lt170chevelle

iTrader: (2)

I have a 98 blazer and a 2000 6.0 motor and harness. I just changed the transmission and noticed during a log that neither my MAP sensor nor O2 sensors are reading at all.
Does anybody know if they share a common ground or supply?
This is a factory harness that wasnt lengthened.
Im thinking mybe i pinched a wire from putting the intake back on but not likely.

gectek

iTrader: (2)

They are all mostly in the back part of the harness. You could have pinched the harness in the bellhousing when you did the trans swap. Easiest way to check is to check the grounds on the O2 sensors. Just a quick continuity check from the black wires to any ground should show them connected. After that check power with key on on the other 2 terminals. All map sensor wires should go back to the PCM. SO check cont on them and you should get a better idea. Key on should give you voltage on gray wire. 5V. The others work off the sensor.

jimmyblue

iTrader: (11)

What do you mean by "not reading"?

Reading 0V might be ENG SEN fuse, esp. if MAF is also
out. Sensor heater wires seem to get shorted during
trans work, a lot.

A missing ground would make the MAP sensor drift
up to 5V.

O2 sensors will generate their own voltage, at least
if you get them hot and rich enough.

But no reading -at all- is more like a scan tool brain
fart.