Brake Lights not working when brake pedal depressed. The rear brake lights work with the head lights on, but do not work when you depress the pedal. So the lamp is good, but the intermediate wiring is not. The cab light works with the brakes, but not the two rear lights.

check the bulbs then check power to the bulb contacts .as it can be a break in the wire were the trunk/boot opens up.

The flasher does not stop the brake lights from working. Check # 18 fuse in fusebox under lower left side of dash. if it's ok, the brake light switch, on the brake pedal arm is next. light green wire with red stripe is hot if fuse 18 is ok. Depress brake pedal, light green with no stripe should have power. if not, replace brake light switch. If light green wire has power with pedal depressed, combination switch under the steering is next. Remove the cover from around the combo switch {under the steering wheel}. depress brake pedal, light green wire should have power. If it does, pedal still depressed, orange with light blue wire & wire with light green & orange should have power. Those 2 wires are brake & rear turn signal wires. { The turn signal switch should be in the middle, not right position or left. while checking for power in the last 2 wires. Good Luck drvolt.

Hi,
check the brake light switch located in the brake pedal area. Normal procedure is to remove the two wires and connect a jumper' wire between them, check and see if the rear brake lights operate. Check the brake light switch and see if it is adjustable. If so, re-connect the removed wires, adjust the position of the switch untill the brake lights operate,when the brake pedal is depressed, then secure the brake light switch.

there is a switch above the brake pedal that turns the brake lights on when u depress the pedal, use a volt meter set to DC volts and check for voltage to the switch and out of it when the brake pedal is depressed, see p[icture of switch below

It is most likely the alternator.

i just recently replaced my brake lights and running lights

are you sure you wired everything correctly?
check again especially your grounds

Something is being missed,start with checking the fuse for the brake lights. Then check the brake light switch for power in and out(when depressed).Your ground is intact so no power. If still nothing, remove the lamp in question and test the contacts. good luck. Don't forget to depress brake pedal while probing contacts.

check pedal switch

no disrespect but....
Check the book and make sure you are using the proper bulbs on all sides. (3957 looks just like 3956 but wont work right)

Found a bad earth connection.