No, the TCU does not need vacuum. It has no vacuum ports on it. The vacuum dump valve is a double safety to make sure the cruise control servo loses vacuum when the pedal is depressed, along with the electrical signal to the cruise control's "brain" losing it's electrical signal. Liability and safety issues.
Running in Comfort mode, having a blown 7.5 amp trans fuse in the fusebox, (which has the same effect), Bad Power/Comfort switch, and bad TPS on the trans side are your most likely suspects. Steer away from the vacuum causing the issue and concentrate on the above mentioned possible culprits.
OMG, READ MY LIPS! LOL,
I said nothing about vacuum to the TCU or TC!!!!!
The vacuum is applied to the special brake switch,
brake switch number II, it is white, and it is not the standard brake light switch, but a separate switch used on jeeps that have or had Cruise control, that sends the signal to the TCU (electrical signal), telling the TCU if the brake peddle has been pushed. From your description above:
The vacuum dump valve is a double safety to make sure the cruise control servo loses vacuum when the pedal is depressed, along with the electrical signal to the cruise control's "brain" losing it's electrical signal.
So do you know exactly what the vacuum switch on the brake II switch is doing? How it interfaces with the Cruise control E-module (Yellow box under the dash) and cruise control Mechanical module under the hood that operates the throttle while in cruise mode. What about loss of vacuum to the cruise control Mechanical module under the hood that operates the throttle?All I know for sure is that they are all somehow interconnected!!As the TCU must unlock the TC for the brakes to be able to stop the jeep with out killing the engine, or hitting something in front of the jeep!
I am not saying the vacuum is his TC lock up problem, only that it sounds like he may have created more problems ripping all those vacuum lines out, including some how confusing the cruise control computer, and TCU!!!!!
It sounds like you were saying the white brake switch is an electrical switch and an air/vacuum valve, that only dumps vacuum to the cruise control while breaking, is that right?
Edit: Does it only talk to the cruise computer? Is it the second set of contacts on the brake switch I that feeds the TCU data for TC lock / unlock? I always thought the TCU signal for the TC lockup came from the white brake switch?