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Discussion Starter · #1 ·
I have the PO120 and PO2135 codes, I replaced the throttle bod, pedal assembly, TPS plug and nothing helps. Truck is in limp mode and will barely idle if you press the brake pedal it will try and die, any ideas on what's causing this? Also I cleaned and replaced all ground wires.
 

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The P0120 is a throttle position sensor (on the throttle body), or the pedal position sensor, on the gas pedal.
The P2135 is from the same area, I think I'd inspect the wiring between the two.
 

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2000 Silverado Z71 4x4 5.3L 480k+ miles w/ GM rebuilt motor and trans
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The P0120 is a throttle position sensor (on the throttle body)
TPS is built into the throttle body by 2003 on the Silverado. Probably the same for the Sierra. If he did the throttle body, then he swapped the TPS. I don't see any mention of the Pedal Position Sensor in the code definitions I've found for P0120...?

Found this link to be helpful. I used a similar procedure on my separate TPS. Maybe the new TB is bad. Wouldn't be the first time...

@Prince5kids I'm assuming the dash is saying "Reduced Engine Power". Did you get the new TB from a junkyard or is it actually new? Have you gone through ALL of your fuses? Did you reset the computer by disconnecting the battery and touching the cables together and/or letting it sit for a while?
 

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Discussion Starter · #4 ·
TPS is built into the throttle body by 2003 on the Silverado. Probably the same for the Sierra. If he did the throttle body, then he swapped the TPS. I don't see any mention of the Pedal Position Sensor in the code definitions I've found for P0120...?

Found this link to be helpful. I used a similar procedure on my separate TPS. Maybe the new TB is bad. Wouldn't be the first time...

@Prince5kids I'm assuming the dash is saying "Reduced Engine Power". Did you get the new TB from a junkyard or is it actually new? Have you gone through ALL of your fuses? Did you reset the computer by disconnecting the battery and touching the cables together and/or letting it sit for a while?
Yes the dash says it, I did get a new one, all fuses are good and I disconnected the battery for an hour.
 

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2000 Silverado Z71 4x4 5.3L 480k+ miles w/ GM rebuilt motor and trans
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The P2135 is from the same area, I think I'd inspect the wiring between the two.
I don't see any mention of the Pedal Position Sensor in the code definitions I've found for P0120...?
Had a brain fart, Ray. Didn't register the rest of the information...

Service bulletin for the next generation of vehicles and their faulty TPS.
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Seems relevant. If you cannot find a nicked or broken wire and have traced the wires out (starting with Dark Green), I would verify with a scan tool these 2 internal sensors agree. You said you replaced the plug already, which means it's unlikely you have bent pins in both new components (TB & plug).
 
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