Brake Lights, Rear Turn Signals, and blinker singal not working

Turn Signal Lamps
The body control module (BCM) is responsible for controlling the turn signals and hazard lamps. When the turn signal switch is placed in either the left turn or right turn position, the BCM receives a signal from the turn signal switch. The BCM then sends an on-off voltage signal to either the left or right turn signals and their instrument panel cluster (IPC) indicator. When the hazard switch is pressed, the BCM receives a signal from the hazard switch. The BCM then will send an on-off voltage signal to all the turn signal lamps. All the turn signal lamps will flash including both IPC turn signal indicators.
Stop Lamps
The body control module (BCM) is responsible for controlling the stop lamps. When the driver presses the brake pedal, the BCM will receive a signal from the brake pedal position sensor. The BCM then supplies battery positive voltage to both left and right stop lamp assemblies and to the center high mounted stop lamp (CHMSL). The stop lamps are grounded at G401 and G403. The CHMSL is grounded at G302.

Something is messing with the BCM'S mind ,bad input data ,shorted circuit etc... Hooking up a professional type scan tool is needed to read BCM DTC'S - diagnostic trouble codes an view live data to the BCM .

DTC B3948 02: Left Front Turn Signal Circuit Short to Ground
DTC B3948 05: Left Front Turn Signal Circuit Short to Battery or Open
DTC B3949 02: Right Front Turn Signal Circuit Short to Ground
DTC B3949 05: Right Front Turn Signal Circuit Short to Battery or Open

DTC B3950 02: Left Rear Turn Signal Circuit Short to Ground
DTC B3950 05: Left Rear Turn Signal Circuit Short to Battery or Open
DTC B3951 02: Right Rear Turn Signal Circuit Short to Ground
DTC B3951 05: Right Rear Turn Signal Circuit Short to Battery or Open

Your best bet ,take it to a qualified repair shop.

In the diagram for rear lamp, the top wires are voltage, the bottom black wire is ground. The brown wire on either side should be tail lamps, goes hot when you turn on the headlamp switch. The other top wire on either should be for turn signal. With everything turned on, is there voltage on that wire?
Because the front works and the rear don't, possible wiring circuit problem? The voltage for turn signals comes from bcm. The bcm knows when you turn on turn signal switch, either side, then the bcm sends voltage to turn signal lamp at the rear and front.

Brake lights /rear hazard lights not working - Ford Truck ...

www.ford-trucks.com > ... > 1967 - 1972 F-100 & Larger F-Series Trucks
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it all points to a fault with a common ground. Find earthing points

lol sounds like my old truck most likely crossed wires

I'm inclined to believe it is the turn signal switch. When you select left or right, the brake light is removed from that side, and the flasher is connected to the bulb instead, making the brake light on that side flash as the indication that you plan to turn. You have lost everything, but the simple answers check out.

If you have lost signals, brake lights and tail lights, then it is more likely that the ground supplied to the bulbs is not working, since the tail lights share noting in common with the brakes lights and turn signals but ground.

If the tail lights work, the fact that the brake lights and rear turn signals share that switch starts to look meaningful — even more so if the front turn signals also don't work. But the front signals and the rear signals use different circuitry in the switch, so it would be something more mechanical in the switch than electrical in that case.

I had this problem, and to be honest, it happened to the left side about a week later...it's the board that the bulbs plug into...it's a very common problem with this model. So popular that you can normally get the socket board off the shelf at a parts store! it's extremely simple to replace, and I replaced all the bulbs at the same time!

It may be a turn hazard module under dash.that is the culprit! The power to the third brake light does not go through the module, but the rear brake lamps power is controlled through this module. I am looking at a drawing of one and it looks like it has two connectors with about five wires in one and six in the other. It has some cooling fins on it also.

TURN SIGNALS WILL FEED BACK THROUGH THE TURN SIGNAL SWITCH.THEY ARE INDEPENDENT OUT SIDE ON THE CAR BUT NOT IN THE SIGNAL SWITCH.REPLACE THE SIGNAL SWITCH

I have a 2002 Chev Cavalier that had the same exact problem. I replaced the bulb harness (purchased from a chevy dealership for around $5) which was fairly easy to do. I have had zero problems with it since.