Transmissions 4l60e
#3
Moderator
Have a trans shop hook up a scanner that can command the gears.
If the 3rd/4th cannot be commanded, you have a broken harness.
If all gears can be commanded, you either have a sensor problem or a bad PCM.
Have you scanned for codes?
As suggested, an engine code can cause the trans to act up.
If the 3rd/4th cannot be commanded, you have a broken harness.
If all gears can be commanded, you either have a sensor problem or a bad PCM.
Have you scanned for codes?
As suggested, an engine code can cause the trans to act up.