Joined: Dec 2018

Posts: 1

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So we’ve got a 93 c4 corvette at the shop here and is in no shape or size stock anymore. The owner has a pro charger kit in it and engine work and a 4l60e or 4l80e trans. Obviously the ratios aren’t stock so the ecm can’t do the pulse per mile to speed conversion so it had to be equipped with a eztcu transmission controller so we can control the trans shift points. The eztcu has a handheld device which displays gear speed and rpm on its display. All of which are accurate . The handheld displays speed and is supposed to be spliced into the ecm speed output to the ccm. Which is spliced in correctly we are just losing the signal between the splice point and Ipc. We have sent out the ccm twice and the trans controller once to get checked out and have sent out the ipc all of which have returned to us with no issues. Ive been off and on this vehicle for quite some time so I can confirm we have continuity all throughout the circuit. Has anyone had experience with this kind of issue before?

To to confirm yes it was working prior to this and just stopped working one day and hasn’t started working since. Since the new controller has its own vss lines we aren’t using the oem lines. If we were to connect them to the vss the speed on the dash would jump from 25-52-150-220 mph.


Any any help or insight is much appreciated.

Also so does anyone know what the output from the ccm to ipc is for the vehicle speed sensor? I’m guessing it is one of the serial data lines but I’m unsure and any calling around doesn’t shed any light. Was hoping the guys over here could help me out.