Voltage drop issue- where to go from here

[Viper21700]

Ok guys, at the request from another member, Im starting yet another electrical thread dealing with voltage drop. I hope to document the steps with the assistance of other members so people can get a better understanding, as well as solve the issue Im having.

Background- 1966 Plymouth Barracuda, LA360 V8, Isolated field alternator installed already using single field voltage regulator (second field jumpered to ground). This system works ok- but provides very little charge at low RPM. Will be upgrading ignition system to electronic ignition in near future, so the time has come to upgrade the VR as well.

Problem- Installed mid 70's two wire voltage regulator and wiring harness, voltage spikes to 18v when engine RPM's increased.

Troubleshooting steps completed-
Utilized dremel tool to clean grounding points to bright shiny bare steel, cleaned all bolts and grounding strap ends as well.
Installed second ground next to battery directly off of Negative terminal post.

Check for voltage drop from + terminal on battery to starter relay stud- .028V (well within suggested specifications according to Dart273)
Checked for voltage drop from + terminal to positive ignition point on ballast resistor- 1.0-1.1V drop. Attempted this with all accessories turned off, but ignition on (engine off of course)

So where should I go from here? Ive narrowed down one of my issues to the ignition circuit, but where do I start looking on this circuit? Ive heard people say just run the alternation VR off of a relay, but I consider this a Band-Aid solution at best. It might cure one issue, but Id rather complete the job correctly, and learn the evil intricate nature of the magic smoke devil known as 40+ years of wiring disaster.
Thanks guys- lets get this party started.

 

[Viper21700]

Also another indication of an issue I noticed the other night was the temp gauge on the dash (I have an aftermarket installed under the dash as well) The dash gauge works when it wants too. on occasion, it will rise to the normal heat range the engine is running at, then drop off back to nothing... On my long road trip (475 miles from Va Beach to Aiken SC on Monday) I noticed this happening.

 

[RedFish]

To do this upgrade you had to add a blue switched 12 volt wire to the alternator. Where did you attach the blue wire?
Just so you know... In a pre 70 model... The blue switched 12 volt wire from your ignition switch is actually 2 small wires in the same terminal. One goes to the instrument panel. The other goes through the bulkhead connector and on out to power the points ignition and charging system. When the electronic ignition, isolated field charging and other items were added to this blue wire circuit, not only did the ignition switch contacts get heavier but the wire gauge also got heavier.
Regardless how you answered my question above.. You would be wise to add a relay just beyond the bulkhead connector and properly supply those upgrades. This might even extend the life of your ignition switch contacts.

 

[Viper21700]

I removed a voltage regulator wiring harness from a mid 70's Dodge P/U, had three wires on it, one to switched ignition, then the other two to the alternator (black one to lower post (the one that's currently jumpered to ground with my current VR) and a red one to the upper post (which is currently connected to the green wire on the single pin VR I am using currently)
My switched ignition line I ran to the switched source that the old Voltage regulator was ran to, IE the lower pin on the ballast resistor.

Oh and FYI- I don't have a bulkhead connector on my vehicle. It was removed and bypassed prior to my purchase of the vehicle, and was covered with a large rubber sheet with holes drilled in it to let the wiring pass through (actually a pretty ingenious way of sealing that hole... pretty water resistant lol)

Now- Redfish, your comment about the relays... Where would I install said relays, where would I run them too, and how would I wire them? Any suggestions? PM me with some details.. Im not against using relays, not in the least (I love relays actually... they help keep the magic smoke inside the wiring instead of escaping to the outside lol) but I still want to get to the source of my issue.

 

[RedFish]

Just one relay. The blue wire coming from ignition switch would only signal/energize the relay. The 12 volts going to systems would come from battery terminal stud on the starter relay, with inline fuse of course.
Field wires are commonly blue and green. Your blue is black instead ? Could be. I really don't know where they changed the colors.
I'm not understanding if you have attached a black harness wire to ground or only attached a jumper from a alternator terminal to ground.

