So, I got my dead alternator replaced (see thread: https://maxima.org/forums/5th-genera...ght-solid.html ).

Now I have picked up the IACV P0505 error code. I found some great info on the "Preventing ECU Failures" on this board at https://drive.google.com/file/d/1Npo...CgQHY-bE6/view

In that doc, a few things to do:

1. Put in a 7.5A fuse at ENG CONT1 so that when the IACV possibly shorts out it doesn't take your ECU with it. I did this.
2. Disconnect the electronic motor mount. Is this the connector? How do you get this connector apart?



3. Bypass the IACV coolant lines. Does this set off error codes? This car still needs to pass smog in California.

Right now, I know I will likely need a new IACV. Car has 143K on it and it is the original. I want to get these prevention items done while I wait for the IACV to arrive.

 

Regarding #3, bypassing IACV Coolant lines will not set off any check engine lights or error codes.

 

Thanks. I am ordering the new IACV from RockAuto today (OEM Hitachi ABV0039 unit). From my reading, it sounds like I need to pull the ECU and inspect it as well. Otherwise, just replacing the IACV and bypassing it could end up with the ECU (if it is damaged) damaging the new IACV.

Note: The P0505 showed up pretty much immediately after having the failed alternator replaced. I had not seen P0505 before.

For reference, with the P0505 code I have now, the behavior is:

1. Sometimes, idles normally.
2. Sometimes, if you blip the throttle, the engine will die all the way to 0 RPM's instead of settling at ~650-700 RPM's. Car will restart immediately if you try.
3. Sometimes, it starts idling erratically between 1500-2500 RPM's.

Is my ECU already damaged?

 

Couple follow-ups:

1. Given my behavior described above, does anyone from prior experience know if my ECU is damaged? Or I just have to do the work and take it out and look at it?

2. I was able to disconnect the front electronic motor mount. In this pic, which of these two goes to the rear electric motor mount?

 

Don't worry about the state of your ECU - as long as the car drives ok.
Re. the motor mount: just cut the wire, it will be ok.

 

No problem cutting them, but I was just going to try to disconnect them if I could. I got the front electric motor mount disconnected. Of the two brown connectors in the pic above, I'm not sure which one is the rear electronic motor mount. I guess I'll trace it out later this week when the replacement IACV arrives and I take off the intake parts for better access.

 

5 phillips head screws hold the IACV to the Throttle Body. 4 of them are one length (1" ?) and 1 of them is longer (2" ?) and goes all the way through the IACV to attach to the TB.

Well, I completely boogered up the 1 longer screw. Anybody know the part# for this screw? Since I am doing a coolant bypass on the IACV, do I even need to worry about putting it back?

 

So finally got my IACV replaced today. For the boogered long screw that goes through the IACV to connect to the TB, I went to Home Depot and found a #10-31 x 1.75" machine screw that works for $1.38. Sure beats the $10 the Stealer wanted for the OEM screw.

Summary:
1. I was able to disconnect both Electrical Motor Mounts without just cutting them. Quick spin around the block and didn't notice any difference.
2. I replaced the 15A with a 7.5A fuse at ENG CONT1. I've got spare 7.5A fuses in the glovebox just in case.
3. IACV coolant lines were bypassed and I just left the cooolant connection on the IACV open (nothing connected to them....no cap...etc...).

I did not pull the ECU under the dash to look for damage to any of the modules because I am being lazy. I did not have to do an idle relearn procedure. Car idles very nice now, but it also helps that it just had the alternator, idle pulley and belts recently changed as well.

Hope this helps anyone else with this issue,