Pump Mounted Driver.... An electronic box that controls fuel delivery on the 6.5 Turbo Diesel.
Thinking there may be a similar ancillary device on the 6.2 that might not be a "usual" cruise control component that is normally suspect....
I'm not very familiar with the 6.2s.
The guys over at diesel place forum will be much more knowledgeable about 6.2s.
His 6.2 is mechanical injection so it won't have a PMD.. but you're right, the diesel guys may be a lot more help. Hell, I don't even know what the cruise setup on a 6.2 is.. most likely it's electric motor/cable-operated like a gas truck. Those cruise modules themselves rarely go bad...but there is some troubleshooting that is likely going to be the same as a gas truck:
#1 suspect is the turn signal stalk as the wiring often breaks (internally) where it bends going into the column on the pre-1995 design. There's a plug underneath the dash roughly above your left knee, clipped to the dash sheemetal support, with an orange tab (usually) on it. You can unplug it there and use a meter set on continuity to probe the 4 fingers on the connector. One is ground, the other are the button/switch functions. Can't trace color to figure out which is which as the wires are all in a black jacket but it's not hard to figure out which is which and test the other 3 against the ground to see if the wiring is good.
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#2 suspect is brake switch, even if the brake lights are working. There are 3 sets of connections in there on leaf switches. Brake lights, cruise disable, torque converter clutch unlock. The leafs get weak over time and break inside the switch or just lose enough spring tension that they don't work correctly anymore. You can simply unplug the switch and check each set as you'll see there are 6 pins on there; 2 pins for each switch. The pre-1994 switch is adjustable and can get out of adjustment but if your brake lights are working it is likely adjusted correctly.
Richard
