Originally Posted by
Jon S.
Sounds like things are not wired correctly. With a DBW P59 PCM, the TAC Module receives only one brake input (Cruise Control Brake Switch) - while the earlier DBC Cruise Modules received two brake inputs.
The switch on the OEM brake pedal has two inverse functions.
The PCM needs 12 volts when the brakes are not applied (for TCC lockup). This 12 volts to the PCM is then interrupted when the brakes are applied - which unlocks the TCC.
The TAC Module needs 12 volts when the brakes are applied (for Cruise Control disengagement).
Guessing that things have been wired such that the PCM and the TAC Module are both getting 12 volts when the brakes are not applied.