Brake Light Gremlin

[BadQ45t]

I solved the brake light inop on my 1992 Q45 by replacing the fuse (thanks Q45tech) and than all the bulbs (thanks Daedalus). Now the stupid light is back on but the brake lights are working just fine.

What gives???? I hate that message replacing the trip meters.

[greg_atlanta]

Next step is replacing the white plastic bulb socket assemblies..... just order from Scottsdale.

Did you use OEM bulbs or auto parts store bulbs?

[911/Q45]

Sometimes, if you just tighten the Phillips screws on the socket assembly, that solves the problem.

[BadQ45t]

Thanks, I'll try that as soon as it dries out. The funny thing is that the brake lights ARE working.

I'll try playing with those assemblies and than order the part if that doesn't work...thanks again.

[BadQ45t]

And I bought the Sylvania bulbs as per Daedalus' instructions....

[DAEDALUS]

Sylvannia *LL* right? There are multiple filaments per bulb...if 1 burns out, the other will still light I think, which might make it seem like the bulb is fine. I would replace all bulbs again...one at a time to try to figure out which bulb might be bad. Once you find that bulb, check the socket assembly for signs of burning or melting. It hasn't been that long since you last replaced them, so the sockets are suspect as Greg said. They're only about $15 I think from S.I.

[Q45tech]

Just like headlight bulbs the way bulbs fail is an evaporation of the tungsten metal from the filament [the diameter of the tiny wire [in a coil] gets progressively smaller and at the weakest spot finally opens. Before this the current increases slightly. The color temperature of the light changes [gets dimmer and yellower].

Wise idea to change all the rear bulbs every few years. Inspect all the bulbs annually but removal and examination of bottom and socket........that way you can order things in advance and plan.

No bulb that I am aware of has a dual [parallel] filament in the same circuit........there are two independent circuit bulbs in the same glass envelope, however.

The current sensing [light out warning] module is quite sensitive to variations [non oem bulb quality] to warn you something is wrong........cheapo bulb melting the socket or just a bad quality bulb [drawing too little or too much current].

I quess I am unusal in that when a bulb is out I stop what I am doing and change the bulb........you do carry a complete set of spares don't you along with fuses, relays, circuit breakers. When you carry spares things don't fail.

In 13 years never had to change a fuse but I periodically pull them all to check for corrosion on terminals.....pulling them, cleans them by the terminals wiping action.

[BadQ45t]

Yes, I bought the LL sylvania bulbs, they are all in very good shape and were just replaced and have less than 1k of driving on them. I tightened up all the screws and took each bulb out and re-inserted it. They are all in perfect shape and the brake lights work just fine, including the upper light. The only problem is the damn sensor not going away.

Should I try new bulbs again???

[greg_atlanta]

If you try new bulbs, get them from dealer.

[reggiegsd]

"........you do carry a complete set of spares don't you along with fuses, relays, circuit breakers. When you carry spares things don't fail."

Since owning British sports cars in the '70s, I always carry a full tool bag. As long as I had that tool bag, nothing broke. Leaving that bag at home guaranteed a failed water pump or a bad universal.

That bag has been a permanent occupant of my trunk for 30 years. Its in the Q now.