Start with the basics. Make sure the battery connections are clean and tight.
I check all the fuses, replaced all the relays that were ignition, ecu, or starter related. Also put in a Ipdm box.Something going on with the fuse box?
I replaced the ends on the 2 grounds going to the fender well. I didn't know where they went. Thanks for pointing out they go to ipdm and ecu. I haven't messed with the bcm but I will look at it. I checked all fuses again tonight.Check for power on each of the battery fuses on the positive post. Maybe one of the replacements popped.
Disconnect and reconnect every connection on the ipdm, the ecu, and the bcm. The bcm is located above the drivers right foot. Disconnect one of the battery terminals before you start pulling connectors.
Also there are 2 grounds on the fender, next to the positive battery post. Those ground the ipdm and the ecm. It might be worth pulling the battery and getting at those, loosen and retighten, or remove and clean them up if needed. Also be sure the battery-to-chassis ground is tight.
I couldn't get the active auto test to work. I also agree that every thread I have read with the fan running does seem to lead to ecu. Does anyone have recommendations on where to buy a new ecu?Only time I have heard of the fan starting to run as soon as the key is on - the ECU was bad. Not trying to scare you, but thats what I have seen here and another Nissan board..
Pull codes? If your meter won't connect then it could be a bad ECU (or the ECU isn't getting power). If you can connect and it gives you a U1000 or similar, it might not be connecting to the BCM. Could be wiring or bad BCM.
I would also try the active auto test. Doesn't rule out the IPDM, but it might shed some light on things - especially if everything there works.
If the active auto test doesn't work - that points more towards the IPDM?I couldn't get the active auto test to work. I also agree that every thread I have read with the fan running does seem to lead to ecu. Does anyone have recommendations on where to buy a new ecu?
No I'm sure I didn't reverse the cables. I've learned from that mistake decades ago lol. I will look at those 2 fuses again but have replaced both just for sanity. Thanks for input.Be sure to check fuse #1 in the fuse junction block, next to the glove box. That provides power to parts of the ecm and ipdm.
Also check fuse #53 in the ipdm.
Less likely but while you are at it, there are grounds just forward of the air intake where it passes through the left fender. Clean those up as needed.
On the initial jump start when this problem arose, any chance you reversed the jumper cables, even for a second?
Thanks for the input. I believe the ecu is the culprit but wanted input before spending anymore time and MONEY on this.Hey just wanted to weigh in, i had the exact same issue a few years ago and a new ECU was indeed the fix. Nissan diagnosed it, but sure enough a new ECU fired it right up.
Looking back, since i didn't need to drive the vehicle daily i would have sent the ECU out to be repaired vs buying a $1200 new one. I haven't used Flagship but directed an international X owner there and never heard back on the end result. I also assume that the repair process avoids the headache of flashing ECU's at the dealer and security system/vehicle key crap.
Solid elimination suggestions in this thread by the way. please report back with resolution.