Hi, Just bought 1987 240gl and found that no brake lights work and it seems the a/c turns on by itself. Changed fuses but no change. Does that sound like Bulb Failure Unit? Thanks in advance for any advice.

 

Make sure the brake button in front of the brake pedal is not stuck down, and jiggle it around. If not, mess around with the connections in the rear lights. These things are notorious for finicky connections.

 

Ok..just checked/reset bulb connections and swapped #7 brake fuse with #9 hazard.. hazards work so at least can confirm not a fuse issue. I also pulled out bulb failure unit wiring and reset.

Going out to get an automotive test light to try to test switch under brake. There are 2 wires plugging into switch. 1 goes to small silver cylinder above brake and 1 ties into another wire. Should they both have power all the time?

 

Hmmm... not sure. Just moving it worked for me, so that's really all I know.

 

No, they should not. Pressing the brake pedal depresses the switch which completes the circuit. Rather than a test light, I recommend buying a digital multi-meter. You'll need it down the road! Oh...and the a/c? Make certain the rotary **** is ALL the way turned clockwise. When my daughter had my 245, that **** never seemed to get completely turned off. She was running a/c even in the winter...

 

I'm thinking one should, and the other not...

 

I thought pressing the brake pedal releases the button? Maybe I should take a look.

 

Most likely your Integrity Sensor (Bulb Failure Relay) it is located behind steering wheel under the knee bolster driver side. You need to reach your hand up there feel for it and disconnect it from it's holster. It's a Big red cylinder...but you can also check your switch that is attached behind the brake pedal has 2 wires running to it. Put those 2 wires together and if your lights come on you know that's your problem but 9 out of 10 times it's the Bulb Failure Relay...If it fails you will have no power to either one side or both. All the testing in the world will have you so frustrated most people do not know about this and they end up splicing wires together and rigging the lights to work...don't be that guy


FAILURE OF VOLVO BULB FAILURE RELAYS
The Bulb Failure Relay is a device that alerts the driver of a failed low-beam headlamp, tail lamp or brake lamp by sensing the balance of current draw between the left and right side lighting circuits. When that dash light comes on, it means the relay recognizes that one side is drawing more current that the other. This usually means there is a bulb out, but occasionally, it can be triggered by incorrect or mismatched bulbs, or even sometimes when one side has a newer bulb than the other.

The red relay pictured at left is PN 1362370, which fits the 1986-93 240, 1986 and later 740, 780, and 1991-94 940. Other variations for 200/700/900 Volvos include a yellow one, PN 1362278 (1978-85 240 and 740 through 1985), another yellow one, PN 3545704 (1988-90 760, 1991-94 940 SE and 960), and a blue one, PN 9128814 (same 1988-90 760, 1991-94 940 SE and 960).

The failure of these relays is becoming more frequent in older Volvos. The symptom of failure can be headlights or tailights (or often just one side) that will not work even after verifying that fuses, switches, headlight relays and wiring are all in good order.

 

Thanks for all the great advise. I ordered the bulb failure unit and hopefully will have a street legal 240 next week.

 

I just finished wiring up the bulb holders to the circuit Mylar. It seemed to have work, but now the problem is the connector from the harness to the lamp circuit. Next thing I will do is just wiring the bulb holders to he harness itself and bypass he stupid Mylar connections. Still have to fix the intermittent problem with he headlights now. Man I just want to rewire the whole car myself.

 

I replaced bulb relay...nothing. Then removed brake light bulbs one at a time again. This time I got the lights to flicker and then stay. I put old bulb relay back in and got flicker then mostly working on that relay as well.

So I went back to switch behind brake. It's black and has button that pushes out when brake is pressed. What I don't understand is while pushing brake down to release button behind pedal I pushed the brake button in and released. The brake lights stayed on. I then unplugged the 2 wire plug going into switch and the pedal still controlled whether brake lights were on...not what I thought to be the brake switch.

Does the black brake switch control the brake lights or the brake arm itself with some switch higher up? My problem now is there seems to be a sweet spot when pressing brake to get the lights to work. If when you first crank it just press on brake there's either a flicker or delay then they come on. There's also a black hose connected to switch. Anyone ever seen anything like this?

 

The switch with the black vacuum hose is a cruise control switch...it disables the cruise

 

<br />
<br />
The switch is spring loaded. The spring inside the switch is what goes bad. Remember I told you the test? Remove both wires from switch and ground them together. Do lights stay on? If so your switch is bad. The switch controls the brake lights...you probably have bad circuit boards on the brake assemblies themselves if your switch is good and if you are wiggling bulb holders and then they light up. Remove the main plug from the back of the assembly and inspect the circuit board paper...this is normally where they go bad if they are....you can also test switch with a test light. Easiest with 2 people but you can also use a piece of wood etc. to hold brake pedal down then go back to lights and test for power...if test lights glows then you know brake switch is good and most likely circuit board paper....good luck.

 

Just posting this in case someone else has same issue. It was the brake switch. What was frustrating is I had mistaken the cruise control switch for the brake switch. On this 87 the brake switch is way up the brake arm. Touched the two wires together and bam...brake lights. $3.50 part at local salvage yard. Thanks again for the help.