The third brake light is always on and the abs light also frontier 2002

A key question is whether the power brake assist is normal while driving. If it isn't, you may have to depress the brake pedal 'hard enough' to actuate the ABS system. Do you notice typical ABS modulation of the brakes while the pedal is 'hard'?

Personally I'd think any fault with the ABS itself would throw a code, either setting the ABS light on the dash or providing something in the OBD-II scan. Have you observed any codes resulting from, say, a free scan at AutoZone?

Hi Henry. I'm Tim Dorton. Did you pull a code out of the ABS? If not here is the manual.https://manuals.co/workshop/nissan/frontier-d40/nissan-frontier-d40-2006-frontier-model-d40-series-service-repair-manual/5874563

You could have two separate issues or just one. First check the level of brake fluid. (brake light)Fill it and if the light goes out, then you have to use a CReader or scanner to get the ABS codes. Cold be wheel sensors, broken wire, or the ABS module. If you can't get the brake light to go out, then it is the ABS, three possible causes. One is the ABS module is dead. second is the pump has failed. third is a bad ground wire. check the ground first. The ground is the biggest wire going from the pump /module to the body. When these loose ground, I cut the end off and run a longer wire to a better spot on the body. When you see it, you will know why.

check for a loom connection to the rear as it may have come apart.

should be two screws that would remove the cover. that would get you access the the bulb.

Some part's store are able to read ABS code ! \A wheel bearing going bad can cause false ABS activation .

It stands for Anti-lock braking system, and the reason the ABS warning light is on is due to a problem with the ABS system

Hello , does the ABS system function? You may have a faulty wheel speed sensor, or a faulty ABS control mod. Quinn ,Arizona

if you have rear abs then yes. you may have pinched the cabl attached to the wheel bearing

The ABS system always is engaged when the brakes are applied. If you are talking about the ABS light coming on then it is a little bit of a different story. If the light has come on at all there will always be a code stored. I would take it to a shop that has a scan tool to read ABS lights and ask them what the computer is saying. This is the only true way to get this problem fixed.