av8shunmeckanec

Just like the title says: I have a "service engine soon" with no gear indicator and severe loss of power. I erased the code and it was gone for a couple of days. Today I drove the P** out of it up HWY 2 and the light came back again. Manual mode wont work and there is a significant loss of power. It acts like an old lady driving a Cadillac on Sunday morning until you get to about 60mph. And that is with the pedal to metal.

Like the title says, I have code U1000 and I have done some research on google and here but there is no good direction to start looking. Battery neg cable is tight and so is the ground point adjacent to it.

I did replace the radiator and thermostat as posted here . It may or may not have something to do with it.

As a mechanic I try to stick to KISS (keep it simple stupid) but I have no clue why changing the radiator and/or thermostat would induce a problem like this.

Maybe it's just a coincidence.

Any help is appreciated. Thanks,

DavesZ#3

iTrader: (26)

U1000 typically indicates a problem with the CAN communications. Did you search here and read this post?

https://my350z.com/forum/maintenance...-bulletin.html

BTW - a lot of posts related to U1000 seem to be ECU ground related, not grounding in general.

av8shunmeckanec

I already read that post Dave.

My understanding with the 350z along with my FX35 is that some components reports to a computer that communicates along a databus.

From my discrepancy it seems that the databus that reports info for the (at minimum, Gear Indication) is not reporting properly. This is probably due to a bad ground to a particular computer.

I was hoping that somebody could give a more direct answer to which ground is related to that computer.

I dont want to search all of the grounds on the car and/or re-seat every connection.

Hopefully my description will point to a component that has to do with the transmission gear indicator and the loss of power.

Thanks for the quick replies,

av8shunmeckanec

I erased the code and the check engine light went out.

On the way to work today I noticed that the transmission isnt going into 5th gear and it wont go into "manual mode". The indicator remains on D when in manual mode and it doesnt shift. It stays in auto mode. I havent gotten the check engine light again. The code reader showed code U1000 and a pending code U1000. Not sure if there is a difference.

av8shunmeckanec

Neither code comes up right away after resetting it but now the only code I keep getting P0720. The code scanner website says its the vehicle speed sensor. I'm going to re-seat the connector on the speed sensor and/or check it out.

Lemme know if anybody has some other ideas.

Rburris1

Cavemanz33

OP hasn't logged in to this site since 2012, it looks like. You have same issues with speed? Any DTCs?

Atreyu'z 350

https://www.autocodes.com/u1000_nissan.html

av8shunmeckanec

Sorry for not replying back. I havent had the Z for a few years now but thought it would be beneficial to know the result. Dont remember why, but i replaced the radiator with a Mishimoto unit that doesnt have the trans cooler in it. Therefore I bipassed the trans cooler. Stupid mistake. The tranny was overheating and I suppose it was going into a 'limp home mode'. The fix was a strap on trans cooler.

To those with the same problem but original radiator, I suggest checking trans cooler blockage or a problem with the trans temp sensor.

rkromero13