GMC Troubleshooting Questions? Ask a Mechanic for Answers
where do you hear the clunk from ? what speed will it make this clunk noise ?
see if there are any codes set
if not what gear will it do this is ?
i didnt ask about 4WD i asked what speed it will do this
the 128 is a bad thermostat
the 16 is a big problem as that code says the carnk to cam timing is off
that can be caused by low or dirty engine oil or a loose timing chain or the rare chance of the cam actuator phaser
then see if it still does this
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if you clear the codes what code will reset ?
yes that is correct it is not supposed to be stuck open
first see if there any codes being set
does it feel like its slipping in and out of gear ?
at this point it needs to be driven with a scan tool monitoring live computer data and live transmission data and see what reading is not right when its acting up
just internal transmission failures of the 3-4 clutches
we did not have too many issues with the transfer cases on these trucks