Very Dim Low Beams

[grslightng02]

My headlights don't want to seem to come on very bright, in fact unless I have the high beam on, they're VERY dim. I suppose the first thing to do would be to buy new headlamps and install them. I also have not yet replaced the wiring, which I know is something that's very important to do. Do you suppose the wiring could be causing a weak connection? or does this sound like bad headlamps?

[paul37]

try checking the ground first.

[yellaopelgt]

FIRST thing to do is replace the headlight wiring on a GT(I am assuming its a GT) If you value your car, its not a fused circut and with bare wires touching, it will go up in flames!!!
The 35 amp alternator in our GT's was never much to brag about to begin with ,and compared to newer cars, the lights are very weak.
My car was a garage queen...and when I checked out the headlight wires....the insulation was pretty much gone. Check out all the connections as you go and you will also more than likely find ALOT of corrosion at just about every connection. That "should" get your lights back to snuff.... You may want to consider a bigger alt down the road as it will increase the brightness considerably.
Do a search... ther are tons of threads on how to do this safely!!
HTH
Joe

[jlthunder]

Back in '84 I had one dim headlight. It was the wiring and that was 24 years ago. Imagine what condition it is in now!! Corroded wiring doesn't conduct electricity very well leading to poor illumination and a fire hazard. Replace the wiring and then install Hella H-4's and it will be a night and day difference(no pun intended). The wires only need to be replaced back to the loom around the connection near the drivers side front shock(I'm going from memory here)

[grslightng02]

Thanks for the suggestions and advice everyone. I'll look at updating the wiring ASAP.

[rrossjr]

Originally Posted by grslightng02 Thanks for the suggestions and advice everyone. I'll look at updating the wiring ASAP.

If not sooner... Seriously, this is almost always a problem with GTs and original wiring. Once you get that cleaned up, you may want to consider upgrading to halogens. I did this recently, and it really makes a difference to my 50 y.o. eyeballs!

Ron in Indy

[West Coast GT]

I recommend all of the following steps (A1 through A4):

A1. Replace all headlight wire from bulbs to the wiring harness near the driver's side shock mount.

A2. Grind or sand the area your ground wires connect to the body. Then seal the wire/screw head/body ground connection with liquid rubber, silicone, or other waterproof pliable sealer.

A3. Replace existing headlamp bulbs with new lights. Traditional bulbs ($11 each) work well and seem to be a lot less expensive than converting to H4.

A4. Replace the headlight relay with the new replacement from OpelGTSource ($45).

This should brighten your night driving, it did for my GT. The difference was amazing.

That addresses the headlight circuit and most of the problems you'll encounter. By doing all of the above you'll be hardening the entire system for the long run rather than slapping a Band-Aid on the immediate problem.

Because my GT's more of a road car for weekends and trips I also attacked the supply side;

B1. New battery
B2. New battery cables
B3. New GM 65 amp alternator with internal voltage regulator (while I did this conversion a bit differently), I recommend purchasing OGTS' aftermarket higher capacity alternator & regulator. It's more expensive, but I would do it this way to save time & frustration.

[Dale .D]

h Keith.I've done all that except the headlight relay.My high beams are fine but my lows are pathetic.Time to call OGTS again.Is it just one of those blug in things under the drives dash.?

[wrench459]

Or we could look at the voltage drop.
With a volt meter back probe the brown wire to the center post negative side of the battery.The reading should be very low <.3 volts or you've got a bad ground connection. You know the one the small phillips screw close to the rad support with all the brown wires.

[namba209]

Originally Posted by wrench459 Or we could look at the voltage drop. With a volt meter back probe the brown wire to the center post negative side of the battery.The reading should be very low <.3 volts or you've got a bad ground connection. You know the one the small phillips screw close to the rad support with all the brown wires.

To assist in finding the wires mentioned above, they are forward of the radiator support and outboard of the MC. On my GT there are two screws with all the grounds for the electrical circuits forward of the radiator.

[West Coast GT]

Dale - Yes, OGTS sends you new modern relay guts. You pull the original relay off of the fuse box located under the dash, driver's side. The relay is held to the fuse box with a single nut on a stud from the backside. In other words, reach all the way forward, behind the fuse box and feel the nut. Remove it. Open the relay hosing, and replace the insides. Reinstall.

Wrench459 - The intent behind my recommendation to replace all of the system components is to avoid fixing a problem today, another one next month, and another one next year. Might as well fix it all, have a reliable system, then be done with it for another 35 years.

I like the voltage-drop idea though. Not for this case, but its good to know where to start looking if its a road-side repair.

