Angelo, you may not have the "crossover" connections under the cab connected properly, or some other connections are incorrect, the brake lights should only be able to work by going via the signal assembly, see the factory diagram here

Bill


Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics