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Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 17022
Experience:  15 years GM master tech
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4l80e no shift, 2nd and reverse only

Resolved Question:

4l80e no shift, 2nd and reverse only
Submitted: 6 years ago.
Category: Chevy
Expert:  Gary replied 6 years ago.
Hi JACUSTOMER-lkkwwpgn-. Thank you for asking your question on JustAnswer. The other Experts and I are working on your answer. By the way, it would help us to know:

-What year is your Chevy?
-What model is your Chevy?
-How many miles are on your Chevy?
-What type of engine is in your Chevy?
-What have you already tried?

Thank you again for trusting us with your problem. Please reply as soon as possible so that we can finish answering your question.
Customer: replied 6 years ago.
1991 3500 with 7.4 engine appears to have 94 or later engine and trans, have been using truck 5 years. speedometer reads 168000. trans rebuilt, replaced a and b silenoil and tps. scan tool shows switches changing gears, but staying in 2nd gear. can feel some change when down shift manually. trans doing same be for rebuilt
Expert:  Gary replied 6 years ago.
ok turn the key on and unplug the big connector to the transmission.with a multi meter or test light see if the harness you unplugged had 12 volts at the pink wire.should be terminal B in this picture

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Customer: replied 6 years ago.
wire colors and terminal letters not matchijng up , terminal e is only pink and has 12v . b terminal is white has nothing
Expert:  Gary replied 6 years ago.
ok if the pink wire(yes it is terminal E im sorry i mistyped)has 12 volts either the computer is bad or the wiring is bad to the transmission or the wiring in the underside of the pan is bad.all the shift solenoids use that 12 volts then the other wires are controlled grounds to turn on and off the shift solenoids
Customer: replied 6 years ago.
there is a red wire that has 12 volts also
Expert:  Gary replied 6 years ago.
we are just concered with the pink at this point.that pink wire is the power side of those shift solenoids.if you have power and the solenoids are new then either there is a wiring problem or the computer is bad and not controling the ground to shift the solenoids
Customer: replied 6 years ago.
should th a and b terminal maintain grd at all times
Expert:  Gary replied 6 years ago.
NO they should not both be ground ALL the time
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