P0788 Shift Timing Solenoid A Signal High

P0788 – OBD-II Trouble Code Technical Description

Shift Timing Solenoid A High

What does the fault code mean P0788?

Common transmission diagnostic trouble code (DTC) P0788, commonly applied to OBD-II vehicles with automatic transmission, is related to the shift timing solenoid. These solenoids control the flow of hydraulic fluid (ATF) in the transmission for smooth gear changes according to driving needs. When the engine control module (ECM) detects a high electrical value in the solenoid circuit, the malfunction indicator lamp (MIL) illuminates. The electronic engine control system (ECU) cannot control shift timing and determine the current gear, which can lead to transmission problems. It should be noted that automatic transmissions are complex systems, so it is better to contact professionals for repairs.

Related codes include P0785, P0786, P0787, and P0789. If you have a flashing trouble code P0788, there is no need to worry. We offer a wide range of spare parts at affordable prices. Visit our store to get the parts you need to keep your vehicle running smoothly.

Possible reasons

Possible causes of a high voltage Shift Timing Solenoid A problem may include:

• Faulty wiring harness
• TCM malfunction
• Shift timing solenoid malfunctions
• Automatic transmission fluid problems
• Insufficient ATF level
• Some problems related to ECM
• Contact/connector problems (corrosion, melting, broken retainer, etc.)
• Lack of transmission fluid
• Contaminated/old transmission fluid
• Damaged connectors and/or wiring
• Broken shift timing solenoid
• Blocked fluid passage inside the gearbox
• TCM or ECU malfunction

What are the symptoms of a fault code? P0788?

Symptoms of a P0788 trouble code may include:

• Erratic gear shifting
• Slipping transmission
• Hard or abrupt gear changes
• Ineffective shift times
• Poor handling
• Poor acceleration
• Decline in overall performance
• Unpredictable switching
• Unusual acceleration
• Sluggish mode
• Abrupt, erratic shifts
• Slip
• Transmission stuck in gear
• The car does not move in gear
• Increased fuel consumption
• Transmission overheats

How to diagnose a fault code P0788?

If the transmission fluid contains dirt, sediment, or metal debris, the solenoids may not function properly. It could also be a bad wiring harness, a faulty TCM, or a problem with the shift timing solenoid. It is important to check the ATF level and condition before taking further action. If the fluid is contaminated, the gearbox can be flushed.

If there are no obvious maintenance problems, you should check the wiring and connectors for damage and corrosion. After this, it is worth inspecting the gear shift timing solenoid in accordance with the manufacturer's instructions. If the problem persists, the problem may be with the valve body.

Before troubleshooting, check the Technical Service Bulletins (TSB) for your vehicle. Checking the ATF should be the first step. If the fluid is dirty, has a burnt odor, or is an unusual color, replace it. It is recommended to check the solenoid and its harnesses for damage or leaks.

It is recommended that you contact a certified technician to access the internal solenoid. When testing a solenoid, you can use a multimeter to measure the resistance between its contacts. It is also recommended to check the electrical continuity from the TCM.

Diagnostic errors

Common errors may occur when diagnosing DTC P0788. Some of these include not paying enough attention to the condition of the transmission fluid, not checking the wiring and connectors for damage or corrosion, and not properly detecting the shift timing solenoid. It is also possible to miss checking the valve body and not pay attention to the Technical Service Bulletins associated with your specific vehicle make and model.

How serious is the fault code? P0788?

Trouble code P0788 indicates that the Shift Timing Solenoid A signal is high. This can cause shifting problems, poor handling, rough vehicle handling, and other transmission-related problems. Although this is not a critical emergency, it is important to take this code seriously and correct the problem immediately to avoid possible transmission damage and additional vehicle problems.

What repair will help eliminate the code? P0788?

1. Checking and replacing transmission fluid.
2. Cleaning or flushing the gearbox.
3. Checking and replacing damaged wires and connectors.
4. Repair or replace the shift timing solenoid.
5. Diagnosis and repair of the TCM (Transmission Control Module) or ECM (Engine Control Module).
6. Check and eliminate possible transmission fluid leaks.
7. Check the valve body for possible malfunctions.

What is P0788 Engine Code [Quick Guide]

P0788 – Brand-specific information

Code P0788 refers to problems with the shift timing solenoid A. Here are some makes of vehicles that this code may affect:

1. Chevrolet/Chevy – A generic marketing brand for automobiles manufactured by General Motors Company.
2. Volvo is a Swedish car manufacturer.
3. GMC – A brand of cars and trucks manufactured by General Motors.
4. Saab is a Swedish car brand founded by Saab Automobile AB.
5. Subaru is a Japanese car manufacturer.
6. VW (Volkswagen) – German automaker.
7. BMW – Bavarian cars manufactured by Bayerische Motoren Werke AG.
8. Toyota is a Japanese automaker.
9. Ford is an American automaker.
10. Dodge is an American manufacturer of automobiles and other commercial vehicles.