Brake light switch

is the driver left side as in USA? (LHD or RHD)?
educated means too we read the service manual (SM)
and the page on rear lamps. Schematics, or we just fiddle about and guess.
https://eautorepair.net/Marketing/Default.asp


fuses all good, we check them all.
the problem #1 is on BCM cars, no 2 BCM work the same
so again the SM comes to our rescue.
BCM is body brain and runs all lamp, in odd ways, you don't know yet.
answering for only USA cars, LHD.
brake lamps are rear amps 2 or 3 total

that socket burnup (where) is signs of dead shorted lamp.
needs new lamp first and new socket 2nd.
the IPS runs all 3 rear stop lamps left, center and right.
facts, Schematic on my screen
all 3 lamps use the same single wire to glow. branks
but not ground
left uses GF04 ground wire to body.
GF04 ground runs the other 2 lamps.
so the only failure here is left lamp

• the lamp bad
• the wire bad (or socket0
• or the ground bad GF04

2 man job, step brake, 2nd man meter in hand.
a voltmeter tells you which one is bad.
step on brake pedal 12vdc here, all 3 on that 1 wire.
ground reads 0v.
yes ,yes, then lamp is bad.


meter black test wire must be to perfect metal ground for tests.
max ground volts is 0.5vdc max.but 0 is goal.
the lamp shorted I guess and burned up parts related.

Your rear left side combo lost a ground on the part of brake/signal lamps. Just put one more wire between parts.

Here is something that might be related to your issue, carefully inspect fuse box under dash, driver side. See if it is wet/moist with oily liquid on fuse side and wire side behind. If it is, its brake fluid from the brake master pressure switch that has failed causing brake fluid to be pushed thru the wiring all the way to the fuse box , shorting out the electrical system. The repair would require replacing the brake master pressure switch with an updated pigtail (supplied with new switch), and replacing the complete fuse box assembly, and I would recommend cutting and splicing new wiring from the brake pressure switch to the fuse box.

Have you done any checking using a volt meter?
Did you check the ground side of whatever you were
doing?
Need wiring diagrams before you get much farther

Sounds like you may need to replace brake bulb terminals they do get wore out were the bulb goes in easy to replace so new terminals easy to splice with wire splice kits don't twist and tape do this with splice kits or you will be always repairing take time do it right

No, it is not the brake lamp switch. If the brake lamp switch was not working, the high mount (3rd) brake lamp would also not function.
Chevrolet trucks are notorious for bad tail lamp circuit boards.

Disconnect the electrical connector from the circuit boards. Check for power at the circuit board connector (with the brake pedal depressed) on each side. The brake/turn lamp circuit for the left side is the YELLOW wire. The brake/turn lamp circuit for the right side is the GREEN wire. If there is power at the connector, check the GROUND (BLACK wires) to make sure they are getting a good ground. If the power and ground circuits are OK at the connector, replace the circuit boards.

NOTE: DORMAN makes a kit that includes circuit boards for both sides it is DORMAN Part Number 70001

If there is no power on the YELLOW and GREEN wires at the circuit board connectors, the most likely cause would be a defective turn signal switch.

This might work for you guy's replace the brake light switch
Easy step by step tutorial watch the video. im sure it will help.
MERCURY MARQUIS STUCK IN PARK
http://youtu.be/fgUn1TuHu-0

Hi and welcome to FixYa, I am Kelly

First check to see that your brake lights are working. The shift solenoid is powered by the brake light switch at the top of the brake pedal. If the lights are not working the break pedal switch can be bad. Listen for a click from the pedal switch as you just apply the brakes. No click = bad switch. IF the switch works but you still do not have lights check the Hazard fuse on the left side of the car just above the drivers side internal kick panel. If all of that is good the solenoid in the shifter assembly had failed. All of these repairs can easily be done by the average mechanic.

Thanks for choosing FixYa, Kelly

Alternator no but the brakes yes. Did you take it to a repair shop or do it yourself? Most repair shops have the programmer to reset the brakes on the odometer.

More likely it is the hazard/turnsignal/highbeam/cruise control switch module. It costs about $275 for the module. However there is a repair kit for the likely culprit...the hazard button. Try jiggling it around a little, see if that helps. Spray a little WD-40 into it so it can jostle back into it's correct position. You could try a junkyard unit or Ebay. It's not too hard to change. The hard part is doing it without removing the steering wheel. It can be done. I've done it. But hopefully you can locate the repair kit which costs about 15 dollars. Good luck.