I have a 1998 Pontiac Grand Prix GT (3.8L) with an automatic trans (151K miles). Everything was great until yesterday. The transmission shift through all the gears normally, but will not shift into OD. It will make a bit of growling noise when it tries to shift to OD. The noise is not very loud, however easily detectable with the radio off. Any ideas of the cause? Is there any easy fix is this a complete re-build?

It sounds like an internal mechanical problem. Common cause of no 4th - OD or dropping out of OD is the 4th clutch shaft. The splines strip. You may need a rebuild. Other possibility is the shift solenoids not working properly.

Thanks for the feedback. Is there a test for the shift solenoids? Is there a seperate solenoid for each gear?

There are 2 shifts solenoids. 1-2 and 2-3. Both are used to get 4th OD and work in the form of a logic gate. 1-2 is energized and 2-3 is de-energized.

Other than a DTC code possibly indicating a solenoid is bad you can ohm the solenoid(s) coil resistance at the 20 way umbilical connector.

There are 2 shifts solenoids. 1-2 and 2-3. Both are used to get 4th OD and work in the form of a logic gate. 1-2 is energized and 2-3 is de-energized.

Other than a DTC code possibly indicating a solenoid is bad you can ohm the solenoid(s) coil resistance at the 20 way umbilical connector.

I appreciate the help. Do you have the pinout for the 20 way umbilical connector? Or do you know the connections for the two solenoid coils?

If you can find a picture you need pin "E" 12v power "A" SS1 and "B" SS2 they should be 20-25ohms. So you would put the DVM prob on "E" & put the other prob on "A" should be 20-25ohms do the same for "B". If all your other gears are fine its more than likely your 4th shaft. If you look at the connector the first pin in the upper left is "A" then "B" then "C" then "D" then drop down a line and go back to the left thats "E" and so on. These are the male pins on the transmission case.