The P0773 trouble code is a diagnostic code related to the transmission system in vehicles equipped with automatic transmissions. This code specifically indicates an electrical issue with the Shift Solenoid E circuit. When your vehicle’s onboard computer detects an abnormality in the operation or electrical signals of this solenoid, it triggers the P0773 code and usually illuminates the Check Engine Light.
| P0773 Code Meaning | P0773 Code Common Causes |
|---|---|
| Shift Solenoid E Electrical Circuit Malfunction | Low transmission fluid level |
| Transmission Control Module (TCM) detects an issue with Solenoid E | Faulty shift solenoid |
| Abnormal voltage or resistance in Solenoid E circuit | Damaged wiring or connectors |
| Improper gear ratio detected by TCM | Contaminated transmission fluid |
| Shift Solenoid E not responding to TCM commands | Defective transmission valve body |
Understanding Shift Solenoid E and Its Function
Shift Solenoid E is an integral component of modern automatic transmissions. It is responsible for controlling the flow of hydraulic fluid within the transmission, which in turn affects gear changes. When the Transmission Control Module (TCM) sends electrical signals to Shift Solenoid E, it opens or closes to direct fluid pressure to the appropriate clutch packs or bands, enabling smooth gear transitions.
Symptoms of a P0773 Code
When your vehicle triggers a P0773 code, you may experience one or more of the following symptoms:
- Illuminated Check Engine Light
- Harsh or erratic shifting
- Transmission slipping
- Delayed engagement when shifting from Park to Drive or Reverse
- Reduced fuel economy
- Vehicle entering “limp mode” with limited gear selection
Technical Explanation of P0773
The P0773 code specifically relates to an electrical issue within the Shift Solenoid E circuit. This could mean that the TCM is detecting voltage or resistance outside of the expected parameters. The problem could lie within the solenoid itself, the wiring connecting the solenoid to the TCM, or even within the TCM’s internal circuitry.
Diagnosing the P0773 Code
To properly diagnose the P0773 code, follow these steps:
- Connect an OBD-II scanner to verify the P0773 code and check for any additional transmission-related codes.
- Check the transmission fluid level and condition. Low or contaminated fluid can cause erratic solenoid operation.
- Inspect the wiring harness and connectors leading to Shift Solenoid E for any signs of damage, corrosion, or loose connections.
- Use a digital multimeter to test the resistance of Shift Solenoid E. Compare the readings to the manufacturer’s specifications.
- Check the voltage supply to Shift Solenoid E while the engine is running.
- If possible, use a scan tool with advanced transmission diagnostics to command Shift Solenoid E on and off, monitoring its operation.
- Inspect the transmission valve body for any signs of wear or damage that could affect solenoid operation.
Step-by-Step Diagnostic Procedure
- Preliminary Checks:
- Ensure the vehicle’s battery is fully charged before beginning diagnostics.
- Verify that there are no loose or corroded battery terminals.
- OBD-II Scanner Connection:
- Connect the scanner to the OBD-II port, usually located under the dashboard.
- Turn the ignition to the “On” position without starting the engine.
- Retrieve all stored codes and freeze frame data.
- Transmission Fluid Inspection:
- Park the vehicle on a level surface and warm up the engine to operating temperature.
- Locate the transmission dipstick and check the fluid level.
- Inspect the fluid for color and smell. Clean fluid should be red or pink and should not have a burnt odor.
- Wiring Harness and Connector Inspection:
- Locate the transmission wiring harness.
- Carefully inspect all visible wiring for cuts, abrasions, or signs of heat damage.
- Check all connectors for proper seating, bent pins, or corrosion.
- Solenoid Resistance Test:
- Disconnect the wiring harness from Shift Solenoid E.
- Set your multimeter to measure resistance (ohms).
- Connect the multimeter probes to the solenoid terminals.
- Compare the reading to the manufacturer’s specifications (typically between 20-30 ohms).
- Voltage Supply Test:
- Reconnect the wiring harness to Shift Solenoid E.
- Set your multimeter to measure DC voltage.
- Start the engine and let it idle.
- Backprobe the voltage supply wire at the solenoid connector.
- You should see battery voltage (around 12-14 volts) when the TCM commands the solenoid to activate.
