P0985
UniversalP0985 indicates that the Transmission Control Module (TCM) has detected a low voltage condition within the control circuit for Shift Solenoid 'E'.
Medium SeverityThe P0985 code means that your vehicle's transmission control module has detected a low voltage signal in the circuit that operates Shift Solenoid E. This issue can prevent the transmission from shifting correctly, potentially causing poor acceleration, harsh shifts, or the vehicle to enter a 'limp mode' to prevent further damage.
⚠️ Before You Begin (Safety First)
Always exercise caution when working with vehicle electrical systems and transmissions. Ensure the vehicle is securely supported on jack stands, the engine is off, and the battery is disconnected before performing any diagnostic or repair work, especially when dealing with hot transmission fluid.
Common Symptoms
- Check Engine Light illuminated
- Harsh or erratic gear shifts
- Transmission slipping
- Delayed engagement of gears
- Vehicle stuck in a single gear (limp mode)
- Poor fuel economy
- Transmission overheating
Common Causes
- Faulty Shift Solenoid E
- Open or short in the Shift Solenoid E control circuit wiring
- Corroded or loose electrical connectors
- Low or contaminated transmission fluid
- Internal transmission mechanical failure
- Faulty Transmission Control Module (TCM)
Frequently reported on: Various Makes and Models with automatic transmissions
Diagnostic Steps
- Check transmission fluid level and condition. Ensure it is at the correct level and not burnt or contaminated.
- Visually inspect the wiring harness and connectors leading to the transmission and Shift Solenoid E for any signs of damage, corrosion, or loose connections.
- Using a multimeter, test for continuity and proper voltage at the Shift Solenoid E connector (refer to your vehicle's specific wiring diagram).
- Test the resistance of Shift Solenoid E. An out-of-spec reading indicates a faulty solenoid.
- If possible, test the Shift Solenoid E directly by applying battery voltage to see if it actuates (ensure correct polarity and only if specified by a service manual).
- Clear the code and perform a test drive to see if the code returns.
👨🔧 When to Call a Professional
While basic circuit checks can be performed by a DIY mechanic, if the issue points to an internal transmission problem, such as a faulty shift solenoid requiring transmission removal or disassembly, it is best to consult a professional. Transmission internal repairs are complex and often require specialized tools and expertise.
Commonly Asked Questions
What is a shift solenoid?
A shift solenoid is an electro-hydraulic valve controlled by the Transmission Control Module (TCM) that directs transmission fluid pressure to engage specific gears, allowing the transmission to shift smoothly.
Can I drive with a P0985 code?
While your vehicle might still be driveable, it is not recommended. Driving with this code can lead to further transmission damage due to improper shifting, overheating, or being stuck in limp mode.
Is Shift Solenoid E difficult to replace?
The difficulty varies significantly by vehicle make and model. In some cases, it might be accessible from the transmission pan, while others may require significant disassembly or even transmission removal.
Does a P0985 always mean I need a new transmission?
Not necessarily. Often, the issue is a faulty solenoid, wiring problem, or low/dirty fluid. However, if these simpler fixes don't resolve the code, it could point to a more complex internal transmission issue.
How do I check the circuit for a low voltage condition?
You would typically use a digital multimeter to check for proper voltage (usually 12V when activated) at the solenoid's connector and check for continuity and resistance in the circuit wiring. Refer to your vehicle's specific service manual for exact values and procedures.