Headlamp +12v provision

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   What is the circuitry flow to headlamps in an Eagle? I'm trying to trace the cause of voltage drops and I'm suspecting a point of failure somewhere in the dash.

CY, EY and DT are the primary 12v connections for the whole car with CY and EY sharing an eyeloop. CY goes to IGN, EY powers the headlamps. DT is a big snaking wire that directly powers the charge loop, hoodlamp, horn relay, starter solenoid, coil trigger, and ignition primary. It continues on to power the trailer harness, rear defogger, radio, back lamps and literally the rest of the dash. What I want to know is the specific circuit for powering the headlamps and figure out a solution to prevent voltage drops because that one connection is ridiculous.

I assume it is going from the battery to the bulkhead, to the headlamp switch, to the bulkhead, to the headlamp kick(breadboard), bulkhead again, back to a mystery 12v supply, to the bulkhead and out DU/EV for low/high beams. Is this correct?

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DaemonForce Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070	Post Options Post Reply Quote DaemonForce Report Post Thanks(0) Quote Reply Topic: Headlamp +12v provision Posted: Oct/26/2017 at 9:50pm
	What is the circuitry flow to headlamps in an Eagle? I'm trying to trace the cause of voltage drops and I'm suspecting a point of failure somewhere in the dash. CY, EY and DT are the primary 12v connections for the whole car with CY and EY sharing an eyeloop. CY goes to IGN, EY powers the headlamps. DT is a big snaking wire that directly powers the charge loop, hoodlamp, horn relay, starter solenoid, coil trigger, and ignition primary. It continues on to power the trailer harness, rear defogger, radio, back lamps and literally the rest of the dash. What I want to know is the specific circuit for powering the headlamps and figure out a solution to prevent voltage drops because that one connection is ridiculous. I assume it is going from the battery to the bulkhead, to the headlamp switch, to the bulkhead, to the headlamp kick(breadboard), bulkhead again, back to a mystery 12v supply, to the bulkhead and out DU/EV for low/high beams. Is this correct?
	1971 Javelin SST American 304 2v \| FMX \| AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI \| 1982 NWC T-5M (4.03/.76) \| Dana30IFS/35-2.72

nickleone Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Oct/04/2008 Location: westminster co Status: Offline Points: 1446	Post Options Post Reply Quote nickleone Report Post Thanks(0) Quote Reply Posted: Oct/27/2017 at 3:14pm
	I don't know the answer. But I used relays to power the headlights on my ProRaly SX/4. Use the switched power to the headlights to power the relay and a fused connection to the battery. I had 100w headlights in the SX/4 plus another 4 100w driving lights. No voltage drops. Nick
	nick 401 71 Gremlin pro rally car sold 390 V8 SX/4 pro rally car sold 1962 Classic SW T5 4 wheel disc brakes

DaemonForce Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070	Post Options Post Reply Quote DaemonForce Report Post Thanks(0) Quote Reply Posted: Oct/27/2017 at 5:46pm
	Wow, Firefox just killed my reply again before I could send. Getting real tired of this update. x.x I'm weeding through the old harness and trying to create a new one for the wagon, so any decisions I make here are permanent. There really needs to be a fused bus for accessories and bolt-ins but I can't make that happen yet. When tracing back through the old harness I noticed that the ignition box had its own dedicated relay for SW/ON position. The horn used a 3-pin relay grounded from the horn button contact in the headlamp harness. The foglight accessory harness uses its own mountable relay box and even the defogger runs its own enclosed relay box. No matter what I trace back engine side, there is no relay for the headlamps! All of this 12v flow swapping back and forth through the firewall must be the cause of these drops because it's something I notice from the dash when headlamps go on and off. I get the feeling I'll be splicing into my 12v dedicated primary for the headlamps to get this working right.
	1971 Javelin SST American 304 2v \| FMX \| AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI \| 1982 NWC T-5M (4.03/.76) \| Dana30IFS/35-2.72

