GMPP LS3/7 Controller (E67) No Communication

I hope someone here can help with this. We have a customer that brought us his 89 Fox Body Mustang with a Blueprint Engine 427 LS. He did all the wiring and install himself and the car starts, runs and drives. The issue at hand is that I am not able to communicate to the PCM. I have tried EFI Live, and SCT 3416, and HP Tuners... all fail. The V2 returns back an error of "vehicle not connected" when attempting to read DTC codes when not in pass thru mode. I have verified continuity from Pins 6 and 4 on the OBD2 port back to 33 and 53 on the gray connector according to the EFI Live bench harness instructions and re-confirmed in the GMPP literature supplied with the controller kit.

According to the customer there were only a few wires to hook up: grounds, battery 12v, a CEL light (which I have yet to find), and a keyed 12v (pink wire) which is connected to the ignition switch.

Thanks in advance and any help is appreciated.

If that's the error, you're not getting the correct power/comms at the OBDII port.

You need the grounds, +12V constant, +12V switched, CAN-, and CAN+ to communicate with the ECM. If any of those arent connected correctly or a fuse is blown, you wont be able to get into the ECM.

Thanks for the reply. I was able to get it sorted. Previously I had verified continuity of CAN +/- by poking through the insulation of the wires as they fed into the gray PCM connector. This time I decided to disassemble the connector completely and back probe the pins. Upon doing so pin 53 popped out (thanks GMPP), so I verified continuity, re-seated pin 53 and lo and behold communication.

Time to make some horsepower now!

Glad to hear it was a simple fix.