Been reading through the old threads to diagnose a brake lights out situation. All 3 lights are out. The bulbs and fuses are good and clean. Same with ground points of tailights. I used a multimeter to test continuity at the brake light switch at the pedal and hear the beep when the pedal is pressed. I swapped in a known good BFSRelay from my other 240 and still no brake lights. Is there a harness connector somewhere that may have come loose? Any other thoughts?

How do you know the fuse is good and clean?





http://cleanflametrap.com/brakelights.htm
--
Art Benstein near Baltimore

Marathon runners with bad footwear suffer the agony of defeat.

A good lesson to learn is:

1) Always listen to Art; and,
2) Start with the small stuff.


So my reputation for being an idiot is apparently well-founded. After Art's post I went to confirm that the fuse was indeed "good". And what did I find? What didn't I find more like it. There was no fuse! In my haste I didn't pay close enough attention to what fuse I was looking at (and rotating, and cleaning, etc.) when checking the "stop lights" fuse. On my car there is a blank fuse slot next to the brake light fuse and I must have not paid close attention the last time I did my last fuse cleaning interval which was a few months ago. I was probably driving around without brake lights since then totally unawares.

Put in a nice clean new fuse and brake lights came on immediately nice and bright.

Please learn from my foolishness (and Art's wisdom) and check the small things (closely) first.

It is always the little things that stop electricity when there are at most about 12 volts.

It was a bit of a learning experience for me to closely watch the element in the brake lamp fuse while using my right hand to activate the lights by pushing on the pedal. I see the element flexing as it heats and cools. That explained the tiny crack that eventually develops in the middle of the element.

If there's any general lesson here, it is in the electrical troubleshooting mantra I remember from far back: "First check the power supply." Easy to say, but sometimes it just feels better to take a poke at the "usual suspects." The BFWS is high on that list.
--
Art Benstein near Baltimore

A Local Area Network in Australia is the LAN down under.

With a multimeter, you should test for 12 volts at both sides of the brake switch, then at the rear of the car.

Do you have rear directionals that work? Do they have separate bulbs?

Some cars with single rear bulbs pass the brake light power through the directional switch.

Are all the bulb sockets in their three original positions?

Some people swap them around during troubleshooting - I did that in out '90 744 TI and nearly burned up the lenses!

Often, when I troubleshoot, I take a fused wire and run 12 volts directly to the device that does not work - then run tests back to the power source. Take a piece of wire plenty long enough and cut it about a foot from the end you want to connect to the battery. Add female spade connectors to the cut end and insert a spade fuse - you now have a fused wire. I carry several wires with different ends in my 544 for emergencies.

A single strand of one of the wires can trip a continuity test, and show voltage, but it cannot light a brake bulb.

This happened to a headlight on our '88 745 GLE - I stripped the wire back from the headlight and found a lot of black gunk about 1 foot from the bulb and only one copper strand. I had to replace the headlight wiring back to the firewall.

"A single strand of one of the wires can trip a continuity test, and show voltage, but it cannot light a brake bulb."

I had read something similar elsewhere which concerns me. If i'm getting a beep at with probes on either side of the switch when pedal is depressed, how can I be sure the switch isn't the fault? Is there a better way to test it?

Isn't the harness routed through the tailgate on the 245?
http://www.volvowiringdiagrams.com/?dir=volvo/240%20Wiring%20Diagrams/1975%20240%20Green%20Book%20Complete

No, the brake lights are not routed through the tailgate, but rather are routed from driverside to passenger side underneath the tailgate lip.

Lift up the hatch cover where the third might be, if you have one, and there is rubber conduit that hides the wires.