Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
There is a factory service bulletin for the following Buick Models:
2001-2005 Buick LeSabre
2001-2005 Buick Park Avenue
2002-2007 Buick Rendezvous
2002-2007 Buick Rendezvous AWD
2005-2007 Buick Terraza
2005-2007 Buick Terraza EXT
2005-2007 Buick Terraza 4WD
2005-2008 Buick Allure (Canada Only)
2005-2008 Buick LaCrosse
2006-2008 Buick Lucerne
Buick Factory Service Bulletin OBDII Code P0842
The cost to diagnose the P0842 BUICK code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
The Transmission Fluid Pressure (TFP) switch 1 is part of the control solenoid valve assembly, which has no serviceable parts. The Transmission Control Module (TCM) supplies a signal circuit to the TFP Switch 1. The TFP Switch 1 has an internal case ground. TFP Switch 1 is normally closed or LOW. When oil pressure is present at the TFP Switch 1, the switch is open or HIGH. The normally high clutch pressure control (PC) solenoid 2 controls pressure to the 3-5 reverse clutch regulator valve. The TCM monitors the TFP switch 1 to determine the position of the 3-5 reverse clutch regulator valve. When the 3-5 reverse clutch is commanded OFF, pressure is present on the TFP switch 1. When the 3-5 reverse clutch is commanded ON, the 3-5 reverse clutch regulator valve moves and pressure to the TFP switch 1 is exhausted through the 3-5 reverse clutch regulator valve. The Diagnostic Trouble Code (DTC) will be set when the TCM detects that the TFP switch 1 signal voltage remains LOW after the 3-5-R clutch transitions from a HIGH pressure state to a LOW pressure state. The TCM counts each incident. The DTC sets when 25 counts are accumulated.
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