No vehicle speed, but trans shifts fine

[2000_SS]

Doing a little tuning on a '78 camaro with a truck 6.0 / 4L80e in it. It has LS3 heads, intake, and electronic TB. First off, the car overall is rough and needs a lot of wiring and some little issues resolved which makes me nervous. The engine wiring, however, is a Speartech harness, and SHOULD be good. In the scanner, vehicle speed shows 0mph all the time, but the transmission seems to shift as commanded just fine into all gears. Is it possible that the VSS and ISS wiring is wrong? The harness was supposed to be complete and correct from Speartech, no other wiring necessary. I can see the ISS and VSS sensors are installed and connected, but i have not yet checked the pins at the PCM to verify they're correct.

I was just confused that the PCM wasn't seeing vehicle speed, yet the trans shifted correctly. Any ideas?

[dermotw]

Speedo entries look a bit odd. I don't know much about autos, but e.g. the trans revs/mile is 3x what mine is, and mines got a 4.11 axle... couple of the others are more or less double mine as well.

kr D.

[2000_SS]

Speedo entries look a bit odd. I don't know much about autos, but e.g. the trans revs/mile is 3x what mine is, and mines got a 4.11 axle... couple of the others are more or less double mine as well.

kr D.

I'll double check those values tonight against a stock file. I'm working off of a mail order tune from somebody that I'm 99.999% certain they now what they're doing.

[2000_SS]

VSS pulses per mile corrected to 107,354. Everything else in the speedo section seems correct to me and is verified using the Bluecat trans tool. Even if all the values were arbitrary numbers, there would still be something other than "0mph" in the scanner. I think i'm going to go ahead and trace the VSS/ISS wiring and maybe test the sensors themselves somehow