My daily driver is a turbocharged Ranger and I live in Colorado.  I like to ski and drive to the mountains sometimes weekly during the winter.  I run a 195/75R14 snow tire on all 4 corners in the winter, so I turn down the boost to 8psi to keep the tires from spinning the studs out.  8psi is great for tire conservation, but it sucks at highway speeds. 

The idea was to have low boost at speeds less than 35mph and full boost (18-20psi) at highway speeds.  Since the L series processor is equipped with two A4LD outputs (pin 42 and pin 53) and I am running a manual transmission, I decided to use the A4LD code and output to control a boost solenoid.  I am using a SAAB APC boost solenoid, but the Ford BCS can also be used.

I used at the 3rd/4th gear shift maps and other parameters to make this controller work. Since all outputs on the L series go to ground when activated, I hooked up pin 42 to a light in the dash with Key-On power applied to the other side of the bulb.

The played with the 3rd gear maps M_0920 and M_0951, but they had no effect on pin 42, so I set both of them to 0

I don't want the boost controller to stay locked once desired speed is hit, so I set M_0982 to 128

To get the pin 42 ground to release when throttle was removed, I had to set the M_09B3 map to 5mph less than target mph.

Map M_09E4 is the map that determines when pin 42 goes to ground.  With a part throttle acceleration, I am able to keep the boost setting low.  Go beyond 1/2 throttle and 35mph and pin 42 goes to ground.

Another map I had to tweak to get the pin 42 ground to release was M_0A15.

Parameters - Thanks to the help of dan_xr4 and svojohn I was able to keep my shift light function using pin 53 AND use pin 42 for the boost controller.  P_01F4 is set to 31 (31 hex)  and P_0400 is set to 4 (04 hex).

Wiring - I used the VPWR from the EGR solenoid to provide +12V power to the SAAB APC solenoid and pin 42 is connected to the ground side of the solenoid.