Isue with the lights on rear of my truck

how about the parking lights in front ? are they staying on too ? sounds like possably the brake switch might need adjusted or your switch to the headlights is faulty

Check for a blown fuse.

Sounds like a faulty signal switch.Here's a way to check it,hold the brake pedal down while pushing down on and wiggling the hazard switch.If the brake lights come then replace the signal switch.

Hope this helps your out. I know the diagram and locator is a bit blurry but hopefully it gets what you need.
Drivers kick panel:
Front wiper 20A - Front wiper system Cigar 15A- Cigarette lighter Audio 10A- Audio, remote control mirror Air Bag 10A -Air bag diagnostics Stop lights- 15A -Rear brake light, high mounted stop light ECU B+ 10A - Shift lock actuator, transaxle controle module, radio, engine control module Room 10A - Interior light, clock, ignition key reminder, rear cargo area light switch ABS 10A- Anti lock brake system control unit ECU IG1 10A - Transaxle control module, shift lock actuator, ABS control unit, DRL unit Meter 10A - Instrument panel, back-up switch, electronics time control module, inhibit switch Turn signal 10A- Hazard switch ,front and rear turn lights, turn indicator IGN1 20A - Ignition switch ABS 30A- ABS pump motor TNS 30A- Tail light, license plate light COOL/FAN 30A- Cooling fan Cond/Fan 20A- A/C condenser fan Starter 15A- Start signal , Fuel pump Blower 25A- Blower Motor SR/ACC 10A - Ignition switch Hazard 15A - Hazard and turn signal light D/Lock 25A- Door locks ABS 30A - Anti lock brake system control P/W RH 20A- Power window motor right hand P/W LH 20A- Power window motor left hand IGN2 25A- Ignition Switch
Engine compartment :
Head 25A- headlights IG 2 30A- Ignition switch IG coil 15A -Ignition coil, condenser,generator IC regulator, diagnostic connector. O2 down 10A- Rear O2 sensor O2 up 10A- Front O2 sensor Fuel pump 10A -Fuel pump unit Injector 10A -Fuel injector ,camshaft positioning sensor, purge solenoid valve, EVAP, IAC actuator, Mass Airflow sensor, EGR stepper motor. fuel pump relay coil, vehicle speed sensor. A/Con 10A - A/C compressor controls, cooling fan BTN 30A- Brake light , high mounted stop light. Tail light LH 10A- License plate light, tail light , rear combo light, instrument panel illumination Tail light RH 10A-License plate light, tail light , rear combo light, instrument panel illumination Head low 15A- Headlight Head Hi 15A-Headlight Horn 15A- Horn

Inside kick panel

I've worked on these the first drove me crazy. its the turn signal switch every thing runs thru these. head lights, turn signal, brakes. except the third brake light. it runs directly from the brake switch. go figuare

check plug in rear what year truck?

yes, there is some posible isues
1. wire isues
2. switch isues

Look where the wires go to the lights underneath. Grab the white rubber piece that goes into the light housing and twist 1/4 turn. Then pull. The bulb just pushes into its terminal in the white rubber.

As cadman mention to check the fuse, and if there ok check your brake light switch along the brake peddle arm. Before you doany of that, turn your hazard light on to make sure that all your light's are not burnt out. Good luck

The taillamp bulb and the brake lamp bulb are the same bulb. The brake part of the bulb has its own filament, as does the taillamp side. The brake filament is brighter than the tail-lamp filament.
What you have is "1/2" of the bulb is burned out.
Go out and buy a # 1157 bulb, and replace the right rear bulb. This will fix your issue.
Glad to help, and thanks for choosing FixYa.