Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Electronic System Description: Notes
Transmission shift scheduling relies on the following:
- Accelerator pedal position
- Engine speed and acceleration
- Vehicle speed and acceleration
- Engine torque
- Converter state as defined by engine speed
- Turbine speed
- Transmission range sensor position
- Brake status
- Speed control status
- Transmission fluid temperature
- Engine coolant temperature
The powertrain control module (PCM) and its input/output network control the following transmission operations:
- VFS (shift feel)
- Shift timing
- Line pressure (engagement feel)
- Torque converter clutch operation
The transmission control is separate from the engine control strategy in the PCM, although some of the input signals are shared. When determining the best operating strategy for transmission operation, the PCM uses input information from certain engine-related and driver demand-related sensors and switches.
The following components are used to determine engine torque information for the transmission control strategies:
- Crankshaft position (CKP) sensor
- Camshaft position (CMP) sensor
- Barometric pressure (BARO) sensor
- Mass air flow (MAF) sensor
- Manifold absolute pressure (MAP) sensor
- Engine oil temperature (EOT) sensor
- Air conditioning pressure (ACP) switch
- Exhaust gas recirculation (EGR) valve
- Injection pressure regulator (IPR)
- Manifold air temperature (MAT) sensor
Any concerns with the engine sensors must be diagnosed and repaired before proceeding with diagnosis of the transmission components. See INTRODUCTION - GASOLINE and/or INTRODUCTION -- 6.0L DIESEL articles for engine component diagnosis.
Using all of these input signals, the PCM can determine when the time and conditions are right for a shift, or when to apply or release the torque converter clutch. It will also determine the best line pressure needed to optimize shift feel. To accomplish this, the PCM uses output solenoids to control transmission operation.
The following provides a brief description of each of the sensors and actuators used by the PCM for transmission operation.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.