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19692	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Nov/01/2017 at 6:32am
	More likely the cause isn't the wiring harness, but a weak ground at the headlight. Electricity actually flows from negative to positive, not the other way around as most people assume... after all, the negative post is grounded to the body! The natural flow from negative to positive is probably why there used to be some positive ground systems. In the grand scheme of things it really doesn't matter if positive or negative is grounded in DC electricity, as long as you're consistent and all components are wired appropriately. Not so sure modern electronics would work so good with the leads switched, but most things like standard light bulbs and electric motors won't care. An alternator probably would since it's basically an AC device that converts to DC, but an old fashion generator doesn't care. I put in new grounds and added relays for the headlights on my car. Got a slight increase in brightness, but did it mainly to save wear on the old 1963 headlight switch, which still functions as it should. Reducing current through it should extend life dramatically. There is some resistance in the wiring due to length and number of connections though. I put my relays right beside the battery, maybe a 3' lead to the passenger side headlights, 6-7' to driver's side.
	Frank Swygert

Lyle Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/17/2014 Location: None Status: Offline Points: 772	Post Options Post Reply Quote Lyle Report Post Thanks(0) Quote Reply Posted: Nov/01/2017 at 7:18am
	An easier way for the accessories is to put a 40 amp relay off the ignition and add a separate fuse block for all the accessories off this right beside your main fuse block. The advantage is you don't have to change your whole wiring system and you get a dedicated accessory circuit that isn't intertwined with your running system. Easier to diagnose problems for me, might not be for others.

DaemonForce Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070	Post Options Post Reply Quote DaemonForce Report Post Thanks(0) Quote Reply Posted: Nov/01/2017 at 9:06pm
	I'm getting interested in creating a semi-isolated buss system for the interior with each dedicated 12v connection and maybe one coming from the IGN/SW. mounted to the firewall. Look at the way the bulkhead connector is assembled and you'll see three of four large slots occupied and emphasizing connection strength through solid independent RED +12v inbound connections. I'm most likely going to rip apart my dash to add connections and switches for my fan controller, rock lights, locker, so it may as well be something I handle from the start, giving it a refresh of new wires. Any ideas on how to make the buss lines easier to manage? I've thought about rails but there's obviously going to be one solid connector until maybe I get a winch or plow bolted in.
	1971 Javelin SST American 304 2v \| FMX \| AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI \| 1982 NWC T-5M (4.03/.76) \| Dana30IFS/35-2.72

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19692	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Nov/02/2017 at 5:54am
	BUSS makes small fuse panels that take modern spade fuses. One power connecting lug, six or more fuses. The auto parts stores usually carry the six fuse panel, have to order a larger one. I use one of those through a relay for my accessories, as Lyle suggested to you. You don't have to use the relay, use the panel as a buss bar. The fuses all tap power from the center, have spade lugs one the outside edges (two rows of fuses). Just leave the fuse out where you don't use a lug, stick in when you want to. I'd run everything BUT the winch or plow from those. You need a hefty connection for the winch and plow, IIRC mine was straight off the solenoid (fender mounted Ford style solenoid). In fact, the winch was powered by a dedicated Ford type solenoid, short heavy jumper from it to the starter solenoid battery connection. Think the plow was too -- two separate vehicles, not one with both, both were Jeep J-10s.
	Frank Swygert

DaemonForce Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070	Post Options Post Reply Quote DaemonForce Report Post Thanks(0) Quote Reply Posted: Nov/02/2017 at 8:02am
	So should I focus on refreshing the wires from the firewall to fusebox? It's really starting to sound like this is much easier.
	1971 Javelin SST American 304 2v \| FMX \| AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI \| 1982 NWC T-5M (4.03/.76) \| Dana30IFS/35-2.72

Lyle Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/17/2014 Location: None Status: Offline Points: 772	Post Options Post Reply Quote Lyle Report Post Thanks(0) Quote Reply Posted: Nov/02/2017 at 12:35pm
	I wouldn't state it's easy but it does make a more reliable system and a system you understand. My take on this is usually do it or don't, piece meal just makes things more difficult in the end. I have two bussman 12 fuse blocks (as mentioned by Frank) in my 69 Javelin, one battery component supply and one for accessories. The harness did not have to be cut up or modified to do this. I would suggest a paper and pencil and mark out every circuit you have and decide what you want to go were as a start before even taking anything apart. Once the plan is made then it is just a matter of marking the wires and then following the plan. I also added two breakers for the headlights as this just lowers the current through the old switch and I upgraded to halogen headlamps.

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19692	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Nov/03/2017 at 4:52am
	The good thing about using relays to power anything, and the old wires to trigger the relays, is that you're drastically reducing the loads on the old wiring. New wire to battery and the fuse block (or relay if powering directly) and new wires from fuse block to whatever you're running. The new wires take all the load.
	Frank Swygert