Re-wiring Required

[70rag383]

Question for the group:

I am running 2 electrical fans that are controlled by the water pump thermostat. When the fans comes on the ammeter displays going into fully charging mode and stays that way until the fans turn off.  Seems normal to me.  When I drive with the headlights and the fans are on, the ammeter goes crazy, like right off the charging scale, the headlights and dash lights flicker from very bright and then go dimmer once the fans turn off.  It's very disconcerting.

Should I be looking at re-wiring the headlight circuit or perhaps any other suggestions to get around this issue.

[Chryco Psycho]

I would run a bypass from the alt to the starter relay so the load doesn't go through the firewall & ammeter circuit , also use relays to take the power from the start realy directly to the fans

[70rag383]

Thanks very much Chryco.  I already have relays for the electric fan circuit.   I assume if I run the bypass wire from the alt to the starter relay:

1. the ammeter will no longer register the correct readings.  Any solutions for this?
2. I will need to include a fusible link on the new bypass wire. 

[Chryco Psycho]

Correct , the amp gauge will barely move once the bypass is in place , you can replace it with a volt guage even on that read voltage in the lighter socket .
I see no reason to put a fusable link in the bypass as you have full power available both from the Alt & the battery , which end would you fuse ??

[YellowThumper]

I agree with Chryco.
What is most likely happening is you are overloading the 50yo blade connector in firewall. When this starts to get hot it will corrode. Corrosion makes for poor connection. So it gets even hotter.
Vicious downhill spiral to failure.
Addition of spare volt guage as mentioned is simplest path.
Your factory guage can be sent out and converted to volts instead.
There was a thread on another forum that showed you can swap in an aftermarket volt guage if you have no issue with modification of factory guage housing.

[Burdar]

Where are you drawing power for your cooling fans?  It was just posted last week that you shouldn't be drawing power off of the battery.  You should be drawing power off of the alternator stud.  This will take that load off of the bulkhead.  If you run a bypass wire from the alternator to the starter relay, you can then draw power from the starter relay stud to power the cooling fans.  It's a good idea to add relays to the headlight circuit as well.

[70rag383]

Yes that is exactly what's happening. the bulkhead connector and connectors were brand new. after 5,000 miles, the connection of the red wire from the battery into the bulkhead became corroded. Lost all power to the car. I cleaned the connection and added  some dielectric grease to prevent it from re-occuring.

[70rag383]

Where are you drawing power for your cooling fans?  It was just posted last week that you shouldn't be drawing power off of the battery.  You should be drawing power off of the alternator stud.  This will take that load off of the bulkhead.  If you run a bypass wire from the alternator to the starter relay, you can then draw power from the starter relay stud to power the cooling fans.  It's a good idea to add relays to the headlight circuit as well.

Hey Burdar, the fans are wired into the starter relay, not directly into the battery.  I think what you are saying is that's ok but I need a bypass wire from the alternator stud to the starter relay.

[Burdar]

That's correct.  By having it connected at the relay WITHOUT the bypass wire, you are sending all that alternator current through the bulkhead connector TWICE.  With the bypass wire you will be feeding the relay with power directly from the alternator.

[Brads70]

What alternator are you using? Stock? If so I found they wouldn't keep up with electrical add on's such as electric fans and eventually depleted the battery.

[70 Challenger Lover]

The bypass wire is definitely worth doing, electric fans or not. I do that to all my cars now. Inexpensive piece of mind. An ammeter doesn't provide nearly as much information as a voltage gauge so another worthwhile mod.

[70rag383]

What alternator are you using? Stock? If so I found they wouldn't keep up with electrical add on's such as electric fans and eventually depleted the battery.

It's an aftermarket alternator so more amp output for sure.

[crackedback]

You are killing the bulkhead connector as Burdar mentioned without a wire around solution.

I build those wires all the time for our mopars.  6 or 8ga wire with a fusible link in it.   Blends in nicely with the OEM harness.

[70rag383]

You are killing the bulkhead connector as Burdar mentioned without a wire around solution.

I build those wires all the time for our mopars.  6 or 8ga wire with a fusible link in it.   Blends in nicely with the OEM harness.

Thanks for the info. Do you recommend routing it via the firewall or via the rad support? How much for yo to make me one?  I'm also interested in taking the headlights off the main circuit and I think you also have a kit for that?

[crackedback]

You are killing the bulkhead connector as Burdar mentioned without a wire around solution.

I build those wires all the time for our mopars.  6 or 8ga wire with a fusible link in it.   Blends in nicely with the OEM harness.

Thanks for the info. Do you recommend routing it via the firewall or via the rad support? How much for yo to make me one?  I'm also interested in taking the headlights off the main circuit and I think you also have a kit for that?

I prefer the factory route.  Crazy as it sounds, the path is just about same length either way. 

Yes I have HL relay kits.  4 Headlight systems are 160 + shipping.  Wire around depending on wire gauge are $30-40.   I do discount for multiple purchases.

Let me know

Rob