[mihomes]

Tonight my neighbor informed me both my brake lights were out. I think this is the third time in the past year I have replaced them. None of the other lights in the housing have been a problem - reverse, turn, etc just the brake.

What the heck could be causing this!? I took a quick look at the relay box tonight in the dark and didn't notice anything, but will look again tomorrow. The times I replaced the bulbs prior I didn't notice anything out of the ordinary either.

There is no way these should be going bad this often. I had no problems for 8 years and now they last a few months!

 

[art_arev]

Are you sure you are using the correct spec bulbs? Are you buying proper quality bulbs?

 

[mihomes]

Are you sure you are using the correct spec bulbs? Are you buying proper quality bulbs?

Sylvania 7506

Actually that is the same bulb used in the 3rd brake light in the center as well as the reverse indicator which don't have any problems.

 

[RJV]

Just a long shot ...

I'm wondering if your voltage regulator is about to fail and your alternator is, occasionally, putting out too much voltage. My theory is that the brake light bulbs are often one of the first bulbs/devices to fail when too much voltage goes through the system - because they are used a lot (night and day), cycle a lot in traffic, and the bulb filament work hardens and become brittle and are disposed toward blowing when too much voltage is applied. I do know that turn signal bulbs also have a tough life but my theory doesn't go this far!

If you have a digital volt meter, with engine running, check the DC voltage across your battery terminals .... should be about 13.8 volts DC.

Then with engine still running check the AC voltage across your battery terminals ... should be about 0.05 volts AC, but no more.

If the DC reading is high or low, or the AC reading high then the problem may be a failing voltage regulator.

Another possibility is that you have a bad/intermittent ground on your brake circuit causing the brake lights to flicker - you may not see this unless you are driving behind your own car. If the bulbs flicker then they are heating/cooling/heating rapidly which shortens their life. With your digital volt meter you could test the resistance between the ground terminal in the brake light bulb socket (with bulb removed) and a good known ground.

 

[mihomes]

Just got back from outside... pulled out the housings and checked the bulbs... they are fine and seemed to be snug. I pulled them out of course to double check the # then put them in. Turn the ignition on and they both work fine. So now I am really clueless as to what the problem is. I am pretty sure they were both in the socket snug before pulling them out and I also grease all bulbs before replacing them.

I also checked the relay under the hood again being daytime... looks fine.

So... the only other thing I think of is the brake light switch under the pedal, BUT, wouldn't my dash light be coming on to tell me that was going bad? My SRS light is on, but I know that to be a faulty seatbelt sensor in the rear... no other lights.

Any other ideas?

 

[DrX]

So now I am really clueless as to what the problem is. ... I also grease all bulbs before replacing them.

I think you just answered your own question. Why do you grease them?

 

[ou1954]

Grease

I think you just answered your own question. Why do you grease them?

I have no problem with someone greasing bulb contacts.

Unless it is heavy wheel bearing grease which doesn't flow enough to allow contact, grease will prevent corrosion of the contacts. Makes good sense to me.

 

[mattml430]

The problem with greasing electrical parts they will attract dirt and dust and then possible bad contact. Get some spray contact cleaner and give them a good clean.

 

[mihomes]

I have to disagree as well. So you're telling me the bulb grease caused both the brake bulbs to stop working and then start again exactly at the same time? All the other bulbs are greased too which haven't had problems.

 

[ou1954]

Grease

I have to disagree as well. So you're telling me the bulb grease caused both the brake bulbs to stop working and then start again exactly at the same time? All the other bulbs are greased too which haven't had problems.

I have to go with the OP. I don't see how grease could allow dust to get between contacts under pressure.

I do see how a lack of sealing could allow moisture to get there and cause corrosion with the two different types of metal, lead from the bulb and some plated socket contact.

In any case, if a group of bulbs go out at the same time, the quoted comment above makes good sense.

Finally, grease will help protect flashlights and other devices that use dry-cell batteries from corroding the contacts when the batteries start to leak.

I go with grease

 

[RJV]

I have to disagree as well. So you're telling me the bulb grease caused both the brake bulbs to stop working and then start again exactly at the same time? All the other bulbs are greased too which haven't had problems.

mattml430 didn't say that - these are entirely your words, not his. Read his post #8 again. I have never and would never put grease on bulb contacts. If a light housing is admitting water then I would fix the leak, not grease the bulb contacts. Old wives' tale.

And thanks for allowing me to add my post #4 above to your thread. Totally ignored. If you prefer to ignore advice and poke around with the brake light switch and relay then go for it. Good luck.

 

[DrX]

mihomes, you didn't explain why you grease them, but I've never heard of a bulb failing due to corrosion of a contact.

Grease is nonconductive, and if you get any on the glass envelope, that can cause hot-spots and premature failure. When handling halogen bulbs, for example, you are advised to not use bare fingers due to tiny amounts of skin oil getting onto the glass. It can't be good for ordinary incandescent bulbs either.

This is the first time I've seen this described. Did your father teach you to do it? Don't teach your sons.

So you're telling me the bulb grease caused both the brake bulbs to stop working and then start again exactly at the same time?

