96 850 Turbo wagon left and right brakelights are inop but my third brakelight works. It happened out of the blue, one morning when I was leaving for work. The bulbs are good as well as the grounds and I can eliminate any possible corrosion issues because it's an Arizona original car, one previous owner and no accidents. According to the schematic that I have, the common component with the three, besides the brake switch, is a "bulb malfunction indicator". This is not to be confused with the light in the instrument cluster. This actually sends the signal to illuminate the dash light. Nearest I can tell, this is the culprit. Anyone have any info on this part like a location or part #, or am I going to have to go on a snipe hunt? Any advice would be greatly appreciated. It's even worth a frosty beverage or two if you're in Gilbert, AZ!

 

Before blaming the circuit for "bulb malfunction indicator"... Have you confirmed that you do not have power on circuit for brake lights with a voltmeter?

On my non-volvo cars that lost power to brakes lights -- one case was a bad hazard light switch, another case was faulty connection behind dash, and the last case was simply a blown fuse.

The reason the third brakelight works is because it has a direct dedicated circuit to the switch ground on the brake pedal. Because the brake lights are used in conjuction with nighttime rear lights, they use another circuit which is shared with nighttime rear lights.

 

There is a junction on I beleive the left side of the car for the brake lights.Check for power there.

 

It wound up being the bulb malfunction indicator after all. Once I got ahold of a component locator, I was able to find the problem.

 

Cool glad you figured it out.

 

Hi,
Could you elaborate on the procedure you used to diagnose this problem? None of my brake lights are working (all 3 out) but the malfunction indicator is not lighting and the bulbs are good. Just replaced the brake switch to no avail. That was $40 down the drain. Just wondering where else to look. I have 12 volts on fuse 12 on one side but not the other. Other fuses I tested have 12 volts on both sides. Any ideas???

Thanks,
Rob

 

Here is a link to a wiring diagram site check it out.
http://www.volvotechinfo.com/WD123/

 

Little more info on this problem (thanks for the link Tech). My bulb out sensor light is not working either. I have pulled the taillight bulb to simulate a failure and it does not come on. It also does not light when I turn the ighition switch to position 2 without the engine on. I don't know if that is an indicator of anything but it seems odd to me. I also pulled the turn signal bulb and try to get it to trigger the bulb but nothing.
Thanks,
Rob

97 850

 

If the blub failure light is supposed to come on by turning the key (I forget if it does) and yours doesn't come on I would be tempted to say that the bulb in the dash is burnt out.

 

Would that take out the functioning of the brake lights themselves? I think there may be a bulb failure sensor or box in the rear of the sedan somewhere? Anyone know if that is true? Saw it on the diagram Tech linked me to.
Thx,
Rob

 

The dash bulb would not affect the Brake lights.
I do believe the sensor is located in the trunk. But I forget exactly where it is.
Haven't replaced one in a couple of years.

 

You are correct Tech. According to the component locator it is on the left side of the trunk. I will dig around for it later after work. Priced a new bulb malfunction indicator sensor at the dealer and it is going for $145. [:@]Ouch!!!! Hope I can find a used one somewhere. Has anyone ever tested one of these or know the procedure to test it?
Thx,
Rob

 

Open it up and look for a Melted solder joint.

 

Okay, tested the bulb malfunction switch and from 57 to 57r, 57 to 57l, and 57 to 57h I get about 3000 ohms. Checked voltage from 57 coming from harness to bulb malfucnction indicator relay and I have a soldi 12 volts. Can i hotwire those terminals to test and is it possible for the switch to test okay with an ohmeter and still be bad? This is a pricy little bugger and even the wrecking yards want $100 for it.
Thanks all,
Rob

 

PS- no volatge at the brake light terminal of the bulb with the relay malfunction thing plugged in.
Rob

 

Sorry, meant 54 r,l,and h. Not 57. Also, Tech, in a previous post you said it had been some time since you replaced one. Mine was a blue box with one wire junction going to it clipped on the metal post below the left light cluster in the rear. says "lamp control 12v" on the exterior of it. part #5kg 005 311-04 I guess this is the item you were refering to.
One last thing, on the brake switch on the pedal I am getting a little over 11 volts and at the wire to 54 I have a full 12 volts. I assume this is all right.
Thanks,
Rob

 

Guys and Gals,,, this thing is killing me. I have replaced all three bulbs (left, right, center) and still no go. Found the plug going into each light cluster and have 12 volts there on both sides but not at the bulbs. Have cleaned contacts, etc. on bulb holder. How can I have 12 volts going into each taillight cluster but no lights for the brakes? I have taillights, reverse, turn, even rear fog. I am about to go crazy with this. Even pulled the ground wires and cleaned and sanded all of them in the trunk. This is nuts!!! Any ideas before I torch this thing??? I am at my wits end and about to bite the bullet and take it to a shop.
Help please,,,,,,,,,,,,,,,
Thanks,
Rob
97 850

 

Problem resolved!!!! Turns out the center light had a broken contact in the module that has the lens in it. I guess someone never saw this ( I was pissed tonight and digging deep) and never noticed the base contacts had voltage but the third brake light plugs did not. Someone broke off one of the tabs partially so I cleaned and bent it and VOILA,,, light from the center. The left and right I brought in the house and scraped and cleaned all contacts and changed all bulbs and guess what,,,,,,,,,,, lights!!! Weird thing is they never looked corroded to start with. Just goes to show. As for the bulb malfunction indicator not working, my guess is the same guy the previous owner had swap the dash cluster for a broken odometer (using a junk clsuter with trip computer that the old cluster lacked,,,, thus no temp display for outside) problem pulled the bulb for the bulb out light since they could not track down why it was on. Remember that broken tab on the third brake light???[:-]

Sorry to have ranted about this so long and thanks to all that responded. I will pull the instrument cluster this weekend if time permits and changed the burnt out bulb near the speedo and see if that bulb out light has conveinently been removed. [>:] I now have a freshly resoldered bulb out malfunction relay and new lights all around for the brakes. Now if I can find a trip computer switch to go with the instrument cluster I can solve that issue too this weekend. Then on to the oil trap and the possibly blown RM seal. [&o]

At least I am making progress.

Thanks again all who responded.

Sincerely,
Rob