Article by member 19PSI
so i really wanted to be able to use 2 low for backing my trailer and other uses.
well, i looked at the vac system and figured out a way to make it happen.
having built several turbo mitsubishi eclipses, i am very familiar with their systems and kjnew that the factory boost control solenoid could be used to control the vac to the front axle on our trucks.
i simply spliced the boost control solenoid ( not needed on a tuned eclipse turbo) into the vac line on the firewall. then i grounded one wire and supplied power through a switch inside the cab. no relay needed as it's a very low current device.
the mitsu solenoid is a normally closed valve, so applying voltage opens the vac ports and allows vacuum through to the front axle.
so normally, i'd leave the voltage off for normal driving. so i don't burn up the solenoid by having 100% duty cycle. when throwing the transfer case lever into LOW wit hte switch off, i get 2 LOw. if i want 4 low, i just flip the switch, and vac passes through the solenoid and the system works as originally designed.

works great and cost me nothing as I had the mitsu part just sitting around anyway.
anybody have any questions, just let me know.
the boost control solenoid can be used from 90-99 mitsu eclipse turbo, plymouth laser turbo, eagle talon turbo and a few others but these will be the easiest to find.
fyi, the fuel pressure solenoid can also be used. you 'll find this up by the fuel rail in a factory turbo car. the boost solenoid will be on teh passenger side under the airbox.

her's a pic of my install: