Dim CR headlights

[CobraEd]

My headlights seem a little dim compared to other generic cars. I was thinking of going to some of the aftermarket halogens, but wanted to understand why they are dim in the first place. Is this due to small gauge wire being used in the CR harness. Is there anything simple I can do? Is this a common problem. If I go with hotter aftermarket bulbs, I will pull even more amps and could aggrevate the problem further. They are not terrible, just slightly dimmer than the average car.

Does anyone have any similar problems with their CR, or any proven solutions?

Ed

[dkjos]

I have a book written by the Jacobs ignition guy that has a section on wiring headlights for max brightness. If you would like the info, send me a fax number.

dkjos@minnair.com

[Double Venom]

Ed,

I've noticed this on all the Cobras, not just CR's. I think it's due to the old style filament more than anything. We've changed to Halogens before without a problem, but you might want to check the ground. I don't really like the way all the grounds run back through the harness to the dash. We add at least 4 grounds to the harness and this does seem to help a little.

DV

[CobraEd]

Thanks Dick/Ed,

I guess I will start by adding additional grounds to the headlights and switch to halogen. If that doesn't work, or pulls too many amps, I'll give you a call dkjos to get your wiring info.

Thanks
Ed

[dscott]

I've noticed the same thing and switched to the halogens also. DV makes a good point about the grounds. You can't have enough on a fiberglass car!
Don

[Double Venom]

A little off topic, but if you're building a CR's Cobra right now and you don't have the body on...Use the harness ground for the fuel sender, BUT add your own ground to it!

I can't tell you how many tanks we have dropped over the years because the sending unit had lost its ground!

DV

[wilf leek]

Ed - couple of guys on the UK forum had a similar problem - we went around the houses checking voltages at various points, grounds etc. Turned out the headlamps were just not wired right, There is apparently (and I haven't got it straight in my mind yet) a way to make them work wired up wrong (at the bulb connector), but only dimly. Another symptom of this is that the main beam idiot light glows dimly all the time.
When they got the wiring A1 their lights were significantly improved. Probably worth checking out as it's a cheap fix!

[petek]

I used a Painless wiring kit on my CR Cobra and, like DV says, I put a bunch of chassis grounds all over the place. Grind the paint off the chassis, drill and tap a hole, use a #10 screw (or larger) with a star and flat washer; cover the screw and ring lug with dielectric grease after everything is installed. And yes, I did install a separate "extra" ground for the tank sender

Lights: check the voltage at the light terminals with the lights on. If you've got a bad connection or too small of wire you'll see a voltage drop at the load (the lights in this case). If you want to get real fancy you can then check the voltage from the positive light terminal to the positive terminal on the batter to determine the line drop and from the light terminal ground to battery ground to determine the ground line drop.

[Double Venom]

You guys ARE good!
DV

[Don]

Don & DV:

Is there any special model/part number and/or brand of Halogen lights to use as the replacement ?


............thanks

[cobra427mnsi]

I am having the same problem. Dim head lights and the bright light indicator (blue light) is always on. It goes much brighter when I put the brights on, but it stays on low all the time. I put halogen lights in. It helps but I still have to drive with my brights on and no one seems to notice because they don't flash their brights at me. I have checked the grounds. Seems to be grounded well enough. I will have to check the grounds again I guess.

I also have a problem with the heater blower fan. When I turn it on the voltage guage drops dramatically. The higher I turn the fan (speed) the lower the guage drops. Not only does the voltage guage drop but the temp guage goes up and the fuel guage goes down. I ran a ground directly from the fan motor to the negative side of the battery but it did not fix the problem

[petek]

cobra427mnsi,

Just guessing...

Lights: if you've got the connections to the lamp mixed up you could end up with the ground to the Low beam connector, low beam hot to the ground connector, and high beam hot to the proper high beem connector (and/or swap the high and low beam lines but keep the ground to the low beam lug).

What will happen is that the low beam will look ok, but when you switch to high beam the current will flow through both filaments in the bulb, giving not a high beam, not a low beam, perhaps brighter than low beam but not nearly as bright as a high beam. Also you'll get some current flow back through the high beam leg when the low beams are on.

Suggestion: swap the ground and low beam connection to both head lights and see if that cures the problem. If not, reconnect as before and then swap the ground and high beam. One of the two should get you 99% of the way there. The last part is if it appears that the high/low beams are backwards (after fixing the other problem) swap the high and low beam leads.

