How to Perform a Throttle Relearn on JAC Vehicles
If your JAC vehicle is experiencing issues like rough idling, stalling, or poor throttle response, it may be time to perform a throttle relearn procedure. A throttle relearn, also known as a throttle adaptation or throttle position sensor (TPS) relearn, recalibrates the vehicle’s electronic throttle control system. This allows the engine control module (ECM) to relearn the correct throttle position sensor voltages for optimal throttle response and idle quality.
In this comprehensive guide, we will walk through the throttle relearn process for JAC vehicles step-by-step. We’ll also discuss what models this applies to, the symptoms that indicate a relearn is needed, and tips for success. By the end, you’ll have all the knowledge needed to perform a throttle relearn on your JAC with confidence.
What is a Throttle Relearn?
Modern vehicles like JACs use an electronic throttle control system, also known as drive-by-wire. Instead of a physical cable connecting the accelerator pedal to the throttle body, the throttle is controlled electronically via the engine control module (ECM). The throttle position sensor (TPS) measures throttle angle and sends a voltage signal to the ECM indicating the throttle’s position.
Over time, the TPS can become uncalibrated due to factors like battery disconnection, ECM memory loss, or throttle body cleaning/replacement. When this happens, the ECM may not know the correct closed and open throttle voltages. This can cause symptoms like a rough idle, stalling, hesitation, and poor throttle response. A throttle relearn procedure recalibrates the TPS so the ECM relearns the correct throttle voltages.
Symptoms Indicating a Throttle Relearn is Needed
If you notice one or more of the following symptoms with your JAC vehicle, it may be time for a throttle relearn:
- Rough, unstable, or high idle
- Engine stalling
- Hesitation or stumble upon acceleration
- Surging or uneven power delivery
- Check engine light on with throttle-related fault code
- Unresponsive or “touchy” throttle pedal
A throttle relearn is often needed after:
- Battery died or was disconnected
- ECM/PCM was reset or lost memory
- Throttle body was cleaned or replaced
- Mass airflow sensor was cleaned or replaced
- Accelerator pedal was replaced
JAC Models Requiring a Throttle Relearn Procedure
The throttle relearn procedure applies to the following JAC models equipped with electronic throttle control:
- JAC J3 (2008-2014)
- JAC J5 (2011-present)
- JAC J6 (2014-present)
- JAC iEV5 (2014-present)
- JAC iEV6E (2016-present)
- JAC iEV7 (2017-present)
- JAC Refine S2 Mini (2015-present)
- JAC Refine S3 (2017-present)
- JAC Refine S5 (2013-present)
- JAC Refine S7 (2017-present)
Consult your owner’s manual or a JAC dealer to confirm if your specific model year requires a throttle relearn after battery disconnection or throttle body service. Some newer JAC models may perform an automatic throttle relearn on their own.
Tools & Supplies Needed
To perform a throttle relearn on your JAC, you will need:
- A safe, level work area
- Your vehicle’s owner’s manual
- A code scanner to check and clear fault codes (optional but recommended)
- A helper to assist in some of the steps (optional but helpful)
Step-by-Step Throttle Relearn Procedure
Follow these steps to perform a throttle relearn on your JAC vehicle:
- Park your vehicle on a level surface and set the parking brake.
- Turn off all electrical accessories including the radio, A/C, lights, wipers, etc.
- Make sure the battery is fully charged. Check the voltage with a multimeter. It should be over 12.6 volts.
- Disconnect both battery terminals and touch the cable ends together for 30 seconds to drain any residual power from the system. This ensures a clean ECM memory reset.
- Reconnect the battery terminals, making sure they are tight and free of corrosion.
- Insert your key and turn the ignition on (but do not start the engine yet). Wait at least 1 minute for the system to initialize.
- Start the engine and let it idle in park for at least 3 minutes. Do not press the accelerator pedal during this time.
- After 3 minutes, turn off the engine and remove the key. Wait at least 1 minute.
- Restart the engine and let it idle again for 3 minutes without touching the accelerator. The engine may run rough or fast at first but should gradually stabilize.
- After 3 minutes, rev the engine lightly a few times, then drive the vehicle around the block. Drive smoothly, accelerating gradually. Avoid full throttle.
- Return and park the vehicle. The throttle relearn process is complete. The ECM should now be recalibrated.
- If you have a code scanner, connect it and clear any throttle-related fault codes that may be stored. Drive the vehicle for at least 10 miles to allow the ECM to fully relearn.
Tips for a Successful Throttle Relearn
Here are some important tips to ensure a successful throttle relearn on your JAC:
- Always disconnect the battery before servicing the throttle body or sensors to avoid setting fault codes.
- Make sure the battery is fully charged before beginning the relearn process. A low battery can cause inaccurate TPS readings.
- Do not touch the accelerator pedal during the relearn process until instructed to do so. Let the engine idle on its own.
- Be patient and give the ECM time to relearn during the idling phases. Don’t rush through the steps.
- If the engine is stalling or idling very roughly during the relearn, there may be an underlying issue with the throttle body, TPS, or idle air control valve. Consult a professional.
- Avoid disconnecting the battery in the future unless absolutely necessary. Repeated battery disconnections can confuse the ECM.
- If you continue to have throttle-related issues after the relearn procedure, there may be a deeper problem. Have the vehicle scanned for fault codes and consult a JAC dealer or qualified mechanic for further diagnosis.
Final Words from Boss Erwin
A throttle relearn is a straightforward procedure that can often resolve common throttle-related issues on JAC vehicles like rough idle, stalling, and poor acceleration. By following the step-by-step instructions and tips outlined in this guide, you can recalibrate your JAC’s electronic throttle control system and restore optimal performance.