Question on wire from bulkhead connector to alternator

[Dino]

Now that I have bypassed the ammeter and have a 6 AWG wire going from alternator to starter relay, do I keep the 12 AWG black wire that connects the alternator with the 'P' slot on the bulkhead connector?  This is the same wire that splices under the dash where one went to the ammeter and which is now connected to the red wire that was connected to the ammeter.  I know this black wire needs to be connected to complete the circuit but where?  Instead of keeping it at the alternator, should I not cut it shorter and hook it directly to the 6 AWG wire on the starter relay?  In this scenario I have a 6 AWG wire going from alt to starter relay.  From that same starter relay stud another 6 AWG wire runs to an 80 amp ANL fuse which in turn goes to the positive batt stud.  Again from that same starter relay stud, a 16 AWG fusible link goes to the 'J' slot on the same bulkhead connector.  Under the dash, this becomes the red wire running to the ammeter.  If you're confused, that's how I feel!   

This crude diagram shows the current charging setup.  The black wire in question can, I believe, can either go to the alternator or to the starter relay stud.  The latter being the better idea or at least the cleaner looking.  I just can't figure out what that does to the fusible link though.  With all these modification, what exactly is it protecting?  Somewhere, this big under dash splice runs to the fuse block as well if I recall.

 

[cdr]

if you do connect to the starter relay it needs a fuse,because you will now have 2 voltage supplies to the inside,i made mine a separate circuit & hooked up a relay off the accessory side of the fuse box to take the load off the ign swtch & the original fuse link circuit.

[cdr]

so the way mine is,,# 6 from alt to starter relay ,the original fuse link still in place,the alt wire going to bulkhead is not used,but i ran a # 6 off the starter relay with a 40 amp fuse to a relay that is activated by the acc,circuit,, of the ign switch, so it spreads the amp load out from just the original fuse link. with it hooked up this way my ac blower blows much better.

[Pete in NH]

Hi Dino,

That black #12 wire from the alternator to pin P on the bulkhead connector originally went to one side of the ammeter we can call the load side. It also as it came off that side of the ammeter, went to a big spliced junction that feed the original fuse block and all the electrical requirements of the car. You still need that connection to power the car. Since you've done a substantial rewiring , I would do the following- 1) ignore the #12 black wire from the alternator to pin P on the bulkhead connector. 2) Tape it back to the existing harness or remove it entirely. 3) I would also pop the pin out of the bulkhead connector at P. 4) Run a new #10 gauge wire from the starter relay stud from the battery, though a new 50 amp maxi-fuse directly through the firewall to that spliced joint that used to have that black ammeter wire going to it. That will power up the car as before, but get the bulkhead connector out of the picture as well as provide a new master fuse. Its important that this line has a fuse in it to take the place of the original fusible link. That 80 amp ANL fuse takes care of the alternator path to the battery and the new 50 amp fuse takes care of the rest of the car. You can then just remove the original fusible link connection on pin J.

[Dino]

Thank you gentlemen   

Just so I have it right:
-Remove the black 12 gauge wire coming from P on the BH connector in the engine bay
-Run a 10 gauge wire from the starter relay battery stud through the firewall, to an inline 50 amp fuse, and connect it to the black wire on the other side of the BH connector.

I bought a brand new BH connector and new Packard 56 terminals.  Do I really need to bypass these now that the 6 gauge wire is taking the brunt of the load?  I will if I have to but just curious.

Can I go from the maxi fuse to the length of black wire under the dash that runs to the splice or do I need to find the splice and get as close as possible?

[Dino]

I just found that 50 amps requires an 8 AWG wire so bypassing the BH it is!  I guess that means I need to find the splice huh?...  

Edit:  I just remembered the violet wire running from the battery stud on the alternator to the horn relay.  Do I keep it on the alt or run it to the starter relay?

[Pete in NH]

I think when you look at the surface area on those Packard 56 pins that actually engage with the opposite pin, anything more than 20 amps is being very optimistic at best. Chrysler got away with running more current than that through them but, it wasn't good practice.

8 gauge is better than 10 and if that's what the maxi-fuse holder uses, I would go with the 8 gauge and get as close to that splice as possible when connecting it in.


Wiring that violet horn relay wire directly to the alternator output stud wasn't really a good practice. When I looked at 69 wiring diagrams , sure enough that's what they did to save a few feet of wire. You can keep it there but I would put a small 5 amp fuse in the line close to the alternator. If you run it back to the starter relay I would still fuse it.

[Pete in NH]

Dino,

I went back and took a second look at my not so great 69 wiring diagram. I though it didn't make sense to run just the control wire to the horn relay from the alternator output stud. Sure enough with a second look it was clear that both the horn relay control and the horns themselves are powered from the alternator output. That being the case you should fuse that line with a 20 amp fuse, not a 5 amp one.

[Dino]

Thanks Pete!   

