Low beams don't work. I replaced the high/low beam relay with a new one. Didn't help. Then replaced general headlight relay. Still doesn't work. Checked fuses. All good. Both bulbs look ok. Grounds secure. What is left?

 

only thing I think is left is the wiring to/from the lights and the light switch.

 

When did this start? What type of car and year is it?

If it's the type that has a permanent housing and reflector with a replaceable bulb, then the 9004 and 9007 bulb types can fit, but only one will work properly. Make sure you have the right bulb. I've seen it on a car my brother bought and one side acted like the low beam was burned out. Really it was a 9007 bulb in a 9004 lamp. The pin outs are a little different.

Since Volvo made cars with sealed beams, and replaceable bulb types through the 200, 700 and 900 series run, it's helpful to include what model and year of car you have.

 

and market. the occasional international poster here needs to identify themselves as we tend to assume they are talking about uS Market cars without any contrary clues. world market cars have completely different headlights, also alternate engines (B204GT, etc), wiring details, etc.

 

Sorry guys. I forgot you can't read my mind via cyberspace. Car is a 90 245. The low beams just stopped working suddenly. Both together. I've replaced fuse 15, the high-low relay, and the general headlight relay. I replaced the switch not too long ago on another issue, so am betting that isn't the problem. The filaments in both bulbs look good and since they stopped together, I find it hard to believe the problem is bulbs.
Am now waiting for a warm day so I can dig a little deeper. Any other ideas appreciated.

 

the 'step' relay aka high/low relay up front by the radiator, pin 56b is the low beam output, a grey wire, runs back to pin 6 on the bulb out sensor thats under the dashboard, then pin 7 (blue wire) goes to the right low beam, and pin 2 (blue wire) goes to the left low beam...

I think I'd get to the back of that high/low relay's connectors with a volt meter probe on that green wire on 56B, and check for voltage relative to ground when you think the headlights should be switched on.

 

Thanks. I'll give it a try.

 

Yeah I agree. You can always get some alligator clip wire and test them just to be sure, but it sounds like you have it right. Also you can double check with a multimeter on the socket contacts.

Since they quit at the same time it almost positively up stream somewhere where both lights are connected like what Pierce was saying. Checking that output there will help you know to trace back more or towards the lights.

 

yup. first principle of electrical troubleshooting. divide and conquer. Cut the potential problem space in half. then cut it in half again, until you reduce it to the root cause.

 

Good advice, all. I'll let you know the outcome.

 

So here's an update that adds to my confusion. High/low beam relay is working. Gray wire is low beam; red and some other wire high. Power through both at appropriate times. Tracing, I find current to fuse no. 7, but not beyond. Fuse is Ok. The big surprise is that my brake lights are not working. I had been so focused on fixing the low beams that I didn't notice this. So far, everything points to the brake light switch, but I can't, for the life of me, figure out what it would have to do with the low beams.

Of course, they put the brake light switch in a very difficult place to access, so I'm putting off working on it. Manana maybe. In the meantime, has anyone run into this situation? What am I missing?

 

the only common link between brake lights and low beams is the bulb-out sensor.

this is a beer-can shaped thing jammed up near the steering column on a 240, typically red or yellow (but there are other colors). inside it, there's a reed relay (glass tube that has two magnetized contacts... if you put a magnetic field around it, they stick together, closing the circuit that lights the bulb-out idiot light), and this relay is surrounded by a pile of coils that are counter-wound so they cancel in pairs if the current is equal.

the low beam 'grey' wire from the step relay goes into this sensor on pin 6, is split inside, and goes through a pair of those coils, and comes out on pins 7 (right, blue) and pins 2 (left, blue).

the brake light goes in on pin 9 (blue-red), and comes out on pin 5 (blue-black) for the high level brake light, pin 11 (yellow, right brake light), and pin 10 (yellow-grey, left brake light). the brake light has THREE coils that are counterwound to balance each other such that if any one is out the circuit is unbalanced.

if I was faced with a failed sensor that was killing my lights, I do believe I'd replace it with a mass of jumpers, by hacking it open, gutting it, and wiring jumper wires across its pins like...

(2-6-7)
(9-10-11-5)
(15-13)
(14-12)

[I'm getting this from the 1990 240 US version wiring diagram. other years and models and countries likely differ in various ways)

 

I like the part about gutting it. Maybe I'll shoot it first.

 

A little more sleuthing. We're on the right track. 1. Bulb failure light works with key on and engine off. 2. Bulb failure light does not come on when I apply brakes, even though brake lights and low beams don't work. 3. Bulb failure switch/relay shows two pins that have been very hot. Numbered clockwise, these are nos. 11 and 12. Labeled 56br and 56b. The pigtail contacts for these pins are melted. I've ordered a switch/relay and pigtail. Mystery now is why the pins fried in the first place. I'd like to check for a short, but not sure how to interpret my findings, if I do.

 

Replacing the bulb sensor and its pigtail solved the low beam problem. However the brake lights still don't work. Turns out the brake light switch isn't working (I bypassed it, and the lights work). So now I'll have to dig down into that mess behind the instrument panel until I've removed enough stuff to allow me to reach the brake light switch. I can't imagine why it was put in such an inaccessible place. Its a part you almost always have to readjust, if not replace. Oh well, as I tell my spouse, having to fix the car gives me an excuse to avoid yard work.

 

The brake light switch is easy to see and get to. Remove the lower dash pad where the pedal and lower vent is. Then you will be able to see it right on the brake pedal assembly.
You don't have to touch any of the upper dash stuff or instrument cluster.

 

To summarize, because I've replied before: the low beam problem was a result of a failed pigtail for the failed bulb sensor. I replaced the failed bulb sensor and the pigtail (after also replacing the two headlight-related relays). Low beams now work. However, in the midst of this, I discovered that brake lights were out. This traced to a bad brake light switch, which on the 90 240 is located in a position that should have resulted in the firing squad for the engineers that designed the car. I got it out after incorporating a long piece of wood that fit between the contacts on the switch, after managing to squeeze a 17 mm wrench up into the critter far enough to get a quarter turn and loosen it. This after taking two screws out of the cruise control "brain" to allow me to move it aside. A pain! Putting it back wasn't much better. After checking the brake light switch and confirming it was caput, I bought another. Sierra Auto. Truth or Consequences NM. Frequently heroes of mine. To put it back in, I used the same piece of wood that fit between the contacts on the switch, taped this time, and a pair of pliers holding the nut for the switch via a batch of rubber bands around the handles of the pliers with the nut holding the switch in place. Took an hour of fiddling and a glass of wine to get the threads started. So now, I'll put it together. Let us hope that the original problem didn't start with a short or some such thing I have not already located. This is our 9th 240. My wife loves them. I am her mechanical slave. Happy New Year