 

[Viper21700]

On the original VR/Alternator (Square back isolated field Denso alternator, and FYI- already checked the alternator out, case has a good ground, both points are insulated and no continuity to ground) How it was ran was
Red ignition wire---- VR---Green field Wire----- Alternator upper field post.
Lower alternator field power/Black wire----attached to ground at case

I removed the old wiring and ran the new stuff, when it spiked I swapped back to the old components and it worked as before, but would much rather get rid of the old regulator and go with a slightly not as old regulator (actually brand new regulator from my local automotive electrical shop)

 

[Viper21700]

Also I ohmed out the new wiring harness, all wiring was good.. Cleaned all the wiring harness connections as well.

 

[RedFish]

I just don't know. With a later solid state regulator that blue and green would go to the alternator and there wouldn't be a jumper to ground on either of those. Only chassis grounds would be the alternator to it mounting and regulator to its mounting.

 

[Viper21700]

After the weather clears up Ill take a picture of how the system is set up now with the old setup.. then take a picture of the new wiring (sitting in my shed since I pulled it back off)

 

[67Dart273]

You really just have to get it together and test.

GROUND. I don't know about a slant, but on V8s, look at the front of the pass side head. Those same holes are on the REAR of the driver side head. Go buy a short no4 "starter" (ring to ring) cable and bolt to one of those holes, "U" down, and bring the end back up and bolt to one of the master cylinder bolts, or drill / find a hole in the firewall, scrape clean, and bolt down using star lock washers

Clean up the regulator mount remount with star locks. Do what you have to to get solid bolt mountings Use star locks, or even a separate ground jumper, at least no10

To CHECK ground. Run the engine at "fast idle," get the battery as normal as possible, and make this test first with all accessories off, and again with lights, heater, on

Probe the battery NEG post, and the other probe stabbed directly onto the regulator mounting flange. Make sure to stab through chrome, rust. You are hoping for a very low reading, more than .2--.3V is too much, and zero is perfect

============================================

Harness drop. Pay attention. Find "switched ignition" under the hood. This is at the ballast, and on a 70 / later system, the switched wire at alternator field. Hook one probe of your meter there, and the other at battery POS itive post. Turn the key to 'run' with engine off, and set the meter to low DC volts. Again, you hope for lower not over .3V at the most. IF this is high, one way "around" it is to break the switched ignition line coming out of the bulkhead, and install a relay, fused off the starter relay, to operate ignition, regulator, alternator field

==============================

If the two tests above do not show up anything, look carefully at the VR connector, make sure it's clean and tight. Check all battery connections and grounds. IMPERITIVE that the regulator is grounded to the battery NEG post "same voltage"

If this does not cure the trouble, change the regulator, maybe try a different parts store

If THAT does nothing for the problem, try a different battery

And do NOT forget that multimeters are not infallible. I just recently found a very "off" meter at a friends down the alley. I was one of those cheap "red" things of Horrid Freight caliber.

=====================================

Also, in rare cases, the green ground wire returning from the alternator brush to the regulator could be shorting. This could happen at the wire, I E bare wire, or broken damage brush holder in the alternator.

 

[Viper21700]

As promised, here are the pics of what Im working with. The first pics are of the way it is currently wired. Coming off of the old VR, is the green wire, feeds directly to the top field stud on the alt.
The red wire feeds from the ballast resistor.
On the back of the alternator, the second field wire is jumpered to ground on the case (which works as I said, but not at idle)

The last two pics are of the replacement wiring harness from the mid 70's dodge pickup I found at the junkyard.

 

[RedFish]

Red wire on large alternator stud is attached to ballast resistor ?

 

[Viper21700]

no- primary power output is going to starter relay stud. Switched ignition is coming off of the ballast resistor heading to the VR.
When I tied the new regulator in, I tied it in with switched power installed the same way. Im going to wind up running a power output wire from the alternator anyways, but am going to run it directly into a prime power distribution box (probably off of a mid 90's dodge dakota)

 

[RedFish]

ok either way the ballast resistor is not a good place to get 12 volts.

 

[Viper21700]

I was wrong.. I went out and double checked, power output is ran into the ameter on the dash, minus the bulkhead connector..
Ok Redfish- teach me your magic... I dont like having heavy loads ran into my interior... Had one too many incidents of Class Bravo fires in my lifetime (US Navy.... had more than one power panel Arc-flash around me) So Im going to move it tomorrow.. Where should I re-route it too, and how will I still get power to my interior?

