P0750 OBD-II: Shift Solenoid "A"
P0750 Severity
Should you fix P0750 yourself?
Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.
Proper diagnosis will save you time and money on unnecessary repairs.
Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.
What causes OBD-II fault code P0750?
The Transmission Control Module (TCM) uses shift solenoids to control the hydraulic pressure in the transmission which is needed to apply the various clutch packs in the transmission that provide the different gear ratios needed to efficiently propel the vehicle down the roadways. When the TCM detects a shift solenoid is not performing as desired, it will set code P0750.
What Does P0750 Code Mean?
OBD-II Code P0750 is defined as a Shift Solenoid A Malfunction
The purpose of the automatic transmission is to match the engine's optimum power and torque characteristics to the driver's desired rate of acceleration and speed by auto-selecting different gear ratios or 'speeds' to power the wheels. Shift solenoid A enables the transmission to shift from 1st gear to 2nd gear. It does this by re-directing the flow of the transmission fluid which changes the position of the shift valves in the valve body.
When the code P0750 is set in the Powertrain Computer, it means that the Powertrain Computer or PCM is not seeing the specified rpm change that occurs during a shift from 1st to 2nd gear.
Symptoms
- Check Engine Light will illuminate
- Vehicle will not shift from 1st gear to 2nd gear properly
- Decrease in fuel economy
- In unusual cases, there are no adverse conditions noticed by the driver
- In some cases, there may be performance problems and possibly misfire-like symptoms
Common Problems That Trigger the P0750 Code
- Defective Shift Solenoid
- Defective Shift Solenoid wiring or connector
- Defective Valve Body
- Dirty transmission fluid that restricts the hydraulic passages
Common Misdiagnoses
- Engine Misfire problem
- Driveline problem
Polluting Gases Expelled
- HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
- CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas
- NOX (Oxides of Nitrogen): One of the two ingredients that, when exposed to sunlight, cause smog
P0750 Diagnostic Theory for Shops and Technicians
When diagnosing a P0750 code, it is important to record the freeze frame information and then to duplicate the code setting conditions with a test drive at speeds around 15-35 mph. Start out from a dead stop and gently accelerate. Watch the scan data to see if the PCM is commanding the solenoid to shift. If the PCM is giving the 1-2 shift command and the vehicle does not properly shift from 1st to 2nd gear, then you have verified a problem that could set the P0750 code. Next step is to start doing pinpoint tests i.e voltage drops and continuity tests of the shift solenoid. I generally back probe the wiring harness so I don't have to disassemble the transmission. A P0750 may mean that the solenoid is electrically within spec but may not be working correctly. And, ALWAYS check the condition of the fluid. Is it dirty, brown and burnt or is it that clear cranberry color?
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