The following learning procedures will allow your ECU to re-learn important sensor data. This data can be lost if the ECU has been reset or if the vehicle has been inactive for extended periods of time with a dead battery. All of the following procedures are fairly time sensitive and any discrepancies in timing can produce a DTC and the SERVICE ENGINE SOON lamp will illuminate. It is recommended that you perform the following procedures using an accurate counting method (one one-thousand, two one-thousand, etc..) if a timer or stopwatch is inaccessible.
It is recommended that the procedures be completed in the following order. If an error occurs, you should reset the ECU and start the following procedures over. The following procedures can be completed on most (but not all) R50 and R51 models. Completion of any of the following procedures on a vehicle which does not warrant it will not produce any DTC's or damage the vehicle.
Please read all steps before beginning any procedure.
________________________________________________________ACCELERATOR PEDAL RELEASED POSITION LEARNING (2003 - 2004 Pathfinders + QX4's)"]________________________________________________________
Description:
“Accelerator Pedal Released Position Learning” is an operation to learn the fully released position of the accelerator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed each time harness connector of accelerator pedal position sensor or ECM is disconnected.
Procedure:
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch “ON” (without starting vehicle) and wait at least 2 seconds.
3. Turn ignition switch “OFF” wait at least 10 seconds.
4. Turn ignition switch “ON” (without starting vehicle) and wait at least 2 seconds.
5. Turn ignition switch “OFF” wait at least 10 seconds.
________________________________________________________THROTTLE VALVE CLOSED POSITION LEARNING (2003 - 2004 Pathfinders / QX4's)"]________________________________________________________
Description:
“Throttle Valve Closed Position Learning” is an operation to learn the fully closed position of the throttle valve by monitorizing the throttle position sensor output signal. It must be performed each time harness connector of electric throttle control actuator or ECM is disconnected.
Procedure:
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch “ON” (without starting vehicle).
3. Turn ignition switch “OFF” wait at least 10 seconds.
Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.
________________________________________________________IDLE AIR VOLUME LEARNING (2003 - 2004 Pathfinders / QX4's)"]________________________________________________________
Description:
“Idle Air Volume Learning” is an operation to learn the idle air volume that keeps each engine within the specific range. It must be performed under any of the following conditions:- Each time electric throttle control actuator or ECM is replaced. - Idle speed or ignition timing is out of specification.
Preparation:
Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied. Learning will be cancelled if any of the following conditions are missed for even a moment.
- Battery voltage: More than 12.9V (At idle) - Engine coolant temperature: 70 - 100°C (158 - 212°F)- PNP switch: ON- Electric load switch: OFF (Air conditioner, headlamp, rear window defogger)On vehicles equipped with daytime light systems, set lighting switch to the 1st position to light only small lamps.- Steering wheel: Neutral (Straight-ahead position)
Procedure:
1. Start engine and warm it up to normal operating temperature.
2. Check that all items listed under the topic “Preparation” (previously mentioned) are in good order.
3. Turn ignition switch “OFF” and wait at least 10 seconds.
4. Confirm that accelerator pedal is fully released, turn ignition switch “ON” (without starting vehicle) and wait 3 seconds.
5. Repeat the following procedure (5-a and 5-b) quickly five times within 5 seconds.
5-a. Fully depress the accelerator pedal.
5-b. Fully release the accelerator pedal.
6. Wait 7 seconds, fully depress the accelerator pedal and keep it for approximately 20 seconds until SERVICE ENGINE SOON stops blinking and turns ON.
7. Fully release the accelerator pedal within 3 seconds after SERVICE ENGINE SOON turned ON.
8. Start engine and let it idle.
9. Wait 20 seconds.
(Timing diagram)
10. Rev up the engine two or three times and make sure that idle speed and ignition timing are within the specifications.
(The above specifications apply to R50 model ONLY; R51 model has different specifications)
11. If idle speed and ignition timing are not within the above specification, “Idle Air Volume Learning” will not be carried out successfully. In this case, find the cause of the incident by referring to the “Diagnostic Procedure” below.
Diagnostic Procedure: (Perform only if Idle Air Volume Learning was unsuccessful)
1. Check that throttle valve is fully closed.
2. Check PCV valve operation.
3. Check that downstream of throttle valve is free from air leakage.
4. When the above three items check out OK, engine component parts and their installation condition are questionable. Check and eliminate the cause of the incident.
5. If any of the following conditions occur after the engine has started, eliminate the cause of the incident and perform “Idle air volume learning” all over again:
− Engine stalls.
− Erroneous idle.
Good Luck!
