Its time for that stupid annual PA Inspection (even thought its registered as a "classic" car).

The light bulb thing kept popping up on the dash when braking.

Parking lights - check
Reverse lights - check
Turn signals - one was out, a little wiggle wiggle and dielectric grease - check
Brake lights - no worky worky (all 3)

Bulbs check out fine, sockets seem tight, little dab of grease on connections (worked before) and still nothing.

Checked fuse #7 - check

Thoughts?

 

the switch itself?

do the tail lights work when lights are on?

 

um, what model and year car is this? if I've got the wiring diagrams, I can track down wire color and such so you can do some volt meter tests...

 

Pierce, 1993 240 Wagon

The switch works, tail lights on when lights are on, just no brake lights

 

well, the wiring diagram is /really/ simple.

fuse 7 should be always powered (even with the engine off). it has a green-red wire to the brake light switch (on the brake pedal assembly under the dash), from that switch its a blue-red wire to pin 9 of the bulb-out-detector beercan thing up under the driver side dash.

pin 5 of the bulb-out can goes to the high level brake light via a brown-black wire (which goes down the harness in the driver side door sill, up over the rear wheel up, then up the left side D pillar, and out the left side door hinge).

pin 10 of the beercan is a yellow-grey wire, this goes to the left side brake light.
pin 11 of the beercan is a yellow wire, to the right side brake light.

all three of these go through a 'connector F' somewhere behind the fuse panel, shown as a 24 pin 2-row connector.

note there are early and late 1993 240's, the 'late' ones have an additional fuse box with 4 power fuses near the battery, this circuit is on fuse "Y" on those cars (but so is the ignition switch and a pile of other stuff)

 

check the "bulb failure" relay, the big round red one--first thing i look at if all 3 brk lites are inop

 

yeah, thats the 'beercan' I refer to

on a 240, I believe its behind the dashboard, near the steering column. i'd try and stick a volt meter probe into the back of the socket on pin 9 (blue-red wire) with the other probe on a handy chassis ground, and depress teh brake pedal, see if you get volts there.

if you DONT, the problem is upstream at the brake switch.

if you DO have volts there, then stick the probe on beer can pins 5, 10, and 11, and see if you have volts there. if not, then the bulb-out detector is bad.

if I had a bad bulb out detector, I dunno but I'd probably cut it open, gut it and replace it with jumper wires. pins 9-5-10-11 should all be directly connected. pins 3-6-7 should be connected (thats the lowbeam circuit). 12-14 (right parking lights), pins 13-15 (left parking lights), should also be connected (but not together)

 

Ok, royally confused on all the wires and such, never been so good at electrical, except wiring houses.

I'm going out tomorrow and taking the cover so I can get behind the steering column, trying to look under it in the driveway at twilight wasn't really helpful and at 15 degrees not fun. It's a balmy 33 tomorrow so that'll be nice.

Where is the "beer can"? When I looked up under there I didn't see any thing that looked circular, saw a bunch o the white squarish connectors and a relay of some sort (looked similar to the fuel relay).

And what do I do for volt meter testing? Sorry just a noob when it comes to the electrical, swapped the head with no problem but can't figure out brake lights lol

 

its really more like the size of a frozen OJ can, not quite a beer can. I don't have a 240 handy anymore to look at (my daughter's moved ours to Portland, OR), but I believe its somewhere above or near the steering column, maybe on the firewall. on a 740/940, its plugged into the left slot of front-most row of the main fuse/relay panel behind the ashtray...


ah, this diagram shows the 1993 240 has it more like below the far left dashboard air vent.
http://www.davebarton.com/pdf/relay_93_240.pdf

see partway down this page for some more of this beast.
Volvo Relays
(there's 4 different versions, yours has the RED one)

and also here for the general idea on bypassing, except the diagram is only for the YELLOW one used on 1978-1985 240s.
volvo240
so if you DO decide to try and hack yours like he describes, note the wire numbers I posted above

as far as explaining volt meters, ugh. know anyone handy with electronics?

