1993 4l80e
I installed a 1993 4l80e behind my 6.0 using an 2001 pcm. I have a PSI harness built for the 4l80e. The transmission will not shift. Not sure if it is taking off in 1st or 2nd but it is not shifting. I know that pre 1996 4l60e transmissions are not compatible with ls pcm's. Is this what i am dealing with?
I installed a 1993 4l80e behind my 6.0 using an 2001 pcm. I have a PSI harness built for the 4l80e. The transmission will not shift. Not sure if it is taking off in 1st or 2nd but it is not shifting. I know that pre 1996 4l60e transmissions are not compatible with ls pcm's. Is this what i am dealing with?
Very, very common on swaps is no 12 volts, ground problems, and pcm signal problems.
Starting off in 2nd or stuck in second is limp mode, it happens when the transmission has no electrical.
And you're not the first one with a high dollar, premade, plug and play harness that didn't play.
you have the new plug, don't think you could plug into it if the old case plug. To be sure, look at the
plug in the case, should have 4 contacts top row, 1 on the sec row, and 6 on the bottom. The contact
on the 2nd row should have the +12. On the bottom row, counting from the left, contacts 3, 4, 5 have
voltage, they go to the pressure switch. Your shifter moves the man. valve, which (when engine is
running) directs fluid to the pressure switch, depending which gear you selected, puts a ground out to shunt
the voltage, and tells the ECU what gear you commanded. If the ECU cant determine what gear
is wanted, it will go limp mode, 2nd and rev. 1994 they changed the force motor, and the spacer plate
got some diff holes, and the force motor also got a diff HZ #. How that affects things I don't know,
or if you need or have the new motor. The newer FM may be black.
Where did the transmission come from? Did you ever drive it before this swap?
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