One dim brake light
Thread Starter
Advanced
Joined: Dec 2004
Posts: 93
Likes: 0
From: Charlotte NC
One dim brake light
Has anyone else run into a problem with one brake light showing less bright than the other? The driver's side brake light in my '81 is illuminating only one of the two filaments in the 1157 bulb. The turn signal works, but flashes less bright than the other side.
I replaced the bulb with a new one; no change. I swapped the passenger side bulb into the driver's side outlet; no change. The bulb from the driver's side (now in the passenger side) illuminated both filaments, so I'm sure it's not a bulb problem. I cleaned out the outlet and compared it to the other outlet; no obvious difference in appearance of the contacts. I checked the condition of the three wires to the driver's side outlet; no sign of cracks or deterioration.
I have not examined the brake switch over the brake pedal yet; doing that after work tonight.
I searched the posts on the Forum, found several posts on brake lights, but none related to a dim light.
Any suggestions would be greatly appreciated.
GT1981
I replaced the bulb with a new one; no change. I swapped the passenger side bulb into the driver's side outlet; no change. The bulb from the driver's side (now in the passenger side) illuminated both filaments, so I'm sure it's not a bulb problem. I cleaned out the outlet and compared it to the other outlet; no obvious difference in appearance of the contacts. I checked the condition of the three wires to the driver's side outlet; no sign of cracks or deterioration.
I have not examined the brake switch over the brake pedal yet; doing that after work tonight.
I searched the posts on the Forum, found several posts on brake lights, but none related to a dim light.
Any suggestions would be greatly appreciated.
GT1981
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Brake pedal is common to both so thats not the problem. Clean the where it contacts the bulb sleeve for ground and follow the ground wire and make sure it is good, its probably corroded at the terminal at the socket or on the frame
Racer
Joined: Feb 2007
Posts: 271
Likes: 25
From: Buena Vista Colorado
Theandies is right: bad ground. Pull the black ground wire out of the light socket in question and you will likely see a corroded springy brass lug on the end that may be broken at the end where it is bent over. Did a temporary bubba with a small piece of solder wrapped around the lug's tip and jammed it back in the socket. Have not yet found a replacement lug, but it's still working OK after 3 months.
Instructor
Joined: Apr 2006
Posts: 117
Likes: 0
From: Brattleboro Vermont
as i said before my post was wiped out im a tec for penski an run into all types of wire problems and like i said bad ground start at the rear lights an check an clean every ground an wile your at it check for broken wires an check the frame to body grounds vettes are known for ground problems but thats just my two cents 
Thread Starter
Advanced
Joined: Dec 2004
Posts: 93
Likes: 0
From: Charlotte NC
My thanks to everyone and your suggestions so far.
I pulled the black ground wire from the light socket. The bent brass lug is not corroded, broken, or bent flat. The bare wire end at the lug also looks intact and making a good connection to the lug. Before I start checking other ground connections, I need to compare this brass lug to the lug on the passenger side (to see if there is any significant difference).
While I have the lens pieces off both brake lights, I'll compare the filament illumination (one or two filaments glowing with the brake pedal pressed). If only one filament is activated on both sides, then I'm guessing there could be a problem with electrical flow to the filament on the driver's side (causing it to be less bright than the other brake light). This could still be caused by a ground connection problem...
I pulled the black ground wire from the light socket. The bent brass lug is not corroded, broken, or bent flat. The bare wire end at the lug also looks intact and making a good connection to the lug. Before I start checking other ground connections, I need to compare this brass lug to the lug on the passenger side (to see if there is any significant difference).
While I have the lens pieces off both brake lights, I'll compare the filament illumination (one or two filaments glowing with the brake pedal pressed). If only one filament is activated on both sides, then I'm guessing there could be a problem with electrical flow to the filament on the driver's side (causing it to be less bright than the other brake light). This could still be caused by a ground connection problem...
Safety Car
Joined: Aug 2001
Posts: 4,883
Likes: 11
From: North Easton Mass
All of the tail lights/brake lights have ground wires connected to the frame. After 25+ years it's amazing that ANY of the lights still work. If you look under the car you will see the wires. You have to remove the screws, clean the metal until it's shiny (both the frame and the lug) and reconnect everything. Remember that an electrical circuit has to complete a path between + and - . If you only clean the + side you aren't going to fix the problem.
Rick B.
Rick B.
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Intermediate
Joined: Aug 2007
Posts: 38
Likes: 0
From: dallas ga
All of the tail lights/brake lights have ground wires connected to the frame. After 25+ years it's amazing that ANY of the lights still work. If you look under the car you will see the wires. You have to remove the screws, clean the metal until it's shiny (both the frame and the lug) and reconnect everything. Remember that an electrical circuit has to complete a path between + and - . If you only clean the + side you aren't going to fix the problem.
Rick B.
Rick B.
I had a Citation come in (remember them?)one time with the complaint that when putting the vehicle in drive(automatic)the motion of shift lever caused the dome light to dim momentarily then brighten .The solution to fix the problem was grounding the engine and subrame to the body of the car,I ran a wire from a bolt on the engine block to the firewall and voila problem solved,this after an hour or so of head scratching time, if I remember I also had to install a new regulator inside the alternator(not sure if it failed due to the ground problem or not).
