ECM and IACV issues

[FMHQX4]

Hi guys, new forum member here. I've just purchased a 2003 qx4 with some known issues. I've been browsing around quite a bit and have found many helpful things, but now I need some further help.

I bought the car from my aunt, she explained that the dealer replaced the IACV and that the TPS and ECM would also need to be replaced. I replaced the TPS, took it for a second opinion at a different dealer (who confirmed IACV had been replaced and ECM was bad) and then I sent out the ECM to Circuit Board Medics for it to be repaired.

I just got the ECM back, plugged it in and started it up. Before I can start the learning procedure the car stalls out. It looks and smells like some smoke may have billowed up from the dash. It won't start again, and just keeps turning over. After some further inspection I find the 10A fuse under the hood labeled ECCS2 has blown. I replace it and it starts again, but then again blows immediately. If I disconnect the IACV connector the fuse doesn't blow.

Has the new IACV gone bad and possibly fried the ECM again? Where do I go from here? Can someone recommend some further diagnosing with out throwing a bunch more money at this?

Also, it's now throwing a p1610 code, which is saying it's in lock mode. But that may have something to do with the blown fuse?

Thanks,
-Kyle

[centralcoaster33]

Hi welcome to NICO Club!

Sorry about your issues. To have the new computer blow your ECCS2 fuse over and over, I'd be sending it back to metrics under warranty or at least give them a call and discuss it a bit. Perhaps your pins didn't seat properly when plugging it back in, I'm not sure. ECCS is just Nissans name for ECU, so it's power to the computer that's getting tossed. You can check your ECCS relays and see if those are shorted I suppose. You can check the wires to your IACV, test for continuity, voltage, ground and shorting. You can run without IACV a while to try and get more codes out of the computer maybe.

Also, there is the FSM and that will have a lot explained. Check there to really get into it if you like. Please keep us updated. EC chapter has the error codes. p1610 will point you to the el chapter for the lock security issues, but look to the first issue with ECU power i think because they could be related. There is a ground at F20 and F25 that should be checked.

http://www.nicoclub.com/FSM/QX4/2003/

[FMHQX4]

Thanks for the reply, good info! I’ll hopefully have some time to dig a little further this weekend.

[sroberts]

Check your IACV resistance with an ohm meter. I've replaced my IACV twice. The first time caused the "catastrophic failure", taking out the ECM. Circuit Board Medics repaired it. Then within a year, and probably only a few thousand miles, the truck started stalling at idle. Paranoid about another ECM failure, I took out the IACV electrical component and used an ohm meter to test the resistances per the manual. Sure enough one measurement was out of spec, with a much lower resistance - a short. Fortunately it did not fully short and blow the ECM again.

[sroberts]

If you find you need to replace the IACV, go with the Hitachi part and don't waste your money on the Nissan OEM part. They're the same. I ordered Hitachi the first time and Nissan OEM the second, gamb|ing that by paying extra I would avoid a repeat failure. It was a fools bet and I received the exact same item. Above is OEM, below is the short-lived twin.

[centralcoaster33]

Seems like adding an inline fuse could prevent further shorts frying the ecu... if you're smart with electronics... I'm not.

[FMHQX4]

I sent my ECM back to circuit board medics and they confirmed the board had failed again because of the IACV. They fixed it under warranty at no cost (great people they are!).

If you find you need to replace the IACV, go with the Hitachi part and don't waste your money on the Nissan OEM part. They're the same. I ordered Hitachi the first time and Nissan OEM the second, gamb|ing that by paying extra I would avoid a repeat failure. It was a fools bet and I received the exact same item. Above is OEM, below is the short-lived twin.

Thanks, sroberts for the info. I just ordered the Hitachi part.

Seems like adding an inline fuse could prevent further shorts frying the ecu... if you're smart with electronics... I'm not.

I was thinking about doing something like this. Has anyone else done this before? Would love some info on this if you have.

[QCtech]

Just to make clear. I dont know why your car being a 2003 burned the ECM. The IACV problem that burned the ECM is with the 2001-2002. Completely different IACV. The 2003 one does not burn the ECU and is a physically different unit. The 2003 is completely electrical. So I would say that the company you sent it initially did something wrong and they are blaming the IACV for it.

[FMHQX4]

I'm thinking mine must have been built early 2003 or late 2002, because mine does in fact have the same IACV as the one pictured above. It also is throttle by cable rather than throttle by wire. I bought a junkyard ECM before I pulled the old one only to later realize it was not the same at all.

[AlanAZ]

I dont know why your car being a 2003 burned the ECM. The IACV problem that burned the ECM is with the 2001-2002. Completely different IACV. The 2003 one does not burn the ECU and is a physically different unit. The 2003 is completely electrical.

True if his vehicle was a Pathfinder, but the 2003 QX4, disappointingly, uses the 2002 throttle body and IACV.

[wmharristn]

My 2003 QX4 has the same IACV issue and has blown the computer. I would like to send it to Circuit Board Medics for repair but I don't know where the ECM is located. Since Nissan shut down the service manual section of this forum, I don't have any reference to locate the ECM. Can someone describe where it is located in the car? Is it difficult to access?

[04pathse]

https://www.youtube.com/watch?v=YnnLuXIJu-g&t=46s

[Legend11]

If you find you need to replace the IACV, go with the Hitachi part and don't waste your money on the Nissan OEM part. They're the same. I ordered Hitachi the first time and Nissan OEM the second, gamb|ing that by paying extra I would avoid a repeat failure. It was a fools bet and I received the exact same item. Above is OEM, below is the short-lived twin.

Since the Hitachi part was short-lived, wouldn't this prove the quality to be less than OEM? I'm going to sleep on on it before I make the decision. Thanks for any info