67 coronet
Well-Known Member
no one mentioned a good eng to chassis ground. our mounts have the assembly floating on rubber. start with a good eng to chassis ground wire before fighting gremlins.
Headlights are dim
- Thread starter 67 GTX
- Start date
MrJLR
Jeff
- Local time
- 2:03 PM
- Joined
- Feb 12, 2016
- Messages
- 1,460
- Reaction score
- 4,290
- Location
- Menifee, California
I did the CrackedBack relay kit...WOW what a difference!
Jeff
Jeff
That's the picture I posted earlier on just battery power, engine not running..is WOW
67 GTX
Well-Known Member
I completely went through the entire headlight wiring. Checked and cleaned everything.
In the end, I do get 12.6 volts at the headlight plugs (engine off).
Upon turning the lights on, I get the voltage drop across the headlights themselves, which I assume is normal?
When checking my brights with the engine on, I get 10 volts. This may make sense since the other bulbs are also on, drawing away power.
The lights do seem brighter, so even if some issue still persists, I have improved the situation. I think I had some corrosion on some of the headlight plugs, which wasn't helping.
In the end, I do get 12.6 volts at the headlight plugs (engine off).
Upon turning the lights on, I get the voltage drop across the headlights themselves, which I assume is normal?
When checking my brights with the engine on, I get 10 volts. This may make sense since the other bulbs are also on, drawing away power.
The lights do seem brighter, so even if some issue still persists, I have improved the situation. I think I had some corrosion on some of the headlight plugs, which wasn't helping.
Crackedback
Well-Known Member
10 volts at the headlights is not good. That's 3+ volts less than what they should have. Prime reason to install a relay kit.
OEM wiring was barely adequate in 1967, degradation and corrosion take it's toll on items.
OEM wiring was barely adequate in 1967, degradation and corrosion take it's toll on items.
67 GTX
Well-Known Member
Checked again yesterday, getting almost 11 volts at the brights. I realized that last time I checked I had my blower on (and it's warm out and struggles which draws even more power).
But I do agree it isn't as good as new, but I went from 7 to 11 volts at the brights, so at least cleaning everything did make a large improvement.
But I do agree it isn't as good as new, but I went from 7 to 11 volts at the brights, so at least cleaning everything did make a large improvement.
Crackedback
Well-Known Member
That's still probably a 25-30% ish reduction in light output from where it should be.
Wietse
Well-Known Member
I think you will always have a little voltage drop when measuring right at the consumer or not?
If i need to get some access in the head light area and have to remove them i will measure it on my car and see what comes up.
If i need to get some access in the head light area and have to remove them i will measure it on my car and see what comes up.
Crackedback
Well-Known Member
Voltage drop is a function of run length, amp draw and wire sizing.
20+% voltage drop is not an acceptable level. 3% is excellent for drop. The lights with the car running should have 13+ volts at the bulb. Not likely to ever get close with OEM wiring even in exceptional condition.
20+% voltage drop is not an acceptable level. 3% is excellent for drop. The lights with the car running should have 13+ volts at the bulb. Not likely to ever get close with OEM wiring even in exceptional condition.
Crackedback
Well-Known Member
Someone disagrees with that post. hmmm.
Industry standard for drop is less than 10%, I prefer much less than 10% and closer to 5 or less if possible.
Just a wild guess based on 14.3 volts and wire sizing in OEM cars, you might get 13.1ish if everything was perfect. That guess doesn't not account for additional resistance from all the other switches/connections in the run.
Industry standard for drop is less than 10%, I prefer much less than 10% and closer to 5 or less if possible.
Just a wild guess based on 14.3 volts and wire sizing in OEM cars, you might get 13.1ish if everything was perfect. That guess doesn't not account for additional resistance from all the other switches/connections in the run.
Last edited:
Crackedback
Well-Known Member
Fat fingered it. LOL
First, I apologize for the disagree. My phone took a tumble on the concrete and has a oh so slight hairline crack across the display glass. It distorts the rating icons. I will not rate any posts until I get a new screen, or phone (or rate on the PC).
Second, I want to comment that everyone is not thinking about this properly. As an engineer who has worked in the electronics industry almost 38 years, I am always amazed that people often ignore the elephant in the room when discussing voltages across a harness, circuit, etc etc. That elephant is the VOLTAGE DROP. Don't think that a 1V drop still produces good headlight illumination, but think about that 1V drop as creating HEAT. A voltage drop is the equivalent to wear and tear of your circuit. In this particular subject, the wear and tear is the bulkhead connections, and the headlamp switch itself. As corrosion, dirt, grease, etc build across these voltage drops over the years the HEAT increases. As the heat increases the wear increases, and yes, the voltage drop increases.
Nothing wrong with cleaning all of the contacts and connections to reduce the voltage drop. This is the right thing to do and corrects the problem, but the relay addition basically reduces the current load, which reduces, or virtually eliminates the voltage drop from the circuit.
I will be ordering the crackedback kit soon myself. I added the 'police harness' to my Grand Marquis years ago not because I wanted brighter headlights, but that change protects my GEM module from ever burning out. The relay will protect your bulkhead and headlight switch from ever burning as the same sort of fix.
Second, I want to comment that everyone is not thinking about this properly. As an engineer who has worked in the electronics industry almost 38 years, I am always amazed that people often ignore the elephant in the room when discussing voltages across a harness, circuit, etc etc. That elephant is the VOLTAGE DROP. Don't think that a 1V drop still produces good headlight illumination, but think about that 1V drop as creating HEAT. A voltage drop is the equivalent to wear and tear of your circuit. In this particular subject, the wear and tear is the bulkhead connections, and the headlamp switch itself. As corrosion, dirt, grease, etc build across these voltage drops over the years the HEAT increases. As the heat increases the wear increases, and yes, the voltage drop increases.
Nothing wrong with cleaning all of the contacts and connections to reduce the voltage drop. This is the right thing to do and corrects the problem, but the relay addition basically reduces the current load, which reduces, or virtually eliminates the voltage drop from the circuit.
I will be ordering the crackedback kit soon myself. I added the 'police harness' to my Grand Marquis years ago not because I wanted brighter headlights, but that change protects my GEM module from ever burning out. The relay will protect your bulkhead and headlight switch from ever burning as the same sort of fix.
Crackedback
Well-Known Member
No problem... thought it was funny and actually made me think on a Sunday morning which can be a challenge! 
Similar threads
