Need electronics help!

[Kevin M]

Thanks dude.

[Kevin M]

Alrighty, so the harness are all fabbed, plugged in, and everything works super. Pleasantly surprised to see that either there's no momentary loss of ground when switching between beams, or the ballasts hold a charge longer than that interval. No dipping between highs and lows.

Almost.

There's a minor issue with the current harness that causes a pretty undesirable side effect... Fortunately it operates perfectly safely and I can use it until I install the fix as posted below. I need to do a resistance check tomorrow to see if I am going to need a resistor to make it work, but it did turn out simpler than I ever thought it would need to be.

[sperry]

Originally Posted by BAN SUVS

Alrighty, so the harness are all fabbed, plugged in, and everything works super. Pleasantly surprised to see that either there's no momentary loss of ground when switching between beams, or the ballasts hold a charge longer than that interval. No dipping between highs and lows.

Almost.

There's a minor issue with the current harness that causes a pretty undesirable side effect... Fortunately it operates perfectly safely and I can use it until I install the fix as posted below. I need to do a resistance check tomorrow to see if I am going to need a resistor to make it work, but it did turn out simpler than I ever thought it would need to be.

I could have sworn that your latest drawing was one that I had started with, but I found a problem where the hi beams would latch on, so even after you turned them off, they'd stay on... But looking at your drawing, I don't see anything wrong with it... I guess I had something a little different.

And it doesn't look like you'd need a resistor in there anywhere... it looks right as-is.

What's the side-effect you're having with the current harness? I had some weird ass issues with my fog lights causing my hi-beams to latch on due to the way the fog light switches indicator lamp interacting with a line I had tapped to use as an input for the DRL switch I made.

[Kevin M]

I think the first drawing did would work fine, but it doesn't isolate teh left and rights sides. Any single component failure could disable my lights entirely, so wehn you posted yours I tossed that one and built the one you drew.

Unfortunately, you guessed it... the high beams lock themselves on. I have to kill the lights to get them back to lowbeam only.

The new schematic should work fine, but I was thinking that if resistance of the high beam shield solenoid is high enough, they may not ground out when I hit flash-to-pass. Other than that they should be perfect.

Thanks for your help dude. I probably would have eventually figured this out (hopefully without killing a ballast) but you definitely sped up the process for me.

[sperry]

There must be a ground path through the dash lights or something that locks that solenoid on. You'll probably have the same problem with your drawing as well... as they look functionally the same.

[Kevin M]

You migth still be right, but I think your harness has a ground loop, as shown in attachment. Once you power the high beam relay, it grounds itself through the power side back to the low beam.

[Kevin M]

This would fix it too, but if I can eliminate a relay on each side, I might as well.

Edit: Maybe not. This one has an issue of two hots going to a single ground in FTP, so there are probably gremlins lurking in it as well.

[sperry]

I see what you're saying.... because the low and hi are both pulled to ground as the hi's are turned off, the hi solenoid latches on through the low solenoid... what's confusing me is how that can happen with the +V on the wires between the two solenoids.

I guess that's why I'm a software engineer, and not an electrical engineer.

[Kevin M]

From what I understand, you can split apart a hot lead as much as you want, it's when you try to run multiple hots to a single ground you can have issues. If you look at your original schematic, you can see how it has 4 hot leads from a single source, but they all go to various grounds without teeing. It operates fine as a circuit, it just has an unintended effect when the high beam is grounded.

[sperry]

Originally Posted by BAN SUVS

From what I understand, you can split apart a hot lead as much as you want, it's when you try to run multiple hots to a single ground you can have issues. If you look at your original schematic, you can see how it has 4 hot leads from a single source, but they all go to various grounds without teeing. It operates fine as a circuit, it just has an unintended effect when the high beam is grounded.

Multiple hots to a single ground should be fine... after all, everything eventually grounds back to the neg terminal on the battery, right?

I think you're thinking of signals... like trying to splice speaker wires... you can splice the signal into multiple signals just fine, but if you try to join two different signals, you can get a mess.

[Kevin M]

I see.

[Kevin M]

So it's finally, really, totally finished. I have constant low beams and high beams when I activate them.

But, the simplified harness I drew today didn't work. The high beam circuit didn't have enough power to activate the solenoids. constant low beams, but no high beam activation. I guess that the ground signal just wouldn't overcome the resistance of the solenoids when the low beam ground was handy with basically no resistance.

So I started investigating. High and low filaments of H4 bulbs have about 3-4 Ohms resistance. the relays I am using have about 65 Ohms. I couldn't measure the resistance of thesolenoids however... since they only close when they have power going through them. I guess I could have measured voltage drop and calculated the resistance if I felt scientific, but I am strictly in engineering mode on this so I didn't care. (Scientists try to understand everything about their experiment; engineers jsut want to make things work.)

So, I decided I would just go back to using a second pair of relays to isolate the solenoid circuit with another lead off of the battery. I am using single fused leads for the ballasts, but I figured on shared fuse for the solenoids is fine, since I don't need one if I lose the other anyway.

My first attempt was pretty awesome. It didn't have any captured grounds... it just worked backwards. Low beams ran the highs and high beams only ran lows. Never did figure out why. So, back to the drawing board... and I finally had the epiphany I had been searching for.

I don't need to use the low beam ground at all. The whole point of the low ground is so you can have it switched off when you use high beams... which I don't want. So I moved the ballast circuit ground from the switched low beam ground to a constant ground. Since the hot feed only works when you move the rotary switch on, the extra ground is redundant. That greatly simplified everything, because now I just had to make the other circuit close the solenoids when the high beam ground was switched on.

Man this was a pain in the ass, but in the end it's worth it I guess.

[sperry]

Can't you can take that hi-beam relay out? Split the hot, run one to power the ballast via a relay as you have already, then let the hi-ground pull the shield solenoid to ground by itself? No need to run BATT to the shield solenoid, since it's just a solenoid w/ low current, right? An no latching issues because there's no ground loop?

[Kevin M]

That's what I initially tried to do, but the current from the Common hot on the H4 plug isn't enough to close the solenoids. If I ran battery power directly to the solenoid and then in to the high ground, it might work... but it works now and I don't have an immediate need for those relays, so I'm not going to bother messing with it.

[kidatari]

[sperry]

Josh, how long were you trolling the internet looking for a place to post that picture?

[kidatari]

Originally Posted by sperry

Josh, how long were you trolling the internet looking for a place to post that picture?

I please the Fifth

It's funny, if you look at Kevin's last diagram, the relay on the right looks like a Mooninite (from ATHF) giving you the finger.

[Kevin M]

Did you see that? I was drawing it as hard as I could.