P0787
UniversalShift Timing Solenoid A low
Medium SeverityThis code indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) has detected a low voltage condition in the circuit for Shift Timing Solenoid A. This typically means the transmission is having trouble regulating the timing of its gear shifts, leading to noticeable driving issues.
⚠️ Before You Begin (Safety First)
Always allow the engine and transmission to cool before working on any components to prevent burns. Disconnect the battery before performing any electrical inspections or repairs to avoid accidental shorts or shocks. Use appropriate jack stands if lifting the vehicle.
Common Symptoms
- Check Engine Light illuminated
- Hard shifting
- Delayed shifts
- Transmission slipping
- Inability to shift into certain gears
- Vehicle stuck in a single gear (limp mode)
Common Causes
- Faulty Shift Timing Solenoid A
- Open or short circuit in the solenoid wiring or connector
- Low transmission fluid level
- Contaminated transmission fluid
- Faulty Transmission Control Module (TCM) or Powertrain Control Module (PCM)
Frequently reported on: General/Universal
Diagnostic Steps
- Check transmission fluid level and condition. Top off or change if necessary.
- Visually inspect the wiring harness and connector for Shift Timing Solenoid A for any signs of damage, corrosion, or loose connections.
- Clear the code with an OBD-II scanner and test drive the vehicle to see if it returns.
- If comfortable, access the transmission pan (if necessary) to visually inspect the solenoid for any obvious damage. (Note: This is an advanced step).
- Consider having the solenoid circuit tested with a multimeter for proper resistance and voltage.
- If all external checks fail, suspect a faulty solenoid or internal transmission issue.
- If symptoms persist, professional diagnosis is recommended.
👨🔧 When to Call a Professional
If you've checked the basic wiring and fluid levels and the issue persists, or if you're uncomfortable dropping the transmission pan, it's highly recommended to consult a professional transmission specialist. Complex internal transmission diagnostics and repairs require specialized tools and expertise.
Commonly Asked Questions
What does 'Shift Timing Solenoid A low' mean?
It means the computer controlling your transmission is seeing a lower than expected electrical signal from or to the 'A' shift timing solenoid, which is responsible for regulating when your transmission shifts gears.
Can I drive my car with a P0787 code?
It is not recommended. Driving with this code can lead to poor shifting, transmission damage, and potentially leave you stranded. Address the issue as soon as possible.
What are the most common fixes for P0787?
The most common fixes involve checking or replacing the faulty shift timing solenoid, repairing damaged wiring or connectors, or ensuring correct transmission fluid levels and quality.
Is replacing a shift solenoid a difficult DIY repair?
It can be. Often, accessing and replacing a shift solenoid requires dropping the transmission pan, which involves draining fluid, potential mess, and careful reassembly. It's generally considered an advanced DIY task.
Could a P0787 code indicate a need for a new transmission?
While it could lead to transmission damage if ignored, a P0787 code usually points to a specific component failure (the solenoid or its circuit) rather than requiring an entire transmission replacement. Early diagnosis and repair are key to avoiding more costly repairs.