Beginning at the start of production for 2009 model year, General Motors replaced the external NSBU switch with an Internal Mode Switch (IMS).  They also eliminated the 3-2 downshift solenoid and 3-2 downshift valve and spring from the valve body.


Internal Mode Switch greatly improved the reliability, with elimination of water intrusion.

Elimination of the 3-2 downshift solenoid improved 3-2 downshift feel and increased band durability.

Parts Affected:

1. DETENT SPRING AND ROLLER - Manufactured wider at the "fork" or roller end, to accommodate the Internal Mode Switch (IMS).

2. MANUAL SHAFT - Now has flats on the internal part of the shaft, and a hole through it for the added rolled pin, to accommodate the added IMS. 

3. PARKING ROD - Now manufactured with a "Flat" in the middle of the park rod that produces the clearance needed in all detent positions for the added IMS.


5. INTERNAL HARNESS AND CASE CONNECTOR - With the elimination of the pressure switch assembly, the TFT Sensor was relocated in the new internal harness assembly. With the addition of the IMS, the pin functions must also change in the case connector. New case connector pin functions and pin identification. New Internal Mode Switch connectors and pin functions. We have also provided you with a wire schematic from the internal components to the external case connector.

6. VALVE BODY CASTING - Valve body is now cast shut where the 3-2 downshift solenoid was previously located and the pressure switch side of the valve body is no longer configured for the pressure switch.

7. SPACER PLATE - The valve body spacer plate also required elimination of the holes for the 3-2 downshift line-up and now has the gaskets molded to both sides of the plate.  They also eliminated the two snap-in screens and installed three new flat screens molded in with the valve body gaskets.


The new design Park Rod is the only piece that can be used to back service previous models and the previous Park Rod "cannot" be used on 2009 models.  None of the remaining parts listed above will interchange with previous design level parts.


If you found this quick tip to be helpful, let us know below. If you need technical help from one of our tech experts, give us a call at 1-800-245-7722 and we will be more than happy to assist in getting that job done and the customer out the door!

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