Would it be better to run the wire from the horn relay to the starter relay with the 20 amp inline fuse close to the starter relay, or is this no different than going from the horn relay to the alternator?

Does anyone know where that multi splice under the dash is?  I hope to do this without taking apart too much of the dash.   

[Pete in NH]

Running the wire for the horns from the starter relay or alternator is electrically the same. You might as well save some wire as Chrysler did and run it from the alternator. The difference is they didn't fuse the line which they should have. If for some reason the wiring would look neater if you ran it from the starter relay that's okay too. The fuse should always be placed closest to the current supply point, either at the alternator or starter relay.

I suspect you'll find that splice point wrapped under a bundle of tape in the main dash harness. I'm not familiar with what they did on a 69 compared to my 71. I would find the black wire that used to go to the ammeter and follow it back to the splice.

[tan top]

Thanks Pete!  

Would it be better to run the wire from the horn relay to the starter relay with the 20 amp inline fuse close to the starter relay, or is this no different than going from the horn relay to the alternator?

Does anyone know where that multi splice under the dash is?  I hope to do this without taking apart too much of the dash.  

the main multi splice  from alternator that supplies power to ignition switch , head lamp switch , & fuse box  , then goes to amp gauge . is roughly in this location ,

second picture is how what goes where from the factory splice
 

[Dino]

Thank you much gentlemen.   

I will keep you guys posted on the progress.

[Dino]

You can then just remove the original fusible link connection on pin J.

Hi Pete,

I am not 100% clear on this part.  I understand the original fusible link is redundant when the load side has a 50 amp fuse, but what do I do with the original fusible link?  Do I replace it with a plain wire going from the bulkhead connector to the starter relay?

[Pete in NH]

Hi Dino,

You would just leave the connection to pin J empty. You have already provided power to the car's accessories through the new 50 amp fuse. You don't want a connection on pin J that would bypass that fuse.

[Dino]

Hi Dino,

You would just leave the connection to pin J empty. You have already provided power to the car's accessories through the new 50 amp fuse. You don't want a connection on pin J that would bypass that fuse.

Oh I see.  I had to draw a sketch to see how the wiring would run, now I get it.  Hey that's one less Packard connector I need!   

Thanks Pete!

[Dino]

Hi Pete,

Now that the cold is finally gone, it's time for me to resurrect this little project!

I got a Blue Sea 50 amp Maxi fuse to safeguard everything from the firewall back: http://theelectricaldepot.com/index.php?main_page=product_info&products_id=233

I think it will fit best right above the bulkhead connector.  If I place it on any other flat spot close to the starter relay, I'll hit the heater/air box.  There's nothing but open air above the bulkhead connector so I think that's its new home.  The old bulkhead connector was removed.  I have not installed the new block because I'm not sure how to run the new wire yet.  I still have to trace the black wire that was hooked to the ammeter back to the splice so I can remove it.  I then will add an 8 gauge wire to the splice (not sure how yet), and run that wire to the tach plug in the firewall.  I'm takin a cue from Tan top here and have incorporated colorful artwork!      

8 AWG wire is pretty tough so I think I need to run the two from the fuse holder in a wide loop to the starter relay and tach plug.  I'll have to go around the vacuum hoses but I don't see a problem with that really.

How should I run the under dash wire to the splice though?  Along the existing loom that runs to the bulkhead connector right next to the firewall plug or take more of a straight short cut to the plug?  I think following the loom would be the better option as long as it's not too long right?  Looks like 4 feet or so total but I'm guessing.

The headlight relay mod was also completed.  The power feed comes from the 80 amp ANL fuse under the battery tray (currently laying on its side) and goes to a 30 amp self resetting circuit breaker.  I found these little red boots online and put one on, it's great protection.  I also have one of those mopar starter relay protector shields.  After all this work I'm not going to risk hitting anything with a wrench and cause trouble.

Still a long way to go but I'll get there.   

[Dino]

Headlight relays

[Pete in NH]

Hi Dino,

Looks like things are coming together nicely and your planning is paying off. Yes, it's nice to see some warmer weather here too. It was the coldest winter in the 15 years we've been here.

Yes, I would run the new feed wire to the splice joint along the existing wire loom as that will keep it secure and tied down. I would just use some tie wraps every 6 inches or so. The four foot run of #8 won't be a problem at all. One of the advantages of using heavy wire is that the voltage drop will be very small even with heavy loads. If the factory wasn't trying to save money they would have used heavier wire in the whole charging system.

[Dino]

I usually don't mind winter but this one was really testing my limits.   

I went back and measured the outside diameter of the 8 gauge wire and it's 1/4".  I then popped the tach plug out of the firewall and measured the hole: 0.24"

Since I'll install a tach eventually, I'd like to leave it alone and drill a bigger hole in the dimple just above and to the right of the plug.  I just need to make sure there's nothing behind it.

I also found the splice and I'm happy to report all looks brand new under the original tape.