My check engine light keeps coming on. Its throwing 3 DTC codes . Code 41 brake switch test fail... code 42 fuel temp high (low voltage). Code 87 high tatio.. if ne one know what r y and how to fix theses codes let me know. Its a 94 chevy 1/2 ton 4*4 180k miles. It runs good just got tranny flushed ..well i hope to get some help here. Merry christmas ... happy new year

 

i would like to think you have bad grounds somewhere if your getting low voltage. and i would replace the brake switch

 

try clearing the codes see if they don't come bad

also check and clean grounds

now these are know for brake switch go bad