Jk is correct. I believe on the 5000 there are rotary type knobs to do certain functions i.e. shut down the CPU, Inspect or place the car on "Door Disconnect" (Test?), or maybe even taking the car out of the group. The feature you're looking for is Door Disconnect. Once this is active, the tool will say "Door Disconnect" where it would normally say, "Automatic". Run it all day long without the doors. I'd look at the selector guides for wear. Kid you not, I had an Futura job where 3/16ths" (total play) wear on the nylon guides would give me DPP errors because the selector tape had straight holes rather than elongated. If the 5000 selector has LEDs for DPP1 and 2, run the car on cartop inspection, watch the LEDs toggle on and off. Push the selector box back and forth to see if there is any miss in toggling of the LEDs. Another area of trouble is simply broken/loose wires at the termination points on those Spretcher Shue relays.
