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.
When a transmission solenoid is stuck on, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is very dirty, it is recommended to change the transmission fluid and if possible, remove the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a transmission mechanical failure, and that the transmission will need to be rebuilt or replaced.
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 P0742
The cost to diagnose the P0742 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 Torque Converter Clutch (TCC) pressure control solenoid is part of the control solenoid valve assembly which has no serviceable parts. The TCC pressure control solenoid is a normally low-pressure control solenoid. The TCC pressure control solenoid regulates the transmission fluid to the TCC regulator valve in the lower valve body and the TCC control valve in the pump cover. When vehicle operating conditions are appropriate to apply the converter clutch, the Transmission Control Module (TCM) will increase TCC pressure control current flow (duty cycle) to the TCC solenoid. The TCC pressure control solenoid directs fluid pressure to move the TCC control valve to the apply position and moves the TCC regulator apply valve to the regulating position. The TCC regulator valve regulates TCC apply fluid pressure proportional to TCC solenoid pressure. When the TCC is fully applied, the engine is coupled directly to the transmission. TCC release is accomplished by the Transmission Control Module decreasing current flow to the TCC pressure control solenoid. This results in decreasing the applied pressure which allows the TCC control valve to move to the release position. The Transmission Control Module calculates torque converter slip speed based on engine speed and transmission input shaft speed.
The Diagnostic Trouble Code (DTC) will be set when the CM detects the TCC slip between −50 and +13 RPM for 6 s when the TCC is commanded OFF.
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