1990 240dl

no brake lights...

replace bulbs in both sides and 3rd light as well...

Still no brake lights. BUT, I have brake light always on on the pass side, but drivers side is tail only... and 3rd light is nothing...
Fuse good.

Is this just a case of bad boards? Maybe pedal switch?

 

A brake light is working or not? Do you mean you have a rear fog light on one side? (is the switch turned on?) If no lights come on when brake pedal is depressed -

Power for the brake lights goes thru the fuse to the switch to the bulb out relay to the bulbs. If all are not working check the fuse, check power at the switch. The bulb out relays can get a poor solder connection in side and prevent the brake lights from working also. Check for power with your $3 test light from amazon/harbor freight.

 

This is what Im getting as it sits.

taillights work... though after the bulb change the pass side is lit like a brake light...
When the brake pedal is pressed, nothing changes from what you see here. 3rd light does nothing.

the fogs work, but are switched off.

pouring rain today so I didnt dig in an test the brake switch. But ordered one from IPD just in case, for under $10 why not...

Where is it located? I did a quick look around the pedal and didnt see it...

 

Also noticed now that the bulb failure light is on.

 

The left and right brake light bulbs are 1157s in the lower outer lenses. 2 filaments in the bulb. A 5 watt (parking) and a 21 watt (brake, turn signal, rear fog lamp all use a 21 watt filament bulb either a single filament, a 1156, or a 1157 with 2 filaments)

Your right lower outer is too bright with the parking lights on. That means - someone has put a single filament 1156 in, or the wrong bulb holder is being used (the bulb holder is white plastic on the right side and black plastic on the left, the connections are revered in the white holders) or the bulb is installed backwards in the melted white bulb holder or taillamp is so melted the connectors line up in the wrong place.

The bulb out system works by comparing the current used by the left and the right sides. It only cares about the 4 rear parking bulbs, the 3 brake lights and the low beam filaments. If you take 4 parking light bulbs out - the bulb out light will be off. If you just install the 2 inner #56 bulbs of the same brand and age, the bulb out will be off. It's that bright bulb on the right outer causing the bulb failure indication.

The brake light switch is mounted high up on the brake pedal and for some people can be difficult to get to. Much easier to test it BEFORE buying a new part that won't fix the car.

An easy free solution to the outer brake bulbs always malfunctioning (due to melted stuff) - is to switch the wiring in the plug on the back of the taillight - to move (or just disconnect and cut) the wires for the rear fog, and move the brake light wire to the rear fog position. That position is where the brake lights were until 1986.

Then the lower outer only has to work as a parking light and is much less likely to melt as quickly again.

 

I put the old bulbs back in, now the tail lights look normal again.

But, when I put a bulb in the 3rd brake light.... The passenger side tails go out & still no brake lights. Bulb malf. Light stays on

I pulled the bulb out of the 3rd brake Light... No more warning light and both tails are back on. But no brake lights