Volvo 850 GLT Bulb Failur Lamp

wlutz · Post by **wlutz** » 25 Apr 2016, 13:05

The bulb failure lamp on my 97 Volvo lights up when brakes are applied. I replaced the rear bulb failure module, beneath the rear driver side light cluster, and nothing changed. Then removed the park light and the bulb failure lamp is on. So I have confidence that the bulb failure module is ok. Looking at the wiring diagram I don't see another possible cause. It has to be related to the brake pedal being depressed ...but how? Any suggestions? Thanks, wlutz.

Post by **Clemens** » 25 Apr 2016, 13:26

Is it the correct bulb failure module? they make at least 3 differnt ones: 2 brake lights, 2+3rd being a bulb, 2+3rd being led (V70).

i sometimes get a bulb warning before hitting the brakepedal after startup.

Maybe the brake light switch at the pedal has too high of a resistance? Or one Connection to a brake light is corroded somewhere?

crlande · Post by **crlande** » 25 Apr 2016, 13:37

Are you sure the brake light bulb filament is not burned out? On my car applying the pedal and the dash lighting up always meant I had a burned out bulb.

Post by **erikv11** » 25 Apr 2016, 13:44

Two common causes:
- What about the "third brake light" in the center back window, is it working properly?
- Check for corrosion in the bulb sockets, and if the correct bulbs are installed.

wlutz · Post by **wlutz** » 26 Apr 2016, 15:26

It's embarrassing but I was not aware of a third brake light. The wife and I had taken turns pressing the brake pedal and monitoring the two brake lights...our eyes and mind were focused on the two brake lights. I removed the lamp cover then pushed in the middle under the lamp assembly and pulled it off its track. The bulb was fine but there was a layer of grey oxidation on the contacts which I scraped off and reinstalled the whole thing and it works and the lamp fail indicator is gone. Thanks to all and especially erikv11. wlutz

Post by **erikv11** » 26 Apr 2016, 16:33

I have also been stumped by the third brake light. It's like a riddle, once you know the answer ...

wlutz wrote: ... it works and the lamp fail indicator is gone ...

Music to our ears.