 

[Viper21700]

Also- it looks like the lower stud on the ballast resistor is power, before it hits the resistor. Top plug of resistor Im guessing runs to the coil/points???

 

[Viper21700]

Dart-
I ran the tests you gave me. Im going to run a ground cable from my new VR to the neg post of the battery tomorrow as well, or can I tie it into the ground cable on the block?

 

[RedFish]

I'm not the best helper for your situation. Del 67Dart273 and a couple others are more familiar with the early A and the 4 post ballast resistor systems.
Wire color may not make a difference to some. I cant keep my mind straight when the colors are different.

 

[Viper21700]

Well I pulled the dashboard out tonight (working on the gauge cluster anyways, and checking out the wiring behind the dash) surprisingly it only took me about ten minutes of work to snatch it out. So whats next? I think Im going to install my oil pressure, temperature, and voltage gauge in the non-functioning gauge holes. going to bypass the ammeter most likely anyways... I thought there was supposed to be a voltage regulator on the back side of the dashboard specifically for the dash???

 

[Viper21700]

Found some interesting repair work on the back side of the dash.. Take a look at the pins....
Looks like someone wrapped a small piece of copper wire around each of the pins, then soldered them onto the board... but didnt solder the wire to the pins, just a quick wrap around... Maybe some of my problem is there?

 

[Purple Haze]

Have a look here lots of good info http://www.madelectrical.com/

 

[RedFish]

Well I pulled the dashboard out tonight (working on the gauge cluster anyways, and checking out the wiring behind the dash) surprisingly it only took me about ten minutes of work to snatch it out. So whats next? I think Im going to install my oil pressure, temperature, and voltage gauge in the non-functioning gauge holes. going to bypass the ammeter most likely anyways... I thought there was supposed to be a voltage regulator on the back side of the dashboard specifically for the dash???

Instrument voltage regulator is inside your 3 post fuel gauge

 

[Viper21700]

discovered an issue, that I was able to fix in a half a second... was wondering why my gauge only goes down to 1/4 tank when empty or turned off. turns out the gauge works fine, the needle was bent a little bit.. adjusted it to read empty now. should fix that issue lol. I checked out mad electrical's website earlier. doing the ammeter bypass tomorrow, borrowed my buddies Weller Soldering station with all of his soldering stuff. Also grabbed a roll of number 10 and number 12 wire from him (hes an electrician by trade, and does auto electrical on the side... His shed is like my private loaner tool store, I borrow something from him, six months later he borrows his tool back.. got to love having a neighbor whose wife is my sons godfather ) So-
heres my plan for tomorrow-
Step one- Bypass Ammeter IAW Madelectrical's instructions
Step Two- Remove the non-working Gauges (oil pressure, engine temp, and Ammeter)
Step Three- install the Sunpro Oil pressure, Temp, and Voltage gauge into the cluster
Step Four- trace down a burnt wire I found tonight and replace with number 10 wire

And while Im at it, he handed me a plastic baggie full of graphite (he also makes his own shotshell shot, and rolls his shot in graphite) going to clean and graphite lubricate the speedometer cable. Sounds like a fun filled day of tearing stuff up!!!!

Oh- and here is a good set of instructions on removing the gauge cluster-
http://www.jamesmskipper.us/Barracuda/InstrumentPanel.html
Mind you this isnt my site, just found it and it worked great.. I didnt have to remove my ignition switch, and I found it easier to partially pull the panel then unscrew the speedometer cable..
Hopefully this guy is a member of FABO.

 

[Viper21700]

Oh and if anyone needs my guages after I remove them, shoot me a message, my ammeter works fine, and most likely the other two do as well, just either bad wiring in the harness or a disconnect somewhere down the line.

 

[67Dart273]

Dart-
I ran the tests you gave me. Im going to run a ground cable from my new VR to the neg post of the battery tomorrow as well, or can I tie it into the ground cable on the block?

Ground to the block will be fine

What was the results of the voltage drop tests?


The stuff on the cluster was an attempt to repair loose connector pins. They are originally simple crimped into the board. Clean them up and solder them. The jumpers are OK if done well and actually make good contact. It appears that the board may have been damaged by something shorting at some time. These old girls are poorly protected, fuse wise. The "ignition run" circuit, which also feeds power to the cluster is not fused at all, other than the fuse link.