Instruction Manual for Dorman 977-300 Throttle Body Assembly

1. Introduction

This manual provides essential information for the installation, operation, and maintenance of your Dorman 977-300 Throttle Body Assembly. This 100% new electronic throttle body is designed to match original equipment for fit and performance, featuring a corrosion-resistant aluminum body, new sensor, and circuit board for reliable operation. It incorporates an upgraded design with a proprietary Sensor Shield butterfly shaft seal to prevent future failures, ensuring a durable and reliable replacement for your vehicle.

2. Product Overview

The Dorman 977-300 Throttle Body Assembly is a critical component in your vehicle's fuel system, controlling the amount of air entering the engine. Its robust construction and advanced features ensure optimal engine performance and longevity.

Figure 2.1: Main view of the Dorman 977-300 Throttle Body Assembly, showcasing its aluminum body and electronic components.

Figure 2.2: Front view of the throttle body, highlighting the air intake opening.

Figure 2.3: Back view of the throttle body, showing the mounting points.

Figure 2.4: Top view of the throttle body, illustrating the overall design.

Key Features:

• Upgraded Design: Features a proprietary Sensor Shield butterfly shaft seal to prevent future failures.
• New Construction: 100% new case aluminum, not remanufactured, for enhanced reliability and no core charge.
• Rigorously Tested: Complies with Federal Motor Vehicle Safety Standards (FMVSS) and endurance-proven with over 1 million cycle tests.
• Trustworthy Quality: Vehicle try-on tested, and backed by a team of product experts in the United States and more than a century of automotive experience.

3. Compatibility

The Dorman 977-300 Throttle Body Assembly is compatible with select Ford, Lincoln, and Mercury models. Please confirm fitment for your specific vehicle trim using a vehicle compatibility tool before installation.

Compatible Vehicles:

• Ford C-Max: 2013, 2014, 2015, 2016, 2017, 2018
• Ford Escape: 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020
• Ford Fusion: 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020
• Ford Ranger: 2013, 2014, 2015, 2016
• Ford Transit Connect: 2014, 2015, 2016, 2017, 2018, 2019, 2020
• Lincoln MKZ: 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020
• Mercury Mariner: 2009, 2010, 2011
• Mercury Milan: 2010, 2011

4. Installation and Setup

Proper installation is crucial for the optimal performance of your new throttle body. It is recommended that installation be performed by a qualified automotive technician. Always refer to your vehicle's specific service manual for detailed, step-by-step instructions.

General Installation Steps:

1. Disconnect Battery: Before beginning any work, disconnect the vehicle's negative battery terminal to prevent electrical hazards. It is often recommended to touch the disconnected positive and negative battery cables together for about 20 seconds to clear the vehicle's computer memory.
2. Access Throttle Body: Locate and carefully remove the air intake ducting and any other components obstructing access to the existing throttle body.
3. Remove Old Throttle Body: Disconnect the electrical connector and remove the mounting bolts securing the old throttle body. Carefully detach it from the intake manifold.
4. Install New Throttle Body: Ensure the mounting surface is clean. Position the new Dorman 977-300 Throttle Body Assembly, ensuring the gasket (typically included with the new part) is correctly seated. Secure it with the mounting bolts, tightening to the manufacturer's specified torque.
5. Reconnect Components: Reattach the electrical connector to the new throttle body. Reinstall the air intake ducting and any other components that were removed.
6. Reconnect Battery: Reconnect the negative battery terminal.
7. Computer Relearn: After installation, the vehicle's engine control unit (ECU) may need to 'relearn' the new throttle body's parameters. This process can vary by vehicle and may involve simply starting the engine and allowing it to idle, or it might require a specific drive cycle or diagnostic tool. Consult your vehicle's service manual for the exact procedure.

5. Operation

The Dorman 977-300 Throttle Body Assembly functions as a precise air control valve for your engine. When you press the accelerator pedal, the electronic throttle body opens, allowing more air into the engine. The vehicle's ECU then adjusts fuel delivery accordingly to maintain the optimal air-fuel mixture for efficient combustion and power output. This electronic control ensures smooth and responsive acceleration, as well as improved fuel economy.

6. Maintenance

While the Dorman 977-300 Throttle Body is designed for durability and features a Sensor Shield to protect internal electronics from contaminants, periodic inspection is beneficial. It is generally not recommended to manually clean modern electronic throttle bodies with harsh chemicals, as this can damage sensitive internal components or coatings. If cleaning is deemed necessary, use only throttle body specific cleaner and follow vehicle manufacturer guidelines. Regular vehicle maintenance, including air filter replacement, helps ensure clean air reaches the throttle body, contributing to its long-term performance.

7. Troubleshooting

If you experience issues after installing or while using the Dorman 977-300 Throttle Body Assembly, consider the following common symptoms and potential solutions. Always consult a qualified technician for diagnosis and repair if you are unsure.

Common Symptoms of Throttle Body Issues:

• Rough Engine Running or Idling: The engine may feel shaky or unstable, especially at idle.
• Loss of Engine Power or Limp Mode: The vehicle may suddenly lose power, accelerate slowly, or enter a 'limp home' mode where speed is severely restricted.
• Check Engine Light (CEL) or Yellow Wrench Icon: These warning lights on your dashboard indicate a detected fault in the engine or powertrain system.
• Diagnostic Trouble Codes (DTCs): Common codes related to throttle body issues include P2111 (Throttle Actuator Control System - Stuck Open) and P2112 (Throttle Actuator Control System - Stuck Closed).
• Poor Shifting: In some cases, a faulty throttle body can affect transmission shifting behavior.

Troubleshooting Steps:

1. Check Connections: Ensure all electrical connectors to the throttle body are securely attached and free from corrosion.
2. Inspect Air Intake: Verify that the air intake system is free of leaks, cracks, or obstructions.
3. Computer Relearn: Confirm that the vehicle's ECU has properly adapted to the new throttle body. If not, perform the relearn procedure as outlined in your vehicle's service manual.
4. Professional Diagnosis: If symptoms persist, it is highly recommended to have the vehicle diagnosed by a professional technician using specialized diagnostic equipment.

8. Specifications

9. Warranty and Support

Dorman stands behind its products with over a century of automotive experience, providing reliable solutions for vehicle repair and maintenance. For specific warranty details, technical support, or to explore other Dorman products, please visit the official Dorman website or contact their customer service directly.

You can find more information and products at the Dorman Store.