brake lights don't light

Check the bulb failure sensor.

Baffles me why anyone uses R-12 anymore, you can convert the system to R-134 including all new seals and rubber hoses for a couple hundred bucks, then it's only around $30 to charge it. AC is not difficult to work on, you need a few specialized tools but even those are not expensive.

the 740/940 wagons are great cars, what better can you get for the money?

This may be the culprit. I'm trying to find a brake light relay and this is as close to that as I can find, looking for relay diagrams...

The switch checks out fine but runs counterintuitive. That is, the switch is pushed in and on, supplying 12V when the brake pedal isn't touched. Pushing on the brake pedal releases the switch and cuts the juice. So, a 12V signal keeps the brake lights off. Remove the 12V signal and some gizmo should switch on the lights.

But, I don't see anything relating brake lights to a single relay. But the "bulb failure sensor" is right there on the realy panel (behind the fuses). Maybe the relay shorted out and fried when the taillight got crushed and filled with snow.

There's a headlight relay, but I doubt that's connected. Anyway, I can try those two just by parts swapping off the donor car, I think.

Well, including [parts that's not a ton cheaper unless you plan on multiple recharges. It's a done deal. And the people considered that option, but had seemingly good reasons to stick with the refrigerant of design. I knew beforehand that there are very significant differences of efficiency between the new and old stuff. The guy has been doing auto A/C for 50 years and will just talk your ear off. He says the condenser isn't right for R-134 and a hot day will really overwork the system and have pressures too high or some such thing.

He did some value extra checking my work with flourescent dye in the oil, and heated my dryer filter twide to reclaim the dessicant, and did his best to get the oil quantity right in the system (not easy without a full flush of the system which I didn't do.

I have been very happy with the many Volvos I have owned over the years. And I flog them hard too. The old rear drive cars are a pleasure to work on.

Thanks for your response, BTW.

-Dean rambling...

That sounds more like power to the cruise control.

"James Sweet"

Bingo. Ten points for you. Part number1362370

Must've shorted out I guess. Now I'm wondering how the circuit works, just to understand...

Thanks.

-Dean

I don't think there is a brake light relay. IIRC, +12V is supplied to the switch all the time, pressing the pedal causes the switch to close and turns on the lights in a 240, I'm surprised if the 700s are any different. The bulb failure sensor commonly suffers cracked solder joints, I've fixed a pile of them over the years.

You always plan multiple recharges, the stuff has leaked out afterall, it will leak out again eventually, and there's a good reason they don't make it anymore.

I've heard the efficiency arguments as well, but I converted mine years ago and it works great, cost me about $200 and I haven't touched in since. It's rarely above the mid 80s or low 90s out here, but I've never had any complaints about it. There is a slight difference in efficiency between R12 and R134, but "very significant" is an overstatement. I'm licensed to buy R12 but I always convert systems I work on, I don't like to put CFCs in automotive systems because they always leak eventually.

Pop the cap off and look at the circuit board, you'll probably find cracked solder joints in multiple places.

The older sensors are simple and clever. For each light circuit, there's a reed switch around which are two bifilar wound coils of wire. These coils are wired out of phase with each one in series with the lamp on one side. When current flows through the circuit and both lamps are working, the magnetic field is equal but opposite due to the out of phase wiring and cancels out. When one bulb is bad, the magnetic field causes the reed switch to close and the warning lamp on the dash illuminates. Of course if both lamps are burned out, the warning will not be on.

Well, the switch shows an open circuit with the plunger extended and continuity with the plunger depressed. The brake pedal's arm contacts the switch depressing the plunger and thus gives continuity when there is no foot on the pedal. When you push the pedal down the arm loses contact with the switch and opens the circuit.

The red cylindrical ones (about 47mm diameter and 5cm tall)? I opened the bad one up and it's a three tiered stack of circuit boards. Everything looks solidly connected and unburnt. But there's a faint smell like somebody let the smoke out of one of the componenents.

I found a wiring diagram here:

it seems to show both66 Brake Light Switch G3and

229 Brake Pedal Switch W2

so... the mystery thickens. But the car is ready and my daughter can take it back to college, so I'm on to the thing I really should have been doing all day.

Thanks again.

-Dean

Cool. This will be fun playing with this thing trying to find the bad spot. Visually it looks good. Smells like the smoke got out though.

some plums in a neighbor's lot, knowing nothing of any harm in what she did; but when she brought some of the plums into the house, her mother mildly reproved her, and told her that she must not get plums without leave, because it was sin: God had commanded her not to steal. The child seemed greatly surprised, and burst out in tears, and cried out, I won't have these plums! and turning to her sister Eunice, very earnestly said to her, Why did you ask me to go to that plum tree? I should not have gone, if you had not asked me. The other children did not seem to be much affected or concerned; but there was no pacifying Phebe. Her mother told her, she might go and ask leave, and then it would not be sin for her to eat them; and sent one of the children to that end; and, when she returned, her mother told her that the owner had given leave, now she might eat them, and it would not be stealing. This stilled her a little while; but presently she broke out again into an exceeding fit of crying. Her mother asked her, What made her cry again? Why she cried now, since they had asked leave? What it was that troubled her now? And asked her several times very earnestly, before she made any answer; but at last said, It was because, because it was sin. She continued a considerable time crying; and said she would not go again if Eunice asked her an hundred times; and she retained her aversion to that fruit for a considerable time, under the remembrance of her former sin.

She sometimes appears greatly affected, and delighted with texts of Scripture that come to her mind. Particularly about the beginning of November, that text came to her mind, Rev. 3:20, "Behold, I stand at the door, and knock: if any man hear my voice, and open the door, I will come in, and sup with him, and he with me."

are not, and the kingdom of God is within you.The Rabbis.

661. Penitence, alone of all these mysteries, has been manifestly declared to the Jews, and by Saint John, the Forerunner; and then the other mysteries; to indicate that in each man, as in the entire world, this order must be observed.

662. The carnal Jews understood neither the greatness nor the humiliation of the Messiah foretold in their prophecies. They misunderstood Him in His foretold greatness, as when He said that the Messiah should be lord of David, though his son, and that He was before Abraham, who had seen Him. They did not believe Him so great as to be eternal, and they likewise misunderstood Him in His humiliation and in His death. "The Messiah," said they, "abideth for ever, and this man says that he shall die." Therefore they believed Him neither mortal nor eternal; they only sought in Him for a carnal greatness.

663. Typical.--Nothing is so like charity as covetousness, and nothing is so opposed to it. Thus the Jews, full of possessions which flattered their covetousness, were very like Christians, and very contrary. And by this means they had the two qualities which it was nec