Dorman 599-113 Transfer Case Control Module

Transfer Case Control Module Replacement

Restore transfer case control operation with this Dorman replacement module, Part Number 599-113. It is built to match the function and performance of the original module on specific Chevrolet and GMC 4x4 applications, including push-button shift systems with the NP8 transfer case.

• Replacement transfer case control module for electronic 4WD operation
• Black connector color with pin terminal type
• Direct-fit service part for select push-button shift transfer case systems
• Package contents: transfer case control module
• Interchange reference: 12590220

Vehicle Fitment

• Fits 2002-2005 Chevrolet Trailblazer, N/A, w/RPO Code NP8 (2 Speed, Push Button Shift, Transfer Case); Four Button Selection Switch
• Fits 2002-2005 Chevrolet Trailblazer EXT, N/A, w/RPO Code NP8 (2 Speed, Push Button Shift, Transfer Case); Four Button Selection Switch
• Fits 2002-2005 GMC Envoy, N/A, w/RPO Code NP8 (2 Speed, Push Button Shift, Transfer Case); Four Button Selection Switch
• Fits 2002-2005 GMC Envoy XL, N/A, w/RPO Code NP8 (2 Speed, Push Button Shift, Transfer Case); Four Button Selection Switch
• Fits 2004-2005 GMC Envoy XUV, N/A, w/RPO Code NP8 (2 Speed, Push Button Shift, Transfer Case); Four Button Selection Switch

Detailed Description

Dorman 599-113 is a transfer case control module replacement for select Chevrolet Trailblazer, Trailblazer EXT, GMC Envoy, Envoy XL, and Envoy XUV models equipped with RPO code NP8 and a four-button selection switch. If the original module is no longer controlling transfer case operation correctly, this replacement restores the same core function and performance expected from the factory unit.

This part cross-references 12590220 for the same application. The black connector and pin terminal layout support a straightforward electrical match to the original configuration on the listed vehicles.

Common Problems It Can Address

• Transfer case shift buttons do not respond
• 4WD mode selection is inconsistent or unavailable
• Electronic transfer case control faults
• Loss of communication between the switch and transfer case system
• Original module failure on NP8-equipped vehicles

Installation Notes and Tips

Verify the vehicle has RPO code NP8 and a four-button selection switch before ordering. Confirm connector style and terminal layout against the original module, and inspect related wiring, switch inputs, and transfer case components during diagnosis so the replacement module is installed into a known-good system.

Quality Assurance

Dorman supplies this module as a cost-effective OE-style replacement for the original transfer case control module on the listed applications. It is intended to provide the same function and performance as the factory part on compatible Chevrolet and GMC vehicles.