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Discussion Starter · #1 ·
I've looked all over the Web, different forums, and even the FB groups, and have yet to find a permanent solution.

Car description is in my signature,

I've fixed all the emissions codes, but I keep getting a recurring P2135 (throttle pedal position voltage correlation A/B) or something to that effect.

Steps I've taken to fix it:
•Removed and cleaned throttle body (did the throttle relearn procedure)

•Replaced throttle pedal assembly. (Did the pedal position relearn as well)

And when this happens, I can usually cycle the ignition (on 2 sec, off 10 sec x 2) and it'll start and actually rev past 1800rpms,

But in the event I'm in a hurry to get somewhere, it's frustrating to have to find somewhere to pull over and do that. Especially at night.

The only thing I haven't done, is replace the ETB, or replace/check my battery ground. There was a lot of corrosion on both terminals, just replaced the positive terminal assembly recently, but haven't done the ground yet.

I read that it's been a fix for some to replace the negative cable, so that's probably what I'll do next, as I have 00g cable and a brand new terminal.

Hopefully it's not the ETB, so I'm interested to see what other ideas that the community comes up with, as I really like this car, but I'm rapidly losing my patience.

TIA
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The problem is in the Throttle Body or wiring. It has nothing to do with the pedal sensor (APP), that's a whole different set of codes. The TB has two potentiometers built in which work opposite one another, see the graph below:
Font Rectangle Material property Parallel Slope

The reason the system is configured that way is because the percentage difference between the two signals will be the same at any supply voltage, even though the "height" of the X is different. That allows the ECM to compensate for any problems in the 5V sensor supply. The P2135 is telling you neither one of the signals is flatlined (that would cause a P0122 or P0123) but one of them is producing an incorrect voltage. Some Nissans have separate supplies and grounds for each of the sensors, but on VQ Altimas the power and ground is common:
Rectangle Line Parallel Font Slope


That means problems in the 5V supply or ground can't affect just one sensor. So the cause of the problem is limited to a bad signal wire from a sensor to the ECM, or a bad pot in the TB (in which case you need a new TB). Here's the layout for the TB connector (note that the WD has a typo, the connector is actually F57):
Font Rectangle Line Material property Parallel

Pins 2 and 3 should show voltages approximating what's on the graph at various throttle positions. If they do then you have a bad wire, if they don't then you have a bad TB.
 

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Discussion Starter · #3 ·
The problem is in the Throttle Body or wiring. It has nothing to do with the pedal sensor (APP), that's a whole different set of codes. The TB has two potentiometers built in which work opposite one another, see the graph below:
View attachment 11396
The reason the system is configured that way is because the percentage difference between the two signals will be the same at any supply voltage, even though the "height" of the X is different. That allows the ECM to compensate for any problems in the 5V sensor supply. The P2135 is telling you neither one of the signals is flatlined (that would cause a P0122 or P0123) but one of them is producing an incorrect voltage. Some Nissans have separate supplies and grounds for each of the sensors, but on VQ Altimas the power and ground is common:
View attachment 11397

That means problems in the 5V supply or ground can't affect just one sensor. So the cause of the problem is limited to a bad signal wire from a sensor to the ECM, or a bad pot in the TB (in which case you need a new TB). Here's the layout for the TB connector (note that the WD has a typo, the connector is actually F57):
View attachment 11398
Pins 2 and 3 should show voltages approximating what's on the graph at various throttle positions. If they do then you have a bad wire, if they don't then you have a bad TB.
Thanks sir, I do appreciate it!! I went to school for Auto electrical diag and repair, and I should still have a multimeter laying around unless my ex's boyfriend stole it.

Definitely going to check voltage and see if it's the ETB or a plug somewhere.

I've babied this car since I bought it, only wish the air worked and it had cooled seats, but other than that, I'm going to keep it until the wheels fall off.
 
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