95 Volvo 850 Brake Light Problem

Thanks for any advice you can give me. All the brake lights (both sides and high mount) have stopped working. The fuse looks good and has been replaced as a precaution. Both bulbs have been
replaced. When I put a meter across the fuse connection, I see 12 volts when the brake pedal is depressed, which makes me think the switch is OK.
Where to look next?
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On Tue, 30 Jan 2007 17:14:02 -0600, "Mike G"

Well, Mike, if *none* of the lights are working and you've replaced the bulbs, I would suspect the switch. You say the fuse has been replaced so that should rule out that problem. I would be inclined to pull the switch and check it with an ohm meter.
Chuck Fiedler Nothing but Volvo since 1974 Currently a '93 240 and a '97 850
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Mike G wrote:

If you see voltage across the fuse, that's your problem. If you're seeing voltage between each side and ground, then the fuse is OK.
After checking the switch on the brake pedal, see if there's voltage (pedal depressed) at the bulb failure relay. It's located inside the left frame rail inside the trunk. Look for power at the terminal marked "54" which is the input for all brake lights.
--
Mike F.
Thornhill (near Toronto), Ont.
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with the fuse inserted or without fuse?
If the fuse 11/12 is in, the pedal depressed and you can measure 12V, the fuse is broken. Then after releasing the brake pedal you should not be able to measure any voltage across the fuse except when having a ground shortcut somewhere on the way between fuse and brake switch.
If the fuse is in and ok the voltage drop is practically zero and you should never be able to measure a voltage across the fuse connections.
If the fuse is out the behaviour should be as with a broken fuse in.
Not being an expert, but after studying the wiring diagram for the five door 850, in case you do not have access to the circuit diagram, maybe the circuit layout is useful for you to solve the problem.
The circuit is: battery plus - fuse 11/12 - braking switch 3/9 - branching point 23/201 - connector 24/14 - in at connector 12 at bulb malfunction indicator 7/1 - 3 lines (10,13,14) out from that to the rear left, rear right and high mount lights, each of them then to ground. Since all 3 lights dont work and if the fuse is ok, the brake switch is declared not guilty, the problem should be after the brake switch and most distant within the bulb malfunction indicator.
In my drawings the components are located in the 850 five door: connector 24/14 left of the steering wheel (under the dashboard?) 7/1 bulb malfunction indicator somewhere left in the trunk (under the floor near left back corner?)
in the sedan the 7/1 should be somewhere near the left rear light.
The brake light switch seems to be a simple mechanical switch somewhere near the brake pedal.
To be taken with a grain of salt since I myself have not had to work on the braking light circuit of my 850 yet.
Regards
--
Viktor Weisshupl
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