 

Found the beer can, if I put the voltage meter lead into pin 9 how much voltage should there be?

The only thing with the beer can that looked suspect is that it looked a little deformed right around the grey wire. Not melted or burnt just deformed.


I didn't see a green/red wire to the brake light switch, the only thing I can see on the brake pedal assembly is a white connector with two wires, one blue and one white connected to a plunger looking thing that's pushed in when no brake applied, plunger out when brake applied.

Now the 3rd brake light is working, but the two below are NOT working, everything else works.

 

extra fun on a 1993, there's an 'early' and 'late' version of the wiring diagram. Sven only knows why they changed things rather drastically midway through the last year of production. these 'late' 1993 cars have another fuse block under the hood on the battery plus connector with 4 big fuses, instead of the 'positive terminal' all prev models used.

lets see, on both versions, there is an all grey wire for power for the right tail light (pin 14 of the bulb-out can), and another for power from the light switch for the lowbeams (pin 6). that blue wire next to it is probably low beam right (pin 7) so I'm guessing the melted grey connector is pin 6. the brown/black wire on pin 5 is the 3rd brakelight.

you should see 12V.5 or so on that pin 9 when the brake pedal is depressed with the engine not running, pretty much full battery juice, minus maybe a 1/10th volt for the drop from wiring and connectors. with the engine running, its probably a volt higher.

so, if you see juice (12V) on pin 9 when you step on the brake light, you should ALSO see juice on pins 5, 10, and 11. 5 is the 3rd brake, 10 is the left, 11 is the right. if you DO see juice on 10 and 11, its time to check the back, find the yellow (right) and yellow-grey (left) wires at the tail lights, and check the voltages there relative to ground when the brake pedal is depressed (helper required, or a handy 2x4 or something to wedge the brake pedal down...)

if you see power on the yellow and yellow-grey wires and there's no brake lights, then the problem is IN the light assembly, something isn't making a good connection, maybe the socket, or maybe the crappy mylar circuit film.

 

Almost success.....almost.

Voltage on the beer can check out everywhere, so we're good there.

Went to assemblies and wires in the back.

(note: when in for state inspection I had a cracked brake light cover, just the cover, they wouldn't pass it, so I had to get new assembly, they wanted $250 from the dealer for one, I got one from FCP for $63, anyway).

Driver side, bottom light was on, when brake light pressed, light got brighter. Checked wiring, they had the brake light wire on the bottom, switched it up, brake light works and the bulb indicator dash light goes out, yeah.

But.

Passenger side, bottom tail light on, same thing, brake pressed tail light gets brighter. So I figure the same thing, well, they had a white and something wire (it was getting dark) going to the brake light, obviously wrong. But the yellow wire that should go there is too short to reach.

So, indicator light off, passenger tail light is hooked in with brake light, hmmmm.

how to get that yellow wire to the top?

 

this is a 240 wagon? my drawing shows the brake light on the bottom position.

it shows the yellow or yellow-grey wire to the bottom, black wire between the middle 2 bulbs.

the parking light is a brown-white (right) or red (left) wire which also goes to the bottom socket (probably a different spade, as the drawing isn't that clear), its a 2-filament bulb.

the turn signals are the 2nd bulb from the bottom, and the wire is blue or blue-green, right next to this socket.

the 2nd bulb from the top is the reverse light, and has a red-black wire that goes to the spade right next to this socket (2 red-black wires on the left side, as one goes over to the right).

the topmost bulb is the 'rear fog lamp', and is a violet wire on top. only the left side is wired and functional.

oh, and the dual filament parking / brake light in the bottom position, the brake light should be a lot brighter than the parking light. if they aren't, swap the yellow wires for the brown-white or red wires.

 

hmmm did not know the brake lights were at the bottom, never thought about it.

Will switch them back tomorrow and see if the bulb failure light comes on, when I switched the driver side is when it went out.

will keep you posted