P0785 code definition
The appearance of the P0785 code means that the PCM detected an abnormal malfunction in the shift/time solenoid.
What the P0785 code means
The transmission control module, or TCM, uses data from the shift/timing solenoids to manage hydraulic fluid transfers between circuits, and to perform changes in transmission gear ratios in order to accelerate, decelerate, optimize fuel efficiency, and maximize engine performance. If the data from the shift/timing solenoid does not match the manufacturer’s specifications for the particular situation or command, the TCM will assume that there is a malfunction, and alert the PCM to store the P0785 code.
What causes the P0785 code?
The most likely causes of the P0785 code include:
- Faulty shift solenoid
- Blocked internal transmission fluid passages
- Mechanical failures in the transmission
- Low transmission fluid
- Dirty transmission fluid
- Faulty TCM or PCM
- Open or shorted solenoid valve harness
- Poor electrical connection in the shift/timing solenoid valve circuit
What are the symptoms of the P0785 code?
The symptoms of the P0785 code can vary significantly. In some cases, the only symptom will be the illumination of the Check Engine Light. In other cases, the transmission may fail to shift into or out of certain gears, [shifting may be harsh], the transmission may slip or overheat, and the vehicle’s fuel efficiency may suffer. It is also likely that the PCM will store other shift solenoid codes along with the P0785 code.
How does a mechanic diagnose the P0785 code?
In repairs where the transmission fluid could be causing an inaccurate data reading, the first step a mechanic should take is to inspect the transmission fluid. Low transmission fluid should be remedied. Dirty transmission fluid should be drained and replaced. The code should then be cleared from the PCM, and the system should be retested. If the code returns, the mechanic has successfully diagnosed a problem within the shift/timing solenoid or related components.
Common mistakes when diagnosing the P0785 code
In many cases, shift solenoids are replaced when the malfunction actually lied in the shift solenoid circuitry. It is important to test all electrical components before replacing any parts in order to ensure that this code will not return shortly after repairs.
How serious is the P0785 code?
If the P0785 code is detected by an OBD-II scanner, the issue needs to be addressed right away. While in some cases, there may be no noticeable symptoms, the transmission may still experience malfunctions. If this issue is left unaddressed, the vehicle could become inoperable.
What repairs can fix the P0785 code?
There are many ways that a technician can address a P0785 code. These methods may include:
- Replacing a faulty shift solenoid, or shift solenoid pack.
- Clearing blocked internal transmission fluid passages.
- Addressing any mechanical failures in the transmission.
- Remedying low transmission fluid.
- Flushing and replacing dirty transmission fluid. In some cases, the entire transmission may need to be disassembled and cleaned in order to rid the system of dirty transmission fluid.
- Replacing a faulty TCM or PCM.
- Replacing or repairing an open or shorted solenoid valve harness.
- Repairing a poor electrical connection in the shift/timing solenoid valve circuit.
- Replace a defective pump in the transmission.
After each repair is performed, it is important to clear the code from the PCM and retest the system. If the code does not return, it may mean that the mechanic has performed the right repair to fix the issue. If it does return, it indicates that the problem is ongoing. This procedure helps narrow down the true cause behind the P0785 code.
Need help with a P0785 code?
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