Driver side brake light problems

[Bullet4x4]

Hi,

I have an unusual problem with my driver side brake light. All of my turn signals work correctly, however my driver side brake light will only turn on if I turn on the left turn signal first. If I turn on my right turn signal, the right brake light will only turn on. To get both brake lights to turn on at the same time, I have to turn on/off the left turn signal first. It will then work correctly until I turn the right turn signal on again.

Would this problem be caused by the brake pedal switch or the turn signal switch on the steering column? Have any of you had similar issues?

Thank you for your help.

 

[rampage]

First things first, do the simple and free checks. Whenever I hear of weird electrical issues like this with brake/turn signal lights it's most likely one of two things - bad/wrong bulb or bad ground.
First, swap the bulbs from side to side and see if the problem follow or stays put. Second, check to make sure the ground for the lights are good and connections are clean. Then report back.

 

[Bullet4x4]

Last week, I disassembled the tail light housing and replaced the bulbs with new ones that tested good with a multi meter. The ground connections appeared to be in good shape. Am I assuming too much to think the ground is good based on the fact that I can turn both brake lights on, but only after turning on the left turn signal first?

 

[rampage]

You are. It could start the current flowing, just always good to check. And the break light bulbs have two filaments, one for brake and one for turn IIRC. Don't assume that because it's new that it's good. That's why I say swap them first so you can narrow the problem. And are you positive they are the same bulbs and that someone didn't put a bulb back in the wrong spot on the rack at the auto store?

 

[diesel4me]

I've had a bad turn signal switch make only one brake light work and the other when it felt like it,but I'd check all other things first,since that is the most difficult thing to replace..(my luck usually runs that way--the worst thing to fix,is what was wrong !.. )

 

[Fastereddie]

Turn signal switch is worn.

 

[diesel4me]

I replaced just about everything on the truck that had the one dead brake light problem intermittently,before I accidentally found out by pulling back on the turn signal lever,both of the brake lights lit up,but if I let off or pushed the lever towards the dash,it would go out!..

This was on a friends old '70 F-350 ramp truck,finding a new switch was quite a chore,and it was $70 ,this was in 1995 too!..

 

[HankScorpio]

Sounds like it is in the switch. When you think of the circuit needed to make the tail and brake light work together it gets weird. How can you keep the light flashing while you step on the brake? They are using the same filament. A relay? A weird logic circuit? No, it's all in the switch. The switch is dirrecting the brake pedal voltage to the taillight. When you turn on the blinker it only sends that voltage to one side and sends flashing to the other side. If you look at the electrical schematic it helps but it is still a bit confusing. Double check all the wiring in the back, double check all the bulbs and then move on to the switch in the column. Turn signal gremlins can be tough to figure out. Good luck!

 

[Emeraldcove]

Had a similar problem on my 79 GMC Crew-cab dually, I had both turn signals working but only one brake light. I ended up using contact cleaner on the plug in connections for the tail lights where the adapter for the trailer lights plugs into the factory harness and made sure the ground on the adapter was landed on a clean ground as well. The Northwest isn't real forgiving on electrical connections on vehicles sitting outside for years. Hope it turns out to be minor if not time consuming.