Error Code P2123 Anyone have experience with this one?

[ferrariowner123]

Hello All! 

 

My 03 keeps trowing error codes like its at a ball toss game at the carnival. The latest one is code P2123 "Throttle/ Pedal Position sensor/ switch D circuit high.

 

I cant seem to find much info on this one for the pathfinder specifically. That being said, i did have some success with the maxima forums. From what i can gather, its almost the same symptoms (slip, VDC off lights come on) with the exception being that on the pathy the 4WD light come on. I have maybe 1% power and the engine does not response to throttle input in the slightest.

 

My fix so far has been to just pull the negative terminal off and reset the computer, then the car goes back to the way it was. It seems to cause the issue when i floor it. I think i know the root cause of the problem, which is a simple fix, i just want to see if replacing the pedal (which is what the maxima guys recommend) will actually fix the issue.

 

Thanks guys.

 

-Kyle

[Citron]

The R50 is fly by wire, not throttle cable? 

 

If so, you should be able to disconnect the plug at the pedal, put a meter across the potentiometer, put it on ohms. Press the pedal with the car off, and see if you have a smooth change. Or backprobe the plug with everything in service and car running and actually watch the voltage. It should be smooth, not jerky and no flat spots. That should tell you if the pedal is actually bad. 

 

I hope that makes sense? It does in my mind. 

[Slartibartfast]

IIRC the last two years of the R50 had drive by wire. My dad's '03 did. It was one of the things I didn't like about that truck.

I had a look at the FSM and the short answer is to try what Citron said. The sensor's got two separate pots in it, presumably so they can't both fail at once, and they're wired straight to the plug so that you can actually test them. Unhelpfully, the manual does not list their resistance, only their voltage outputs with the key on, engine off, MT in first or AT in D (no idea why). The first pot has two blue wires and a black/red wire, the second has a white with red, a red, and another blue wire (was there a sale on blue wire?). Sensor 1 (one of the blue wires, the one that's not steady 0v or 5v) should be 0.5 to 1v (measure its voltage to body ground, not to one of the 0v wires, apparently the ECU doesn't like that) with the pedal released, 3.9 to 4.7v with it floored, and sensor 2 (the red wire) should be 0.15 to 0.6v released and 1.95 to 2.4v floored. The graph shows straight lines, so yeah, if one of them drops out or bounces around then you've found your problem. Looks like you can also check all of this through OBD live data (SEN1 , SEN 2, and CLSD THL POS), but the ECU tweaks the numbers on one of them for some reason. If you do replace the sensor, the manual says to do three (!) different relearn procedures afterwards. All this starts on EC-708 of the '03 manual.

I'd want to see if the sensor can be disassembled and cleaned. Maybe there's just some schmutz in there that a wiper's riding up on, and a shot of contact cleaner would resolve the problem without having to teach the computer how to tie its shoes again afterwards.

Good luck!

[hawairish]

Drive by wire (03-04) is one thing I hate about the truck.  Stupid codes that disable the truck, plus "non-serviceable" throttle body and pedal.  I had a P2135 (Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation) that put my truck into limp mode maybe 5 times randomly over the course of 2 years, and caused random super-light surges that wouldn't throw codes (but would cancel my cruise if set).  The proposed solution was to replace the throttle body.  Rather than drop $150, I made the unit serviceable by drilling out the rivets then cleaned all of the contact points.  No issues since.

 

What Citron and Slartibartfast mentioned is what the FSM says, but I'd definitely pull the pedal and take it apart to see if any of the sensors can be cleaned.  If the sensor has markings, you may also want to check Digi-Key for a replacement component rather than a whole new pedal, if you have the means to repair it (and if the switch can even be replaced).  I did something similar for the shifter release switch on my transmission...$1 exact replacement part and some soldering.

Edited August 16, 2018 by hawairish