P2123 Engine Limp

[durallymax]

Working on 06 LBZ that was going into engine limp. Only code was P2123. I've had troubles with APPs before so for $50 for the entire new assembly, tried the cheap part first. No luck there.

Going to go page through my books but they are for 03 which uses a different assembly, not sure if the diagnostic values would be similar or not.

anyone else have other ideas. Truck has EGR deleted but it has not been tuned or turned off in the tune. EGR was deleted well over a year ago.

 

[messejme]

Check the wiring supplying power to the accelerator pedal rheostat. maybe a bad connection or chaffed wire.

 

[durallymax]

I will try that thanks.

 

[durallymax]

I have the following readings:

APP 1: Rest:1.0v, Full:4.3v

APP 2: Rest:0.5V, Full:2.2v

APP 3: N/A


My books for 03 show the values for the 03 sensor and they are completly different. I know the pedals and such are different too so I wonder if they changed a lot with the newer ones.

Thanks.

 

[blk smoke lb7]

We have an 07 book but I souldnt be able to check untill I got home

 

[messejme]

I think the .5v is too low , shoulnt be less than .806v

 

[chevyburnout1]

Normal range for APP1 is 0.90v - 4.35v. APP2 is 0.43v - 2.15v.

Were those readings from a scan tool/V2? Or actually measured at the pedal?

A high voltage code usually means a broken wire somewhere.

 

[jmaz268]

Pulled this off aldata for my 01.

APP 1-3-Range 0-5 Volts : The ECM uses the APP sensors to control fuel delivery as requested by the driver. Three APP sensors are located in a module at the base of the accelerator pedal. The ECM only requires information from one sensor, the other two serve as a fail safe. APP 1 should read about 0.35-0.95 volts at idle to above 4.0 volts at wide open throttle.

 

[chevyburnout1]

Scratch that. High voltage code on this circuit means a wire may be shorted somewhere. Either that, or the ground reference to the pedal is open or has high resistance.

 

[durallymax]

My book shows that it must have went over 4.5v at one point. I massaged the harness for awhile with no luck guess ill keep looking.

Readings were with v2

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[x MadMAX DIESEL]

Does this code reduce power?

 

[x MadMAX DIESEL]

I have this code set to not reported, no mil and there is still a check engine light and a code. Also my 3rd gear start tune isn't working anymore

 

[Cornell]

Gotta bump this before making a new thread.

My regular cab short bed LBZ threw this code tonight while I had it sitting outside for awhile warming it up because its 0 degrees outside. Its parked in a heated shop when not driven... I cleared it with my V2... sometimes it throws it right away again and sometimes it goes for a couple minutes without throwing the code. I checked the wiring, is the best bet to replace the throttle position sensor next?

Also it goes into limp, 30mph max in 3rd gear ~2000rpms

 

[Cornell]

Ended up being the pedal.