Power Up After Repairs

So did you have codes or diagnostics that say do these things? ECM's rarely go bad unless there has been voltage problems, magnetic interference or moisture. If you are going ahead with this then make sure you use only Nissan original parts or you could be in for a lot of sensor misreads or unstable readings. As far as initial start-up, positive cable first then negative, start the engine and let the idle stabilize, set the brakes, turn on all accessories, lights heater fans, and put it in drive and let it the idle again stabilize, then release the brakes and drive for at least 20 minutes as you normally would, this is called drive time protocol. If the check engine light turns on during this time, then that will need to be diagnosed before proceeding with the drive time protocol.

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Hi Gene. The story behind this is I just bought this vehicle, cheap, because it needs work. The seller disclosed he was getting a P0505, IAC code. He had his mechanic replace the IAC and "fix" the ECM. On these when the IAC fails, due to internal coolant leaking into the IAC motor, the IAC motor shorts out and takes the ECM with it. I also discovered that the TPS must be replaced with the IAC and ECM. If you don't replace all three together, the new parts that you did install get fried again. For example, if you replace only the IAC, the burned out ECM will fry the new IAC. Or vice versa. Same with the TPS. With this being as critical as it sounds I just wanted to be sure if I could hook up the battery again after the repairs. The vehicle will be towed to my local Nissan Dealer for programming of the rebuilt ECM and adjustment of the new TPS. The new IAC and TPS are Hitachi OEM parts. The ECM is a freshly rebuilt numbers matching the original unit. Before I test drove the vehicle I tried to read the ECM for codes but my code reader couldn't communicate with the ECM. After the 30 minute test drive I was able to pull codes. So there's something going on with the ECM.

Maybe not, it takes at least 20 minutes drive time for the learning protocol to complete for the ECM even after it has been flashed by the dealer, have you done a live data scan yet to see if anything is out of specs with then re-flashed ECM?

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Hi Gene, I spoke with my local Nissan Dealer's service department on Friday. They advised me it's fine to hook the battery back up after I replace the IAC, ECM, and TPS. Positive first then negative. I completed the replacement of the three components. Before I reconnected the battery I checked the two ECM fuses. The 15 AMP fuse was blown. So I replaced it and connected the battery. Fuse did not blow again. Turned the ignition to the run position and, again, the fuse did not blow and the check engine light came on. So everything looks good. Also, as per Nissan, I did not try to start the engine. I'm having the vehicle towed to my local Nissan Dealer to be flashed on Tuesday. The IAC and TPS I removed from the vehicle were not OEM Hitachi parts. The TPS was loose too, screws barely finger tight. So we'll see how the flash goes. Thank you for your advice and taking the time to answer my question! I'll let you know how it goes.

Sounds like you're on your way to have it up and running. Yes I would like to know how things turn out.

My local Nissan Dealer was able to successfully flash my rebuilt ECM. I'm down to three trouble codes. Bank 2 sensor 2 heater circuit, ignition coil resistance code, and IAC code. I was advised that the guy who worked on it before me damaged the throttle body so the base idle speed can't be set. There's a stop screw on the throttle body, very much like what is found on a carburetor, that was played with, for the throttle plate. I'm replacing the bad O2 sensor this weekend and going to try to adjust that stop screw. If I understand correctly the throttle plate should be completely closed. This is so only air from the IAC passage can get past the throttle plate to allow the ECM to control the idle speed with the IAC. Jim

I cannot find any information on the minimum air rate for your vehicle. In 2001 the ECM should relearn the right idle setting after the drive time protocol after the ECM Flash. I cannot find any information on the minimum air rate for your vehicle and all the pictures and diagrams all show the throttle plate completely closed. If you have a scanner with live data, you should be able to find the TPS volts or percentage and using the set screw set it at 0, then run the protocol and it should find the correct idle. I hope the throttle body was not damaged internally when it was tampered with. Good luck.

It may get more precise as you drive it, it sounds like you did it right from what little information I could find on the vehicle as far as any throttle body adjustments. I did hear that sometimes it can take over 20 cold starts before the ECM starts running on the learned driving it has built in to it's ECM programming, so the more you drive it the better it will get. But I think your almost there.