Blower motor: If the volt meter on the dash is dropping when you turn on the blower motor it would appear that the positive lead to the dash is also supplying power to the blower motor. Two possible fixes: use a relay at the blower motor, let the dash switch turn on the relay, wire a 12 awg wire from the fuse to the relay and then to the blower motor. -OR- beef up the positive wire to the dash, 12 awg or so.

Disclaimer: electrical problems are VERY tough to troubleshoot without actually putting your hands on the suspect parts ... my suggestions are simply guesses

[cobra427mnsi]

Thanks Petek

I will try what you suggest. I like you build site. I have been following your muffler upgrade project. I even ordered some glass packs for myself. They sound great. Presently, they are being welded then off to be ceramic aluminum coated.

Thanks for all your advice

cobra427mnsi

[Jack21]

Lights. I like European e-code headlights, and have been using them for years. On low beam, the front of the car is bathed in a horizontal curtain of light, instead of two small beams. On high, there is a lot more reach in front of the car. Dan Stearn recommends Cibies'. I use 55/100 H-4 bulbs.

Wired the headlights to support the amperage draw. Lights power goes from battery, through a separate circuit breaker, through a separate relay, to the lights. Lights power (112) in the harness goes through the headlight switch and powers the headlight relay control side.

Also put engine fan, and ignition on their own separate direct from the battery, with their own circuit breaker, and relay.

Grounds are wired to a common bussbar, one under the dash, one on the firewall, then to the battery ground. The frame is grounded for redundancy only.

All wiring joints are butt jointed (bare butt joints), crimped, soldered, greased, and heat shrink wrapped so they don't corrode, or pull apart. Ron Francis Wireworks, and Streetworks have a lot of the parts and components common to most automotive wiring jobs. And then there's Radio Shack for wiring supplies.

Ron Francis has Brite Lites, which are higher wattage turn, stop, tail, and parking lights. Car is a lot more visible with those small Lucas lamps.

CobraEd, I have a spare set of Hella Vision Plus's if you'd like to try them out.

[Robert T. Faust]

I too have dim headlights. My problem is due to the fact of low voltage. When I turn on my headlights and check the voltage (at the wiring harness on the firewall) at either low beam #142 or high beam #144 wires, it is only 10 1/2 to 11 volts max. Yet at the relays under the dash I have a full 12(+) volts. So, my source is a good, proper voltage, yet my target (headlights) is low. I've checked and reran all grounds, and have no other "low voltage problems". Cannot find any loose or "barely making contact" connections. I've spoken with another "Club Cobra" member who was able to help me out with some other wiring problems. If I can't find my cause of low voltage, I'll probably use the wiring plan that John said he used.
Bob Faust
Redwood City, CA

[petek]

Bob,
Your low voltage really sounds like line loss (voltage drop in the wires leading to the head lights). Take a 14 awg wire and place it in parallel with the current head light low beam wire and see if the head lights get brighter.

[427sharpe]

You can buy H4 lenses and bulbs via JC Whitney pretty inexpensively. I use the plastic 7" lens (direct replacement) and use their super bright bulbs--I believe they are 100 watt high and 85 lo, compared to 80/55 in a H6054 halogen. They are EXTREMELY bright, especially on hi. I guess thats why they call them 'paint burners'...cause they will scorch the paint on the car ahead if you leave them on.....I also reccommend the small 12v landing light as a driving lite--they are bad to the bone, and will illuminate 1/4 mile ahead! I bought a set of theses at an aircraft supply house in Denton Regional Airport for 50 bucks (pair). They are small, about 4" diameter, with a rubber housing and a single bolt mount. They sales guy said they were Cessna landing lites, but I don't know for sure.

[petek]

427sharpe,
Sound like great bulbs, but they won't solve a dim bulb problem when the issue is too little copper between the battery and the bulb.

[david willyard]

i had the same problem, also used the jc whittny bulbs, but that does not do the trick. I put 2 relay switchs in line, one for the high beam 1 for low beam. I toke a hot wire right of the altenator to the relay swithes then spliced the into the headlight wires, thus no voltage drop that you get from the power going through the dash and light switch. Works great, I now have all the power and more. Even on low beam I still get people giving the bright lights. Don't forget to put in a fuse between the altenater and the relay swithes. It worked for me.
Dave.

[CobraEd]

So in the Classic Roadster, does all the voltage go directly thru the switch or is there a relay driving the bulbs? I have never fooled with it so I do not know.

Ed