Allison 1000 5 Speed NSBU Switch Connector, 2001-2004 GM 6.6L Duramax LB7

Allison 1000 5 Speed NSBU Switch Connector

For 2001, 2002, 2003, 2004 GM 6.6L Duramax LB7

One of the most common problems with the Allison transmission is 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
  
  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 reason that PSM codes may set is that the NSBU switch and the internal PSM switch "look at each other" and "compare readings" Basically, the NSBU switch lets the TCM know what gear position that you, the driver, have selected. The PSM has the job of telling the TCM what gear the transmission is in based on hydraulic inputs. If the data received from the PSM and the NSBU do not agree, the above mentioned trouble codes may set. The NSBU is subject to water contamination and will allow the switch to give faulty readings.