u1000 error code

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unreal2k1
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Joined: Mon Aug 19, 2013 10:37 am

Postby unreal2k1 » Tue Jan 16, 2018 12:31 pm

I know I am bumping an old thread here but this u1000 code is an overheating trans and I had this issue with the bypass and a cooler that was installed by a shop that was garbage and only lasted a year. They also did not tie in the factory cooler so after a about 2k in parts from a new cluster to solenoid pack in the trans it was just an overheating trans that was doing this and going into Limp mode. So yeah towing could have done it for the OP and also doing some off road. Just sharing my 2 cents on this.


Lit
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Joined: Thu Mar 20, 2014 2:52 pm
Location: Farmington, UT

Postby Lit » Thu Feb 22, 2018 11:56 am

I agree with real2k1. I had the same problem due to the trans fluid radiator bypass that would cause my 2008 Frontier to throw that code, limp mode, when towing in 4Lo. Note, the V6 Pathfinder and Frontier have the same 4.0 engine, radiator and trans.

Every time when I would tow my 3800lbs camp trailer to a certain camp spot that required about 1/2 mile in 4Lo, the trans would go into limp mode and I would get the U1000 code. I would be able to make it the last short distance by turning off the truck for a couple of minutes and then restarting it. The next morning it would have cooled down and I could not reproduce the problem. The tow home was all downhill, so I the problem would not come back until next time I was towing to that camping spot. I did not have a Trans temp gauge on the Frontier, so one time I brought my IR temp gun to check the Trans pan temp when it went into limp mode and it was at 245 degrees. I do realize that was not really an accurate test of the temperature of the trans fluid, as the engine, exhaust and catalytic converters would likely effect that temp, but either way, I think it was way too high.

I only did the bypass to prevent the SMOD problem. So I ended up undoing the bypass and replacing my radiator and the problem has not returned.

Aerodan
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Joined: Wed Apr 13, 2016 5:37 pm

Overheating trans

Postby Aerodan » Tue Feb 05, 2019 8:38 pm

Just adding my experience with my 2006 SE.

I've had mine throw U1000 and lose power many times. One time I was towing, all other times I was driving slowly up more than 4000' vertical feet going up mountain passes. I've had it happen in 4WD and 2WD. I can repeat it on the same road if I drive slow, but I can prevent it from happening if I drive faster (pulling 40-50 around winding turns). The first time it happened I popped the hood and saw smoke coming from the transmission. Every time it happens, if I pop the hood and let the vehicle cool for an hour or so, the vehicle drives normal. I've done the tranny radiator bypass.

I've concluded my issue is the granny overheating when under prolonged load driving uphill slowly.

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palmerwmd
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Postby palmerwmd » Wed Feb 06, 2019 4:33 pm

The bypass does rob the system of cooling capacity.
Be glad your tranny went into limp home home otherwise it might be severly damaged.

The best practices solution for avert the SMOD problem is a new radiator (and restore factory ATF plumbing)
This goes double for anyone who tows.


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