I'd check the functions of the switch first.
Maybe the momentary up switch isn't working and activating the shut off instead.
Resume/Accel. is the yellow wire out of the stalk and steering column and the gray with black stripe on terminal M of the cruise control module.
Should have +12 on it when you tap up the speed momentarily.
If you do an OHMS check unplug the stalk flat connector from the socket next to the steering column and test between the yellow and blue wires for continuity when you hit the accel. button.