The patiant is a 91 240. The symptom is very llittle brake light when the tail lights are on. I thought grounding problem and tightened the ground screws - nothing. Pulled the bulbs and sockets out and cleaned all contacts - nothing. Checked voltage on brake terminal with wifes foot on the pedal while lights are on - 11+ volts! Why are the lights not fully illuminating??? Checked the forums and don't see this problem having occurred before - guess I am just lucky. Any suggestions most welcome. Perplexed in Pennsylvania!

Sorry - should have mentioned also that middle windscreen brake light works just fine with apparent full illumination. Probably the only thing that has kept the tailgaters from smashing into me...

You see 11 volts at the actual circuit board of the bulb sockets? If so you might have the wrong wattage of bulbs. They are 21w, # 1157

Apart from Robert240 suggestion to check the wattage of the globe - sometimes globes aren't as good as they appear to the naked eye. The bulb could have lack of gas, a poorly connected filament etc. so I would substitute a known good bulb for the one that is not working correctly and see what happens.

If the good bulb does exactly the same thing then the fault is somewhere within the globe holder or earth connection.

On my 240 wagon you can actually access the contact in the globe holder that goes between the connecting lug and the globe filament. If it shows 12v or near at this point then you have a faulty earth connection.

To verify this, use a piece of wire with an alligator clip on one end. Connect the alligator clip onto to a known good earth and then firmly make contact with the other end of the wire to the earth contact in the globe holder.

If the lamp then lights up you know what the problem is - and it is just a matter of discovering and eliminating the location of the fault by ensuring all connections are tight or, sometimes it might be necessary to carefully examine the bulb holder and earth wire to establish just where the poor and/or corroded connection causing the problem is.

Good luck!

Is this a wagon or a sedan? In the sedan, the brake light holders are different for each side. White on the right and black on the left.

Make sure no-one has fiddled there before you and crossed over the stop & tail light power wires where you have a dual element globe?????? Mine are 21w/5w globes, and the taillights are the 5w's and stopsare21w. Crossing them would be very dangerous, bu tit would not be a factory fault, it'd be someone fiddling-look for joins etc. NEVER use or trust twisted wires and tape!! All joints MUST be crimped, or soldered & insulated. Heat shrink spaghetti works well from a hair dryer. I have one dedicated for that & other mechanical purposes. Could just be bad globes too, or if dual element, no earth? CHECK!!!!!!

I would replace both brake light bulbs with the same make as different manufacturers bulbs can differ slightly in power and lead to problems.

Thank you all for the great advise. After giving everything a good going over again with your tips in mind and new bulbs in hand with no progress I have opted to install 2 new tail light assemblies and be done with it. I saw many 'small' issues that lead me to believe that even if I fix this problem (what ever it is), another problem is inevitably around the bend. The circuit board on the passengerside developed a wrinkle, a socket hole had a chip that left only 2 socket tangs getting a decent grip and the wiring plug clip was broken off on the left light. If whole new assemblies don't do the trick I will be at my wits end! Hopefully they will come in the post shortly and all will be right with the brick. Thanks again, Dan

Hope it sorts it for you Dan. Let us know the outcome when you get your new bits on

Sure enough the gremlin has been sent packing. I am glad the problem is fixed but I would give $10 to know what it was... Thanks again for all your input guys! Dan

Nothing like the satisfaction of sending those gremlins hopping.

However if I were you, now the annoying things are off the car and don't affect it any more, in my spare time I'd have a closer look at those assemblies because the slightest, silliest things can upset the apple cart in auto 12v DC electrical systems.

And also an added bonus is that, if you do succeed in finding and eliminating the fault, you will then have a tail light to keep as a spare or sell on to someone else.