[grslightng02]

Thanks for the great suggestions guys. I'm gonna start to tackle the car tomorrow morning and see how many things I can get done. In the mean time my headlights won't lock into place since my cable is disconnected from the lever. While trying to manually lock the headlamp housing in place I smashed my left ring finger between the headlamp and body ! OUUUUUUCH !~

I know OGTS sells a front end rewiring kit that includes the headlamp wiring. But if I want to rewire it myself... what guage wiring should I use?

[BMWonly]

Neil, check the wiring diagrams in your shop manual, seems like they are all 12 guage, different colors.

[yellaopelgt]

When you do re-wire it, it would be smart to buy wires that are close to the original colors to avoid confusion to you....and possibly the next owner(if there is one)
Joe

[namba209]

Originally Posted by yellaopelgt When you do re-wire it, it would be smart to buy wires that are close to the original colors to avoid confusion to you....and possibly the next owner(if there is one) Joe

Good point Joe. He'll need a minimum of 12 gauge for the size and the colors are Yellow, lo-beams, Brown, ground, and White, hi-beams.

[BMWonly]

Exactly, this is the left headlight portion of the wiring ddiagram:

[Dennis Texas]

Originally Posted by grslightng02 My headlights don't want to seem to come on very bright, in fact unless I have the high beam on, they're VERY dim. I suppose the first thing to do would be to buy new headlamps and install them. I also have not yet replaced the wiring, which I know is something that's very important to do. Do you suppose the wiring could be causing a weak connection? or does this sound like bad headlamps?

After reading comments I think your culprit is miswired headlights. The ground is attached to one of the elements instead of the grounding terminal on lamp connectors. It sounds like the high beams are rolled meaning the ground is on the element for the high beam and the positive 12 volts is attached to the ground terminal. Basically what that would do is, with just the high beam on it will make no difference the headlight itself does not have a requirement of polarity it would still see the 12 volts across it illuminating the lamp. When you switch to the low beam the ground is on the high beam element putting both in series and it is trying to turn on both lights with 12 volts or about 6 volts apiece or some combination of voltage.

Reasons I say that are:

You have a good ground or high beams would be dim as well
The relay switches from high to low so electrically it is good.
If it was bad connection (I assuming here both lights are dim) means that both connectors would have to be bad.
All that leaves is a rolled connection on the headlight wiring or the low beam connection on the relay is corroded either internally on contactor or the external connection to the wire harness either way there would be some heat buildup and I believe you would see some lamp intensity changes in light as it heated up.

You can buy a prewired connector for headlights at auto parts replace, it needs it to be safer and use good quality wire. Replace wiring from headlight to the harness by the master cylinder.

[West Coast GT]

Had a small problem develop with the headlights.

high beam,
low beam,
high beam,
no beam.

Called OGTS and found they only had used dimmer relays from their stock of parts cars. So I opened mine up, sanded the contacts, sanded the exterior blade connections, and WOW! Headlights are working like a new car. And switching between high beams and low is crisp.

[grslightng02]

Thanks for all the great suggestions guys. I'll have to try rewiring and making sure they're all connected correct. If the headlamps still are weak, I'll spring for some new lamps too.

[namba209]

Originally Posted by West Coast GT Had a small problem develop with the headlights. high beam, low beam, high beam, no beam. Called OGTS and found they only had used dimmer relays from their stock of parts cars. So I opened mine up, sanded the contacts, sanded the exterior blade connections, and WOW! Headlights are working like a new car. And switching between high beams and low is crisp.

If you think about it, that's probably the first time the dimmer has been opened and looked at. Figure years of operation and the contacts get pitted, just like the points. Same applies to the headlight relay, flasher, and of course the starter solenoid. None of which are hard to open up and check, clean and refurbish.

[wrench459]

I've also seen ants in the contacts. Don't ask me why some people have theorized it from the buzzing,electrical field or black holes
Of course a voltage drop test would nail a connection problem.

[grslightng02]

I opened up the headlight and detached the lamp from the 3 prong wire harness. Upon inspecting the wiring I found what looked like old copper wiring that was very tired and was bare, but wrapped in electric tape. Time to go to the hardware store and buy new wiring. How many feet of each color should I get?

[grslightng02]

I just had my electrician neighbor come over and help me check my headlights. The wiring is only receiving 5.36 volts of electricity. That would explain a lot. Time for new wires!

[Gary]

Originally Posted by grslightng02 ... Time for new wires!

Grade 'MTW' wire or marine grade wire (anything with marine name = $$) has more flexible insulation and will last much longer.

[jlthunder]

I don't know the grade, but I used wire from the conduit from gas stations. I used to work in the field where they upgraded gas stations. The wire is oil resistant and good quality. If you ever see a gas station being upgraded, stop by and see if you can get some of the old wire. It is great.