head light on and off

[brackie1]

Noticed the other day that my left head light on dim was not working. Check grounds, no problems. Checked power with probe. Had power when on high beam but none on low beam. I checked both sides of the connector, no power on low beam. Thought well crap I don't want to take the dash off to check switch because it is difficult to get the switch back on. So I am driving it last night and I go over a slight bump and the low beam came on. I went over another small bump and it went off. Hit another and it came back on. Apparently something not connected properly. I have never done anything to the head lights. I have checked ?everything I know to check except the switch. The bumps were barely enough to be noticed. Up until last week the low beam had worked. Any ideas?

[spider2081]

I would check the headlight bucket pigtail connector. I think it is in the engine compartment near the grounding spider on the fender well. Also the lo beam fuse in the fuse box.

[azruss]

sounds like your low beam filament has a break in it and when you bounce, it makes a momentary connection. Take a very close look through the lens.

[baltobernie]

Don't know what year your car is, but in many Spiders the left and right Low beam circuits have their own fuses. The Left is usually fuse "E", 8A. Remove it from the box and clean the fuse ends and contacts with a pencil eraser. You may need to bend the tabs together slightly to provide the correct tension.

[brackie1]

Thanks for the good posts. I had already identified the fuse and checked. It was good. The post about the broken filament sounds like a good place to look. Has anybody tried the replaceable bulb head lights.

Gene
North Carolina

[brackie1]

Oh on the pigtail post. If i read the electrical schematic correctly one wire is for the high beam and one for the low beam. I did a probe on one wire and had power on high beam there was no power on the other wire either on high beam or low beam. For the life of me I could not find a ground wire shouldn't there be one at the roset

Gene
North Carolina

[aj81spider]

The ground wire is actually at the headlight basket. It is grounded to one of the screws that hold the basket in the car.

I suspect that is not your problem as the high beams work and they use the same ground.

[spider2081]

I mistook your first post to mean you were measuring voltage at the headlight bulb connector. I think you are saying you are measuring it at the headlight bucket pigtail connector in the engine compartment.

Being as the high beam work the ground is most likely good as both hi and lo use the same ground. My 1981 ground is made at the grounding spider on the fender well near the pigtail connector.
There is a separate fuse for the left and right lo beam are u sure you are checking the correct fuse.
I would agree the most likely cause would be the bulb itself except you are saying you have no voltage at the 2 pin connector for the light bucket.
For my 81 the wires colors on the bucket side of the pigtail are Grey for lo and Green for hi. For the car side of the connector the wires have a black stripe on them. Are you sure you have the correct connector.
To change the bulb remove the screw in the bottom of the chrome dress ring and then the dress ring pulls off.
Losses the 3 small screws that hold the bulb retaining ring enough to rotate the ring for removal. Once that ring is removed the bulb pretty much falls out.

[GeorgeT]

Possibly a loose or bad connection in the high/low beam column switch.

[baltobernie]

Thanks for the good posts. I had already identified the fuse and checked. It was good. The post about the broken filament sounds like a good place to look. Has anybody tried the replaceable bulb head lights.

Yes, but solve the wiring problem first. Before tearing apart the dash, buy a cheap $10 sealed beam, plug it in and drive around for a while. Careful with those tiny Phillips headlight ring screws; use the correct size screwdriver + PB Blaster. Bugger up those threads, and you have to replace the bucket.

[brackie1]

Had thanks for all the help on a seemingly minor problem. I will go get a new sealed beam and see what happens.

Gene
North Carolina

[azruss]

before you buy a headlight, you can bench test the bulb with a battery charger or a battery. connect across any 2 leads. I think the center one is ground, so each will light each filament. It you dont get ground then both filaments will light up a little dimmer. did you have any luck looking thru the lens to see if one of the filaments was broken. need to look close to tell. it is also worthwhile to change from sealed beam to Halogen. Same look but more advanced bulbs. The vendors as well as speed shops carry Halogens in the old school 7" round style.

[brackie1]

Have looked at the filaments but just can't tell anything. I will take out and bench test it but I think I am just going to buy new halogens.

Gene
North Carolina

[brackie1]

Good morning. I finally got around to looking into my headlight problem with regard to the dim beam not working. I took the headlight out and bench tested it. I working fine so I am ruling out a filament problem. Since I had it out I went ahead and replaced it with a new seal beam which I tested before installing. Same problem high beam works but no low beam. Went to the pig tail in the engine compartment. Am getting power on the green wire which is the high beam but no power on grey low beam wire on either side of the pig tail. Where would the power for each beam coming from? I would think the dash switch, but would it not affect both sides if that were true? The right side works fine.My next thought is that the problem is in the high and low beam switch on the steering column . My manual says that switch can not be fix and that you have to replace the whole steering column. This surely can not be true. As i mentioned in an earlier post the low beam would come on when going over a minor bump. I have checked the fuse and tightened the holder still nothing. Any advise.


Gene
North Carolina

[aj81spider]

According to the wiring diagram I have the wire is powered from fuse 5. If your right low beam is working it is not the switch. The switch provides power to both beams off a single wire. That wire goes to fuses 5 and 6 (left and right).

Check at the fuse box. You should have power on one side of the fuse (both for fuse 6 if that low beam is working).

If the right side is working it is either a blown fuse 5 or it is a break in the wiring harness after the fuse box. If you have 12 V on both sides of fuse 5 then it is a break in the wiring.