of that other crap. It's all garbage. Overpriced garbage at that.

Matt {peace}
 

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Hi Matt,

This information is very helpful. I just wanted to clarify on a couple of points.

Just so you know I ran a new 2 Aug (I plan on going with an alt that can put out more than 60 amps soon, and yes it is overkill!) main alt feed from the alt to a wafer fuse mounted in the small space just in the cleavage of the radiator support, and from the other side of the wafer fuse the alt feed goes directly to the positive on the battery. I no longer have the alt harness and all the fusible links. It sounds like I may not be able to tell with my setup whether juice is going in or coming out of the battery, doesn’t it? I’m not sure… What do you think will happen if I connect both ammeter wires to the battery post where the alt feed is? Because I can’t see how I will be able to break up -if you will- the alt feed and battery feed voltages with the one wire alt directly to the battery.

As I under stand it, the alt I have has an internal regulator. (My factory voltage regulator was gone when I got the truck.) The juice to the truck seems to act regulated at a touch over 14 volts.

I know that you may not have the 88 factory manual, but would you reckon that the shunt wires you describe are the two wires that I described coming from the ammeter (red and black) both of which go through the distribution block?

Thanks,

Jason
 

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Hmm, unfortunately without the original harness, (unless you visit a U-Pull) you won't be able to use the stock ammeter. Basically there's a short piece of slightly smaller wire (probably not even a full wire gauge difference) inline with the charging circuit, with the ammeter leads connected to either side of it. This is the shunt. What happens is the majority of the current flowing passes through the shunt, while a "metered" amount is diverted through the ammeter, due to the very slightly higher resistance of the shunt wire. The amount of current flowing through the ammeter is directly proportional to what's going through the shunt. Ammeters must have current flowing through them in order to operate. If you connect both leads to the same power source, it is just like a short-circuit. Current takes the path of least resistance, so nothing will flow through the meter. The reason a shunted-type meter is used is because it keeps the high-current wiring under the hood, and out of the bulkhead connectors. Just ask any person here with a pre-1980 truck what their full-flow ammeter and bulkhead connectors look like. 99% will say toast, because the full current of the truck's electrical system runs through 2 little tiny connectors in the firewall, and through an ammeter that melts. ;)

Look at this diagram and it should be a little clearer for you. I enhanced the thicknesses of the wires so you can see the difference, and the different size arrows show how the current is divided up. Red indicates power flow out of the battery (needle deflecting toward "D"), and Blue indicates power flow into the battery (needle deflecting toward "C").


Like I said, without a factory shunt wire, whose resistance the stock ammeter is calibrated for, there is no way to make it work. Unless someone knows the correct resistance or wire gauge to use. I think it would be easier to just go to a junkyard and strip one out of another truck.

Matt {peace}
 
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