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I've got a '03 LE RWD and for a while now it's been having a problem that's been causing the car to severely lacking power (accelerating at less than 1/4 of normal speed even with pedal to the floor) and to also "grab" or "jerk" when decelerating as if it is having trouble downshifting, it is a hard symptom to describe but it isn't a prolonged or aggressive "jerk" but it will happen at any speed so long as you are not on the gas pedal, all of these problems occurred at the same time which is why I believe they both have the same cause. I went ahead and scanned it to see if that would give me an answer as it does not seem particularly like mechanical failure, however the only code I could pull (which isn't really a helpful one) was a "U1001(Invalid or Missing Data for Primary ID)" Which I'm guessing means that for some reason the car can't communicate with the OBDII scanner or that there is a miscommunication/misconnection within the CANBUS itself. I am completely stumped here as I have yet to come across (online or IRL) across another Pathy with the same problem (probably also because it is such a rare symptom to describe without driving the car for yourself. I'll also mention that a friend of kine suggested that it could be a torque converter issue which I doubt simply because i've never been in a car with a malfunctioning torque converter that behaved that way, and because a torque converter shouldn't cause that drastic of a power loss but hey I could be wrong, another note is that the car has been babied it's entire life(150k mi) and maintained relatively well. If anyone could help me out and point me in the right direction and any advice it would be greatly appreciated.

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  • 3 weeks later...

Nissan has a service bulletin on this (though it's listed for 2005+). It assumes you have their special service tools, but I'll bet you could do the electrical checks they show without their fancy breakout box if you've got a multimeter and steady hands.  This source suggests checking ground points in the engine bay and under the dash.

The service manual should have diagrams of where modules are, where the CAN wires are run, and where the ground points are. Like the bulletin, the later manuals spend a lot of time walking you through how to press buttons on tools you don't have, but there should still be some usable information in there.


Good luck!

Edited by Slartibartfast
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  • 2 months later...

My 2001 4x4 auto has this or a similar issue. 

around 45mph and above, if there is a slight downhill (where no throttle is needed to hold speed) or any type of downhill, releasing the accelerator induces this "rocking" feeling. It's subtle but it's like its smoothly transitioning from engine braking to coasting about 1 transition per second. It varies the load on the engine as the tach fluctuates up and down as much as 500 rpm per transition. This can be induced at lower speeds than 45mph on the same downhill by turning off overdrive. However, 1st gear and 2nd gear speeds don't appear to have this issue as I can coast hilly and flat neighborhoods without this issue occurring. This issue is not intermittent.


Additionally, at speeds above 45 mph, the sudden jolt can occasionally happen. It happens so fast it's hard to interpret what happens. It happens in the blink of the eye. Either the engine does a extremely quick stutter or something in the drivetrain releases or something brakes/binds up. Its accompanied with a thump or thud sound which could be the transmission, rear end backlash or u-joint backlash. This is more likely to occur at faster speeds. It usually happens at stable throttle inputs (not actively accelerating or decelerating) but can happen once in a while at moderate accel or decel scenarios. I have yet to find a way to reproduce this and seems entirely random and doesn't happen every time I drive above 45mph.


Previous owner said the transmission was repaired at one point, but didn't divulge any other details.

I suspect there could be electrical issues as the headlights dim in with the rhythm of the turn signal when they are in use (this does not happen on my 02). Also, it sat in a field for 6 months before I bought it and discovered wire loom chewed by a rodent. Also, I had accidentally touched terminals with a backward battery (ford battery with opposite poles) the day after i bought it.

Lastly, it may have a partially clogged cats which may affect vacuum readings. 


Perhaps someone else has a similar issue we can find a common condition with.


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