My 97 Maxima SE won't pass inspection due OBD II code of P 745 - pressure control solenoid. It has something to due with air intake. Last week I replaced the starter and had to remove some of the air intake parts to due it. Any ideas?? Thanks, K
The pressure control solenoid is in your automatic transmission. It's a solenoid-operated valve that regulates line pressure. It causes the transmission to shift hard and fast, soft and slow, or somewhere in between. Most pressure control solenoids use a pulse-width modulated signal with a variable duty cycle.
The solenoid may fail mechanically (stuck open or stuck closed) or electrically (shorted to power, shorted to ground, or open). When the relevant OBD module detects a problem with the pressure control solenoid, the "Check Engine" light illuminates, and other transmission default operating conditions are usually enabled. Depending on the transmission, the torque converter lock-up clutch may be disabled, certain gear ranges may be disabled, etc.
Unfortunately, P0745 is the catch-all code for a general pressure control solenoid failure. Other DTC numbers, such as DTC P0748 will tell you up front that it's an electrical failure mode.
The pressure control solenoid is diagnosed with a breakout box attached to whatever module (TCM, PCM, VCM, or ECM) controls the transmission. First, check for shorts, opens, and specified resistance (don't forget to correct for temperature) with a DVOM. If nothing is found, use the breakout box to disable and enable the solenoid while driving the car. The transmission shifting behavior should alternate between shifting hard and fast to soft and slow. (Don't let the transmission slip excessively.) If the transmission shifting behavior doesn't change, the valve is faulty (stuck open or closed). If the shifting behvior of the transmission does change, the module that controls the transmission is faulty.
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