Idle Air Control Valve (IACV) Replacement DIY for 2001 Pathfinder

[wmj259]

I've done the relearns probably 20 times now. But the only one I cant get done is the IACV one. When it says in the step to hold the gas pedal for 20 seconds till the SES light comes and stays on?
But the thing is I dont have any lights on at the moment. cluster is clear of lights.
It comes on and it just doesnt stop flashing. It probably stays on for 2 seconds and flashes and 2 seconds over and over again. Is that what it means?

When I did the programming on my 2001 I also never had the SES light stay on and was not sure if my training took hold or not. But it idled just fine after replacing the IACV. Also I was under the impression that the ECM would eventually train itself, but I could be wrong about that.

I have good idle also, but when I press the gas and the rpm hits 1500 it jerks to 2000 and back and forth. I don't know what is causing it, it must be a test thats not being done right or the steps I have are wrong.

[wmj259]

Could this be because the ECM is the wrong part number than what it should be?
I have a 23714 4W001 when it should be either 23710 5W511 OR 23710 6W100
based on the parts link Nissan USA eStore

[atraudes]

Wavering RPMs like that sound like a bad TPS (throttle position sensor). The FSM has a procedure for using a multimeter to verify it's working correctly. I want to say that it's recommended to replace the TPS when you replace the IACV, regardless.

[yngw13]

Hi guys....

so I went to the dealer for idle relearn just to remove the CEL light but they did so and the light came back on...it runs well...IACV is NEW (hitachi)...

Do I drive it around till it the light goes or do I get another IACV?

I have emissions by end of October and I want to get this done ASAP...

[atraudes]

Did you get the ECM repaired already? If you haven't yet, I just had mine repaired with a seller on ebay called modulerepair (listing here). It was ~$100, but closer to $200 after getting it mailed overnight each way. It arrived, I popped it in, and haven't had any problems since. If you haven't done this yet, do it before replacing anything.

Also, did they clear the codes and it came back? Just doing a relearn itself won't clear the codes, so it wouldn't be surprising to still have the light there. You can stop into pretty much any local parts store and they'll come out with a scanner and clear the code for free if you need it. Once it's been cleared and the light comes back on they can confirm whether it's indeed the P0505 code code or something else.

[cr4west]

Since a bad IACV is capable of damaging the ECM has anyone attempted to add an inline fuse to the circuit? This could be an inexpensive protection upgrade. According to the FSM we know the IACV signal voltage is 12V square wave and the resistance should be 20-24 ohms @ 68F deg. The 12V square wave signal duration varies according to temperature and I am not sure it would see 100% so if we used 80% duration, 10V would be a fair example, Ohm's law I=E/R results in .5A current. (10 Volts/20 ohms= 0.5 amp). To confirm this I am thinking of splicing in my digital multi meter into the IACV circuit to measure the voltage and currant levels while driving. I am up over 210K miles still on my original IACV so this is a real possibility of failure. A 1/2 amp inline fuse assembly should be available at most auto retail parts stores. Any thoughts?

[Buzzman]

I noticed that you list your QX4 as a 1999 model year.
If that's the case, then you are not affected by this problem.
All of the failing IACV's that are talked about on this forum are on 2001 and newer models, with the 3.5 engine.
I have not heard of this problem on the 3.3 engine.

[cr4west]

Looks like I do not need to worry about it due mine being a 3.3 engine. For the benefit of the 3.5 owners I researched the data sheet on chip part number STA509A located at IC17 on the ECM/ECU board. Maximum current rating was 6 amps. So that gives us our fuse rating range somewhere between 1 to 5 amps.

[rgk]

A bit off topic here, but since this thread is the current one at the top of the board regarding the 3.5 IACV mess:

I was just hit by a bad IACV, which fried my ECU. When I removed my upper intake plenum to remove the old IACV, I noticed a bit of coolant had splashed out of the plenum. Looking at the coolant housing within the IACV, I noticed that a leak would allow coolant to directly enter the IACV motor. This made me wonder whether it wasn't coolant, in fact, that was causing these shorts and frying the ECU.

I have heard of people replacing their IACVs, only to have them fail a few months down the road. I have to wonder whether these people replaced their IACV but not the gasket, which is housed on the plenum side of the intake (not the actual IACV).

I also have to wonder whether drivers can avoid these IACV issues by simply replacing their gaskets before they start leaking.

Just my .02. Thoughts?

[Legend11]

I received the "OEM" IACV today, installed it, and my Pathfinder now idles just perfect. Before installing I confirmed the resistance between the control pins was in spec.

My new Nissan OEM and failed Hitachi ABV0043 IACVs appear to be exactly the same, and are likely produced on the same equipment. Even the smallest markings and mold seam lines match. The only differences I found are:
- One ID stamped is different, my guess is it indicates a different production run ID
- the Hitachi has a ABV0043 sticker, the OEM does not
- The OEM comes in a NISSAN Genuine Parts box, the Hitachi comes in a Hitachi box
- The OEM is $150-$300 depending on your source, the Hitachi is around $90

I suggest anyone having idle problems, and especially a P0505 code should follow the P0505 diagnosis guidelines in the "EC" manual (http://www.nicoclub.com/archives/nissan ... nuals.html) including testing the resistance on your IACV with an ohmmeter. If the resistance is below spec you should consider parking your Pathfinder pending IACV replacement or run the risk of damaging the ECM.

New OEM labeled IACV on top, failed Hitachi labeled OEM on bottom:

There is temptation with the $90 price, but the concern I have is your Hitachi IACV only had 3,000 miles on it prior to it failing. This is steering me towards going with the OEM part which I'm assuming you haven't had any issues with since. I'm seeing the OEM parts around $230 shipped