Nissan/Infiniti (2000-2004) ECU

Warning! – The idle Air Control Valve MUST be replaced prior to reinstalling this ECU or immediate damage to the ECU will occur and is NOT covered under warranty

Idle Air Volume Learning is an operation to learn the idle air volume that keeps each engine within a specific range. It must be performed when the IACV-AAC valve, throttle body, or ECM is replaced

Since ECU may revert to default settings it may be necessary to pair it to your car’s immobilizer with a scan tool or dealer

Steps before the Procedure:

Before performing “Idle Air Volume Learning”, make sure that all of the following conditions are satisfied. Learning will be canceled if any of the following conditions are missed for even a moment.

• Battery voltage: More than 12.9v (At idle)
• Engine coolant temperature: 70-99°C (158-210°F)
• Transmission: A/T must be in PARK, M/T clutch must be depressed for the entire procedure
• Electric load switch: OFF (Air conditioner, headlamp, rear window defroster)

On vehicles equipped with daytime light systems, set the lighting switch to the 1^st position to light only small lamps.

• Cooling fan motor: Not operating
• Steering wheel: Neutral (Straight-ahead position)
• Vehicle speed: Stopped
• Transmission: Warmed-up (drive vehicle for 10 minutes)

Procedure:

1. Turn the ignition switch “ON” and wait at least 1 second.
2. Turn the ignition switch “OFF” and wait at least 10 seconds
3. Start the engine and warm it up to normal operating temperature
4. Check that all items listed under the topic “PRE-CONDITIONING” are in good order
5. Turn the ignition switch “OFF” and wait at least 10 seconds
6. Start the engine and let it idle for at least 30 seconds
7. Disconnect the throttle position sensor harness connector (brown), and then reconnect it within 5 seconds. (for M/T, this will require 2 people so that one can keep the clutch pedal depressed)
8. Wait 20 seconds
9. Make sure that idle speed is within specifications. If not, the result will be incomplete. In this case, find the cause of the problem by referring to the NOTE below
10. Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.

ITEM SPECIFICATION:

Idle speed M/T: 625±50 rpm (in “P” or “N” position)

Ignition timing M/T: 15°±5° BTDC A/T: 15°±5° BTDC (in “P or “N” position)

Troubleshooting

If idle air volume learning cannot be performed successfully, proceed as follows:

1. Check that the throttle valve is fully closed
2. Check PCV valve operation
3. Check that downstream of the throttle valve is free from air leakage
4. Adjust the closed throttle position switch and reset the memory
5. If any of the following conditions occur after the engine has started, eliminate the cause of the problem and perform “Idle air volume learning” all over again.

• Engine Stalls
• Erratic idle
• Blown fuses related to the IACV-AAC valve system

NOTE: It’s always better to replace the IACV with the original OEM quality Nissan/Infiniti part. If you’re still getting a P0505 code or cannot complete the relearn procedure it may also be as a result of the non-OEM Nissan/Infiniti IACV part.