[whiteman_01]

Hey, i just noticed that my v70 has no brake lights. It comes out of park fine, the fuse is good, and i have no bulb out warning. All other lights work fine as well. Am I looking at replacing the relay for the brake lights? If so, is it in the same spot as the fog light relay?

Thanks!

 

[BEJinFbk]

There is no relay. Check your fuses ( #11 ) and brake light switch.
There is a lamp out module between the switch and the lamps,
but it's just reads current and shouldn't be a problem.

 

[LloydDobler]

I don't know if they use the same technology but on my last 940, the lights out detector failed and caused this exact problem.

 

[whiteman_01]

Ok, i checked the fuse again, its good. The brake switch, im not sure, but if it was bad, wouldnt that keep the shifter from unlocking from park?

 

[JRL]

Yes
Try a new brake switch

 

[VolvoGuy50]

Yes
Try a new brake switch

Wait, did that "yes" mean that it WOULD cause the tranny to refuse to allow shifting out of park?

Actually, re-checking my wiring diagrams, the switch has nothing to do with the tranny lock. It litterally only turns the lights on and off. Although, there are a relay in socket 106, but if that failed, other stuff wouldn't work either. The lights are wired THROUGH the bulb out sensor, so if that dies, the lights won't work. It also occurred to me that this could be why my reverse lights randomly stopped working a few weeks ago, even though my tranny switch is fine...

 

[BEJinFbk]

Ok, i checked the fuse again, its good. The brake switch, im not sure, but if it was bad, wouldnt that keep the shifter from unlocking from park?

The brake light switch has two sets of contacts.
( For anyone playng the game at home, that makes
it a double pole, single throw, momentary switch.)

Pins 1 & 2 operate the brake light.
Power comes in on pin 1, the red wire,
leaves on pin 2, the yellow wire

Pins 3 & 4 handle the shifter solenoid circuit.

 

[VolvoGuy50]

The brake light switch has two sets of contacts.
( For anyone playng the game at home, that makes
it a double pole, single throw, momentary switch.)

Pins 1 & 2 operate the brake light.
Power comes in on pin 1, the red wire,
leaves on pin 2, the yellow wire

Pins 3 & 4 handle the shifter solenoid circuit.

OK, but if the switch failed, why wouldn't both halves not work?

 

[whiteman_01]

Well, i ordered a new switch today, so we will see what happens.

 

[LloydDobler]

I recommend doing more diagnostics before randomly replacing parts. Buy a cheap multimeter from Harbor Freight, they do the job well enough for most car applications. They're like five bucks. Then you'll know if your switch is the problem or not.

 

[VolvoGuy50]

I recommend doing more diagnostics before randomly replacing parts. Buy a cheap multimeter from Harbor Freight, they do the job well enough for most car applications. They're like five bucks. Then you'll know if your switch is the problem or not.

This

 

[whiteman_01]

Well, i was actually going to do just that today. I was going to take the switch out and see what i could figure out with it. I had a buddy over and he happened to crawl under the dash before i did, not sure why. But, he said the switch wasnt seated in the bracket properly. Whatever he did to the switch im not sure, but i have brake lights again, every time. I was looking at it the day before, and i would get the lights to flicker, but not stay on. So for now, it seems ok.