- Advanced Scan Tool Diagnostics:
- Connect a professional-grade scan tool with transmission control capabilities.
- Access the transmission control module.
- Command Shift Solenoid E to activate and deactivate while monitoring voltage and operation.
- Valve Body Inspection:
- This step may require transmission disassembly and should be performed by a professional if you’re not experienced with transmission work.
- Remove the transmission pan and filter.
- Inspect the valve body for any visible damage or debris that could affect solenoid operation.
Solutions for P0773 Code
Based on the diagnostic results, one or more of the following solutions may be necessary:
- Replenish or replace transmission fluid:
- If the fluid level is low, add the correct type of transmission fluid to the proper level.
- If the fluid is contaminated, a complete transmission flush and fluid replacement may be necessary.
- Replace Shift Solenoid E:
- If the solenoid fails the resistance test or shows signs of failure during operation, it will need to be replaced.
- Ensure you use an OEM or high-quality aftermarket solenoid compatible with your vehicle model.
- Repair or replace wiring:
- If damaged wiring is found, repair or replace the affected sections.
- Always use proper automotive-grade wire and connections.
- Clean or replace connectors:
- Clean corroded connectors with electrical contact cleaner.
- If corrosion is severe, replace the entire connector.
- Replace the transmission valve body:
- If the valve body shows signs of wear or damage, it may need to be replaced to ensure proper solenoid operation.
- Update TCM software:
- In some cases, a software update for the Transmission Control Module may resolve electrical communication issues.
- Replace the TCM:
- If all other components check out and the issue persists, the TCM itself may be faulty and require replacement.
Cost Estimates
The cost to resolve a P0773 code can vary widely depending on the root cause and the vehicle make and model. Here are some general estimates:
- Transmission fluid change: $100 – $250
- Shift Solenoid E replacement: $200 – $500
- Wiring repair: $100 – $300
- Valve body replacement: $500 – $1000
- TCM replacement and programming: $500 – $1500
Note: These are rough estimates and actual costs may vary. Always obtain a detailed quote from a reputable repair shop before proceeding with repairs.
Warnings and Recommendations
- Driving with a P0773 code for extended periods can cause severe damage to your transmission.
- If you’re not comfortable or experienced with transmission work, it’s best to seek professional help.
- Always use the correct type of transmission fluid specified for your vehicle.
- When replacing components, use high-quality parts to ensure longevity and proper function.
- After repairs, clear the code and test drive the vehicle to ensure the issue is resolved.
Preventing Future P0773 Codes
To minimize the risk of encountering P0773 codes in the future:
- Adhere to the manufacturer’s recommended transmission service intervals.
- Regularly check transmission fluid levels and condition.
- Address any transmission-related issues promptly to prevent cascading failures.
- Avoid aggressive driving habits that can strain the transmission.
- Consider using a transmission cooler if you frequently tow heavy loads.
By following these preventive measures and addressing P0773 codes promptly, you can help ensure the longevity and smooth operation of your vehicle’s transmission system.
Frequently Asked Questions About P0773
- Can I drive my car with a P0773 code?
While you may be able to drive short distances, it’s not recommended. Continued driving can cause severe transmission damage. - How urgent is it to fix a P0773 code?
It’s quite urgent. The code indicates a transmission issue that can worsen quickly if not addressed promptly. - Will a P0773 code clear itself?
No, the code will not clear itself. It needs to be addressed and then cleared with a scan tool after repairs. - Can a P0773 code be caused by low transmission fluid?
Yes, low fluid levels can cause erratic solenoid operation, potentially triggering the P0773 code. - How long does it take to fix a P0773 code?
Repair time can vary from 1-2 hours for simple fixes like fluid replacement to several hours for more complex issues like solenoid or valve body replacement. - Is it safe to clear the P0773 code without fixing the problem?
No, clearing the code without addressing the underlying issue is not recommended and may lead to more severe transmission problems. - Can a bad battery cause a P0773 code?
While unlikely, a weak battery can cause voltage fluctuations that might trigger electrical codes, including P0773 in rare cases. - How often should I have my transmission serviced to prevent P0773 codes?
Follow your vehicle manufacturer’s recommendations, typically every 30,000 to 60,000 miles, but some vehicles may require more frequent service.