Okay Ive posted a few times here before but I have finally fixed a problem I was having.

A while back my battery was installed backwards = Fried alternator, Regulator, and the battery wires. So I replaced all of those things.
After that, my voltage was running between 14.5-15.5 volts, and the Ammeter was going back and forth .. lights flickering, etc etc..
Finally,
I traced it down to the yellow wire to the voltage regulator, which was connected to a Red wire that I believe goes to the Ammeter. Well, I put the yellow wire directly to the battery, because the Red wire it was attached to always has power, and my alternator and regulator started charging at a steady 14.5 volts, no more power fluctuation and flickering lights !! Problem solved .. but I have a new problem.

So I was wondering about this red wire, hooked it up to power to see if the ammeter was reading, then I grounded it out and my dash started smoking.

Pulled the dash and the gauge cluster, and the circuit board fried where it goes to the Ammeter .. the wires leading to it are also semi-shorted ... so I believe that originally caused my voltage problem, but now I dont have a gauge.

I was wondering, can I get a new circuit board from a junkyard, and replace the wires going to it ?? Or is there a way to test the Ammeter ?? or just bypass the circuit board and run wires to the two posts on the back of the gauge cluster to the Ammeter ??

I'll try to do something with it tomorrow, but for now, one problem solved, another one pops up.

When the voltage was acting funny, I would turn the Igniton switch to the Run position, and the Ammeter needle went all the way to the right. Started it up, and it would go between the middle and far right position. Once I disconnected the red wire / yellow, it just stayed in the middle. Is this wire supposed to supply power to the A terminal on the voltage regulator ?? Or was it supposed to go all the way to the right when the ignition is turned to Run ? Anybody elses truck do this ?

Any help or information is appreciated.

- Dan

 

I assume this is for the 73 in your profile as you didn't mention it here on this post ?

Good luck finding a pre 74 cluster or the parts for it unless you have a great wrecking yard nearby.

You have to go with the original ford way to make sure its right.

Gauges can be had but never fool around with VR wires without a schematic.

These may help.

http://www.clubfte.com/users/mil1ion...lusterBack.JPG


http://www.clubfte.com/users/mil1ion...ingcircuit.JPG

 

Oh yeah, its for a 1973 F250. That totally slipped my mind when I posted it.

There are a few junkyards which have older Ford trucks / Vans, so I may be able to find one close to my year.

I havent really done anything with the voltage regulator wiring after troubleshooting everything. Its basically stock, except for the A wire which I have seen quite a few wiring diagrams.
I am getting a constant 12+ Volts from the original A wire even with the ignition off, which is why I overlooked it for a while - Tested all of the alternator wiring for resistance and it was good. Finally took that wire off and put it directly to the battery and thats when my voltage finally went steady 14.5 volts, I just made the mistake of grounding the other end of the wire to test the Ammeter .. dumb idea. Fried the gauge cluster circuits, but from what I can gather, the wiring was already somewhat bad - probably from installing the battery backwards to begin with, that it was causing my voltage problems. So either way, it needs to have the wiring replaced. Im just seeing what I can do to get it working.

My truck is all original, been in the family since my grandparents bought it brand new, driven all over the United states, and Canada .. still only has 85,000 original miles, so Im trying to keep everything factory or original in working condition.

- Dan

 

Just another question .. Ive been doing some research.
Where is the Shunt resistor located on the 1973 Trucks ?? Is it built into the Ammeter ?? I havent seen anything inside of the engine bay yet and I have alot of the tape stripped off the harnesses already. This resistor is necessary for the Ammeter to measure voltage properly, correct ??

- Dan

 

The shunt resistor is actually the wire itself. The two small wires from the ammeter are welded to the large wire in two locations. The wire between them is the shunt.

 

nevermind, read more of this thread

 

Okay, so is the Shunt the wire coming off the Starter Solenoid, going to the splice to the Alternator ??
If this wire was the Shunt, it had a Small black plastic type fusible link or something on it ?? Because when my battery shorted everything out originally, this wire fried up to the Fusible link on this wire and I cut out the fuse and wired it directly to the Starter solenoid.
I see where the Yellow wire for the Ammeter connects into this splice.
The Red wire never was connected to the battery or anything with 12V+, it was wired to the A terminal on the Voltage Regulator.
So It looks like my wiring hasnt been correct for a long time, Ive never really paid attention to the Ammeter until I started fixing the voltage problem I was having.
If the wire with the Fusible link is the shunt, which I am guessing it is, do I need the section that I cut out to make it work correctly ?? I will have to try and find that at a junkyard or something.
I can take a picure of my wiring if it helps, its kind of messy right now though.

- Dan

 

The fusible link is just that a "Fuse" ible* link instead of a Buss fuse.

The shunt is actually on the ammeter gauge.

http://home.cogeco.ca/~rpaisley4/Ammeter.html

 

Okay so if thats the case, I should be able to just get a new printed circuit for the back of the gauge cluster and tap the red wire onto a Battery lead ??

I tested the restance between the two posts on the back of the Ammeter gauge, and it shows 0.3 ohms, the wire loop to and from the gauge show about 0.1 to 0.2 ohms resistance, so the only part that really fried is the circuit.

Another thing I was thinking if I cant find the printed circuit would be to tap into the red and yellow leads before they plug into the back of the gauge cluster and wire them to the two posts on the back of the gauge, is it possible that might work ??

- Dan

 

What would you do with the proper part of the harness that covers that circuit where it plugs into the Printed Circuit Board ?

Why not put it back the way it was ,the way Ford built it ?

 

Not in our trucks it's not. Unless it's another change made after the '76 year. If the shunt is on the meter, then the full output of the alternator would be routed through it. I have pegged the meter with a 1.5 V D cell battery.

DDub, If the yellow wire is spliced into the alternator output wire close to the alternator, then yes the red wire shoud be ok on either the battery lead or on the starter solenoid, battery side (less acid there)

 

The shunt is only found "on the ammeter gauge" in an aftermarket unit (which are an extreme fire hazard and junk!). The OEM shunt is the wiring in the harness just trace down the two wire leads from the gage.

While you are working on the flex circuit clean ALL the contact points and grease them with some silicone dielectric grease for protection.

 

My Mistake.
Sorry,slap me silly

I was a sure the Ford ammeter had the shunt in it in the 73..

 

I would prefer to replace the circuit on the gauge cluster if I can find one at the junkyard .. like I said, Im trying to keep everything original.

I also have the 1973 Ford shop manual which was a little confusing in diagnosing my voltage regulator problem. Mostly due to the fact that the Red wire that comes from the Ammeter went to the A side of the Voltage regulator to supply power, which was resulting in a very erratic voltage output and was not wired the same way as the factory manual diagram.

So Now that I have that figured out, and Im pretty sure this wire between the starter solenoid and the splice half way between the Alternator wire where the Yellow wire is tapped in, is the Shunt wire - with the exception of a few inches missing after the Fusible link which was fried. So it should work to a certain excent, just not as accurate as the original Ford wiring - which I will also try to locate at the junkyard, Id rather have a complete wiring harness than one that has all sorts of splices of new and old pieces used together.

Thanks for the input guys .. I'm still doing upkeep on this truck to keep it in good condition even though it isnt driven very often.

- Dan

 

Also your charging voltage on the battery should be between 13.8 and 14.2 volts. Back in the old days when we adjusted the regulator voltage we would use closer to 13.8 for a road car and 14.2 for the little old lady that drove to church once per week. In fact for one little old lady we set it to 14.5 to keep her battery charged. Church was only a couple blocks away...