New LB7 Duramax NSBU Switch w/ Connector Repair Kit | 29540479, 29540472, 15179957, 15179799 | 2001-2004 GM Duramax 6.6L w/ Allison 1000

Includes:

• 1x NSBU Switch, LB7, 2001-2004 Allison 1000
• 1x NSBU Connector Repair Kit, LB7, 2001-2004

New NSBU Switch w/ Connector Repair Kit for 2001-2004 GM Duramax 6.6L LB7 w/ Allison 1000.

Includes a connector set with color-coded wires for easy installation. It comes with OE-style connectors and around 12 inches of lead wire.

A common issue with the Allison transmission is the failure of the Neutral Safety Back Up switch.

Some of the symptoms of failure include but are not limited to:

• No start condition
• Gear shift indicator on dash not following properly
• Trans stuck in limp mode or fail safe
• DTC's set indicating pressure switch codes

This switch easily installs with just common hand tools. How does it work and why does it cause my transmission not to shift?

The vehicle features a column-style shift selector. Along with the column shifter, the Neutral Safety Back Up (NSBU) switch is a key component, mounted on the transmission’s selector shaft. This switch transmits gear position information to the Transmission Control Module (TCM). Installed externally on the transmission housing, the NSBU switch detects the angular position of the shift selector shaft and relays this data to the TCM, ensuring that various vehicle control functions align with the selected gear. The neutral signal output from the NSBU switch serves as a confirmation that the transmission is in NEUTRAL or PARK before the engine starter engages.

Common trouble codes associated with NSBU failure include:

• DTC P0708, Neutral start/backup (PNP or NSBU) switch
• DTC P0847, Pressure Switch Manifold (PSM)
• DTC P0872, Pressure Switch Manifold (PSM)
• DTC P0875, Pressure Switch Manifold (PSM)
• DTC P1711, Pressure Switch Manifold (PSM)
• DTC P1713, Pressure Switch Manifold (PSM)
• DTC U1000, Serial Data Communications
• Blank PRNDL Display
• Flashing PRNDL Display
• Slow or No Engagement of Automatic Transmission

The PSM codes may be triggered because the NSBU switch and the internal PSM switch continuously compare their readings. The NSBU switch informs the TCM of the gear position selected by the driver, while the PSM communicates the actual gear position based on hydraulic inputs. If there is a discrepancy between these signals, the system may register the previously mentioned trouble codes. Additionally, the NSBU switch is vulnerable to water contamination, which can cause it to send inaccurate signals.