2005 Pontiac Grand Prix GXP LS4 DoD 4T65E TAPShift powertrain swap into a Pontiac Fiero



Installed the APP (accel pedal position) sensor and gas pedal assy...

The LS4 ECM utilizes a fly-by-wire throttle control system (aka: Electronic Throttle Control; ETC).  The ETC system consists of 3 major components: 1) the ECM or PCM;  2) The APP sensor and gas pedal assy;  and 3) the ETC control module - throttle body.


The ECM on this engine also wants to see a BVB (brake vacuum booster) pressure sensor. I presume it is primarily used for the flight recorder function present in most newer GM vehicles. The brake booster had to be removed from the car so I could drill the hole for it and make sure the metal shavings didn't fall down inside the booster.  I probably didn't need to install this sensor as I could have turned off the trouble code associated with it in the ECM's programming, but since I had to remove the brake booster mounting bolts for the installation of the BPP sensor, I figured I would just install it anyway.


The ECM and TCM receive a stop lamp switch signal directly from the BCM. The BCM activates the stop lamp switch output to turn on the brake lights (and signal the ECM/TCM) when a certain signal is seen coming from a sensor mounted on the brake pedal assy. The brake pedal position (BPP) sensor works much the same as a throttle position sensor in that it has a lever actuated by movement of the brake pedal. Mating the BPP sensor to the Fiero brake pedal is easy as long as you can find a location where it won't interfere with the brake linkage or steering column; which passes very close to the brake pedal hardware. I found such as location as noted in the pictures below...



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