GM Service Manual Online
For 1990-2009 cars only

When the gear selector lever moves to the Neutral (N) position from the Reverse (R) position, the following changes to the hydraulic and the electrical systems in the transmission occur:

Reverse Clutch Releases

Manual Valve

Mechanically controlled through the gear selector lever, the manual valve directs line pressure into the PRND43 and the PRND4 circuits. PRND4 fluid then passes around a valve land and enters the PRN fluid passage.

Internal Mode Switch (IMS)

The internal mode switch (IMS) is a sliding contact electrical switch assembly that corresponds to the PRNDL position selected. Each of the PRNDL positions has a unique ground pattern on the five wires from the TCM. The IMS consists of two major components: The housing, which houses the tracks and makes up the stationary contacts. The Insulator assembly makes up the moving contacts and is linked to the detent lever. The range detection is accomplished by securing the moving contacts of the IMS to the detent lever. When the driver selects a PRNDL position, the detent lever inside the transaxle rotates. This slides the IMS moving contacts which in return grounds the five wires in a unique pattern for each gear selection corresponding to the PRNDL position selected. The IMS is electrically connected by six wires (five of which the TCM supplies voltage to and one wire that is a common ground) to the transaxle pass through connector.

Neutral - Engine Running


Object Number: 1217584  Size: FS
Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Control Valve Body Fluid Passages (Case Cover Side)
Case Cover Fluid Passages (Control Valve Body Side)
Case Cover Fluid Passages (Control Valve Body Side)
Case Cover Fluid Passages (Control Valve Body Side)
Case Cover Fluid Passages (Control Valve Body Side)