You really need an EVTM manual to trace down the wiring. Typically if the clock spring breaks (in the steering column) you lose the horn, OD on/off and cruise. Going with that mindset let's assume the signals are getting to the cruise control module located on the driver's side fenderwell. Your truck uses an electro-mechanical servo not the vacuum type as you correctly alluded to. Easiest quick check is to open the servo box, see if there is any water in it. This vintage of truck is well known to use that servo module as a rain collector.
If the cruise control modification has been installed I thought it was a fused link, have you checked the fuse? If it is open the servo may think the brake is on. Pin 9 on the servo is supposed to be the brake signal.
My last '93 Lightning had a bad servo, I traced the signals going into it, they were good. I swapped in a known good servo from my wrecked L' I had in the side yard. If you had an EVTM it would tell which wires to check going into the servo box.
I do not have an EVTM for a '95, but my '94 shows the signal from the steering column go into the servo amp on wire 151 (Light Blue/Black pin 5). Measure between that pin and ground. Pushing the Off button should measure less than 1 ohm. Set/Accel should measure 646 to 714 ohms. Coast should measure 114 to 126 ohms. Resume should measure 2090 to 2310 ohms. Make sure the Cruise fuse isn't open (Fuse 6?).
If the signals going in are good, it's a bad servo amp.
If the cruise control modification has been installed I thought it was a fused link, have you checked the fuse? If it is open the servo may think the brake is on. Pin 9 on the servo is supposed to be the brake signal.
My last '93 Lightning had a bad servo, I traced the signals going into it, they were good. I swapped in a known good servo from my wrecked L' I had in the side yard. If you had an EVTM it would tell which wires to check going into the servo box.
I do not have an EVTM for a '95, but my '94 shows the signal from the steering column go into the servo amp on wire 151 (Light Blue/Black pin 5). Measure between that pin and ground. Pushing the Off button should measure less than 1 ohm. Set/Accel should measure 646 to 714 ohms. Coast should measure 114 to 126 ohms. Resume should measure 2090 to 2310 ohms. Make sure the Cruise fuse isn't open (Fuse 6?).
If the signals going in are good, it's a bad servo amp.