Blog For Technicians

Drive By Wire: Electronic Throttle Relearn

Most late model (typically after 2000) vehicles are equipped with electronic throttle (or Drive By Wire) module which eliminates the mechanical cable linkage between the accelerator pedal and the throttle body. The throttle valve or actuator module is controlled electronically by the Electronic Control Unit (ECU) to improve the safety as well as engine performance. Whenever the throttle actuator is replaced, disconnected or the battery is disconnected for a certain period of time, this electronic throttle module will either need to be recalibrated or relearned in order to keep the idle speed at a specific range. This relearn function is typically done using the proprietary OE scan tools. Two common examples are late models Nissan and Volkswagen vehicles.

In Nissan/ Infiniti vehicles, whenever the throttle actuator is replaced, the throttle actuator module needs to be relearned using the scan tool. Otherwise, the vehicle may be in limo mode and does not respond to the signal from gas pedal. With an OE scanner, this function is located under “Work Support Mode” menu of Nissan Engine Communication Software and is called “Idle Air Volume Relearn” or “Idle Air Volume Learning”. This function is used to keep the idle speed at a specific range memorized in Engine Control Unit (ECU). The following screen shows the screen shot of this function using AUTOBOSS V30 scanner:

In Volkswagen and Audi vehicle since 1997, the basic setting should be performed after the following repairs:

• Replacing the engine;
• Replacing the Engine Control Unit (ECU);
• Replacing or cleaning the throttle valve;
• Replacing the Throttle Position Sensor (TPS);
• Replacing the Transmission Control Unit (TCU);

If the throttle module basic setting is not performed, the “Check Engine Light” may come on and the vehicle may not respond to the accelerator pedal. To perform the throttle body basic setting (relearn), OE-level scan tool is required. Here are the procedures:

1. Connect the scan tool and select “Engine” control unit;

2. Select “04-Introduction to Basic Setting” as shown in figure:

3. Select the proper channel number for throttle module relearn. For 2.0L AEG and AEP engines, enter “98” as the channel number. For all other engine types, enter “60” as the channel number.

4. Once the correct channel number is entered, the vehicle will then perform the basic setting of the throttle. It typically takes about 5-10 seconds to complete. During the throttle relearn, you may hear some noise on the engine compartment;

5. The display on the scan tool should display 4 fields of data with the number on the first 3 fields. The 4th field should indicate “ADP, OK” if the basic setting is successful. If not, the 4th field on the screen will show “ADP, ERROR” to indicate the throttle relearn is not successfully completed;

6. If the throttle basic setting is not successful, go back and check if there is any Diagnostic Trouble Codes (DTCs) or loose electrical connection with the throttle module.

Can you name throttle body relearn procedures on other makes too?