98 s70 base: intermittent brake lights & dash bulb out light

normtodd · Post by **normtodd** » 07 Mar 2010, 15:56

hello all - frustrating issue on base 98 volvo s70

So I am getting an intermittent bulb out warning light that will quickly flash on and off out of the corner of my eye when i press the brake pedal, which is slowly driving me insane.

I can confirm the brake lights only illuminate about 4 out of 5 times the brake pedal is pressed (its not every 5th pedal press, but about that). ive never lost braking ability, just the brake lights, and when the brake lights do not illuminate, the bulb out warning light flashes on.

Ive checked the fuse and all the bulbs, and they are all check out good.

I was toying with the notion that its the brake light switch under the brake pedal. But that may not be correct if the dash bulb out light illuminates when the brake lights dont work. Which leads me to suspect there is a loose ground somewhere that is causing this.

My question to the group is this...

Does the loose ground somewhere make sense? if so where should I look? Lurking in one of the forums I saw a post (that I cannot find for the life of me) suggesting an intermittent ground fault in the center brake light (which is at the top of the rear view window in an s70) or somewhere else.

is the brake light switch a wild goose chase?

I dont even know where to start

Thanks in advance
NT

nrandolph51 · Post by **nrandolph51** » 24 Mar 2010, 20:18

I didn't see a reply but find myself curious as to whether you solved the mystery.

My wife's S80 has developed the same problem and it's driving me nuts chasing it down. Center-top lights work fine. All bulbs are good. All fuses check fine. Break light work intermittently except for center-top, which, works every time.

Norm

Post by **Ozark Lee** » 24 Mar 2010, 22:24

Slide the high mounted third brake light out and check/clean/bend the connections there. That is a know weak link and it will trigger the the brake light failure - even if it is briefly.

...Lee

nrandolph51 · Post by **nrandolph51** » 25 Mar 2010, 07:00

Thanks Lee,

I'll look there later because I think I've located the real culprit. I found this post later in my search and followed it to a successful test: < http://www.2carpros.com/forum/2001-volv ... 93274.html >

The poster listed the RM15 relay as the problem. I never saw it labeled as such but I did locate an M15 relay and swapped it out as suggested. Viola, It worked!! Now I'm off to the Volvo dealer to find out how much they want for that relay. It doesn't look like it should cost very much, but you know how proud they are of stuff with their name engraved on it.

Now on to the next issue: Miles remaining in tank/Alert message computer screen is out.

Cheers,

Norm