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Eric, Automotive Repair Shop Manager
Category: Chevy
Satisfied Customers: 31893
Experience:  20+ yrs. experience as repair shop manager and technician.
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I am a former gm tech looking at a strange one. 2000 blazer

Customer Question

Hi I am a former gm tech looking at a strange one. 2000 blazer with np236 t case. 4 button auto. sets c0327 encoder fault only when the console shifter comes out of park. not pushing any 4x4 buttons. tech 2 shows all encoder readings go from normal to invalid if shifter is moved out of park but all read correctly as soon as you put shifter back in park. no corrosion at tccm plug, tried new tccm,encoder, pnp switch ohmed all 6 encoder circuits and all test good in or out of park. 8 volts and ground remain steady as well but abcp encoder readings all go high on scan data and shows invalid only when shifter out of park. t case will shift into 2 4 auto if left in park. 4lo will only blink due to you need to be in neutral but you cant or it will set code and lock out further tccm shifts. trans data shows correct position of pnp in all gears. Pcm has newest calibration and i verified vin is programmed correctly. only other issue noticed is with btsi interlock. brake lights work and key needs to be on to shift out of park but you do not need to step on brake to come out of park. related ?
Submitted: 1 year ago.
Category: Chevy
Expert:  Eric replied 1 year ago.


I have uploaded the testing procedure to start with, but if I could get the vin number, I can check for tsbs for this vehicle that may be related to this

Customer: replied 1 year ago.
Eric Thanks but I already have this checkout and schematics. It leads nowhere. I have access to SI . no tsbs for this concern. what circuit does the tccm use to know if the vehicle is in park or neutral? Or is it getting this info over communications line?