If they didn't work before you checked them by pulling them out, then yes.

 

[ou1954]

Grease on bulb contacts

mihomes, you didn't explain why you grease them, but I've never heard of a bulb failing due to corrosion of a contact.

Grease is nonconductive, and if you get any on the glass envelope, that can cause hot-spots and premature failure. When handling halogen bulbs, for example, you are advised to not use bare fingers due to tiny amounts of skin oil getting onto the glass. It can't be good for ordinary incandescent bulbs either.

This is the first time I've seen this described. Did your father teach you to do it? Don't teach your sons.


If they didn't work before you checked them by pulling them out, then yes.

Not sure whom you are trying to insult by the statement but your comment:

"Did your father teach you to do it? Don't teach your sons." would surely have insulted me.

In any case, everyone knows that grease, or most versions, are non-conductive but when you put grease on the base of a bulb it gets displaced by the contact pressure and doesn't cause a problem.

There are special greases, usually metallic-impregnated, used to improve high current connections, but that is not an issue here. If you have any question about that, look up the Trestle Project at Los Alamos or do a Google search on Magneform or ElMag. If you want to discus grease, high current contacts, etc., I am your man, just PM me and I will explain it to you.

The headlamps on most cars now run the halogen cycle to recover evaporated tungsten and do indeed run a hot envelope in order to re-cycle the tungsten that is evaporated from the hot filament. There are specific instructions on handling those bulbs and standard practice is to wipe them with alcohol and not touch them with fingers after they are clean.

If you want to protect your flashlight, the one that eventually dies in your car trunk, or a seldom-used strobe, a little grease on the contacts may save them from damage if the device gets wet or the batteries leak, and even "modern" alkaline batteries will leak at some point.

I hope you will have sufficent self integrity to apologize to the person you addressed in the statement quoted above.

 

[DrX]

That statement simply means, wherever you learned that, stop.

An insult would be: "You grease your bulbs? You're an idiot!"

Apologies for any offence caused.

 

[mattml430]

I have to disagree as well. So you're telling me the bulb grease caused both the brake bulbs to stop working and then start again exactly at the same time? All the other bulbs are greased too which haven't had problems.

Just trying to give you possible causes of your problems as we are not standing at the back of your truck and only going on information your giving us.

 

[ou1954]

Brake lights

Just trying to give you possible causes of your problems as we are not standing at the back of your truck and only going on information your giving us.

I have a very vague recollection of a thread about the brake light on a series 163 car. I think it indicated that the person who started the thread said the brake light switch was damaged severely.

I also seem to recall that the switch was installed by left-twisting it into a bayonet socket near the brake lever under the dash and it was then self-adjusting. [Thinking further back, I believe I had to replace my brake light switch on the ML320. A mind is a terrible thing to lose.]

Does anyone recall that post on this forum?

(It was another forum, perhaps two others.)

Look here for at least one example and scroll down to the pictures. I well remember replacing that switch on the ML320:

http://www.benzworld.org/forums/r170-slk-class/1682719-diy-replace-brake-light-switch.html

 

[ou1954]

Grease

I'd like to ask mattml430, with over 15 years experience in trailer construction including marine applications, if he applies grease to bulbs before or after installation.

DrX, you are consistent in your pursuit. I honor you for that . . .

My 6 Volt flashlight, new from Home Depot, has clear grease on the contacts which connect the switch to the reflector/LED assembly. It didn't get there by mistake. Home Depot doesn't waste money or labor on their items.

I got the light, with the battery, for the same price as a new battery so I trashed the old light and am happy with LED's.

 

[ou1954]

Look here for at least one example and scroll down to the pictures. I well remember replacing that switch on the ML320:

http://www.benzworld.org/forums/r170-slk-class/1682719-diy-replace-brake-light-switch.html

The switch was seriously trashed.

 

[mattml430]

I'd like to ask mattml430, with over 15 years experience in trailer construction including marine applications, if he applies grease to bulbs before or after installation.

Definitely not grease.
In the marine industry we only ever used a light lanolin based spray for electrical joins where they could be subject to salt spray or similar.
No dirt or dust out on the water though. All our air intakes only ever had a thin piece of foam on them that's how clean the environment is in the engine rooms.
I don't like the sound of metal impregnated grease, wouldn't that create resistance between the +/-

 

[ou1954]

Connections

<snip>

I don't like the sound of metal impregnated grease, wouldn't that create resistance between the +/-

Read the posting again, post 13 to be precise.

Metal impregnated grease is used in making connections where very high currents, i.e. 5,000 amps, and more, are involved. Pulsed power systems, etc. Rail gap switches, and more. My experience was with Atomic Bomb EMP (Electromagnetic Pulse) simulators for Los Alamos Labs. We built the pulse generators but did not do the testing.

The material contained in the grease is actually very hard and serves to bite into the pieces being joined. The particles are not always metal, usually something very hard and conductive. It bites into the pieces being joined, often aluminum sheets 1/2" thick, sometimes more. The objective is to LOWER the resistance of the junction.