Originally Posted by babywag
Online writeup info conflicts with GM info/wiring diagram.
E5 - says P/N switch swap B10, GM says it's for the transmission range signal "c"
E13 - says battery swap C16, GM says it's for the brake signal TCC function.
Note 2 = B+ BRAKE NOT APPLIED 0 VOLTS BRAKE APPLIED
F14 - not listed online, GM says TP reference
F15 - not listed online, GM says ignition feed splice
So me thinking (dangerous I know)
E5, and E13 should not be used/swapped.
F14, and F15 should be used.
Hoping tomorrow to mod my old harness and cross my fingers the pcm I picked up works?
Not sure about the p/n switch. I am running a manual trans, so I dont use one. Its my understanding that there is not one on the trucks these PCM's were used it. From what I read, the pcm uses data it gets from the transmission to know what gear its in. So unless you have a 4L60E or 4L80E, I would just leave that wire un hooked.
The brake signal was used for the TCC, from what I read it served no other purpose. The 7747 used two battery feed wires. 1 goes to E16, the other to E13. It works where when that pin has 12v, it means the brakes are off. When it gets no power on that pin, it means your on the brakes. So unless you have a trans with a electric TCC, just apply 12 volts to that pin.
F14. On the 7747, the 5 volt refrence for the TPS and MAP sensors are both fed off of pin C14. On the 7427, it has a seperate pin and wire for map and tps. I just hooked old pin C14 to pin E14, and left F14 with nothing on it. Works just fine.
F15, not sure. I dont have anything hooked there.
Also make sure you un hook and remove the knock sensor ESC module!! This is built into the memcal in the 7427. The knock sensor hooks directly to the pcm on pin B15. Attach your old wire B7 to that pin, then cut off the old plug from the esc module and attach the knock sensor wire (usally blue) to the signal wire (usally yellow with a stripe, I think red) This will connect the knock sensor to the pcm. You will also need to get the correct knock sensor. Get one for a 95 1500 with a 350 for a auto trans. The connector on it should be black, not white.
Have you done any tuning to it yet? If you dont turn off the auto trans controlls and error codes, and change a few other settings, its gonna be popping up error codes because its not seeing the transmission and the other stuff we dont use. I also inputted my timing table I built, from my old 7747 bin file into the bin file in the 7427. If your running a stock un modded chevy tune on that pcm, your probably not gonna run the best. Tuning is required to run the best.