LBZ: HELP please. No throttle issue

[AUSDMAX]

Ok so i have a problem iv been trying to trace down all week i have no throttle as in the engine will not rev at all. It starts and idles fine but throws these 3 codes

P2122
P003A
P2563

i have checked all the wiring on the pedal back to the ecm and checked the 5 volt signal wire and all is good iv re set the codes and still nothing iv also ordered a new position sensor for the turbo as that is one of the codes but unplugged that to see if it would rev but still nothing...

any help would be awesome. Cheers

 

[AUSDMAX]

Anyone. ..... this is doing my head in iv tried everything!

 

[gmpat21]

p003a and p2563 both relate to the turbo vane position sensor one being performane and one saying it is not learned. do you have access to a scan tool or with the truck running unplug the turbo vane actuator solenoid and see if you get throttle. how many miles on truck?

 

[RPM Motorsports]

I'd be looking into why you have a low input signal to the petal. Is this a new swap, or a prior running vehicle. We need more info. If its a new swap, I bet you have the wrong petal assy.

 

[Poltergeist]

Moving to Hard Parts.

 

[AUSDMAX]

Its a new swap just did it I have checked all the voltages to the pedal and all the checks have come up sweet im using a pedal from an lmm 4500 kodiak I believe it was out of I have the part number here somewhere iv used them before on these swaps. I have efilive can I do a sensor relearn with that?

 

[AUSDMAX]

gm part #15274609

this is the pedal im running

 

[JoshH]

Have you back-probed the TPS signal wires to see what they are showing for voltage as you move the pedal through its range? Also, have you checked with a scan tool to see what the ECM is showing for each circuit of the pedal?

The pedal you're using is for a medium duty application. Maybe they use a different voltage on the pedal than the pickups do. Since you're running a pickup OS, that could be what is causing your problem. Do you have a pedal assembly from a pickup you can try?

 

[AUSDMAX]

it had a quick look then and its reading 20% throttle with no throttle at all i need some batteries for my meter then i can probe it what sweep should i get on the out put voltage wise? and where can i find the ecm outputs that show the output of the pedal circuits on efilive?

 

[catman3126]

you got an issue with that sensor. should be 0 to 5 volt sensor. in the scan tool select the PID for throttle position sensor voltage.

 

[JoshH]

My truck shows .96 V at 0% and 4.22 V at 100% on circuit 1, and circuit 2 shows .47 V at 0% and 2.10 V at 100%. With EFILive, you can check it with APP1 (Accelerator Pedal Position - Sensor 1 (V)) and APP2 (Accelerator Pedal Position - Sensor 2 (V)).

 

[AUSDMAX]

thanks josh ill finish my dinner and head back to have a look and see what the voltages say thanks as always :thumb:

 

[AUSDMAX]

ok so i checked pedal voltages im getting 3.9V then dropping to 0.7V on APP1 while depressing the pedal and on APP2 im getting 0.5V dropping to 2.1 on APP2 while depressing the pedal i checked these via EFILIVE

 

[AUSDMAX]

it sounds like my pedal is reading backwards to josh's on APP1 circuit

 

[JoshH]

It must be because it is a medium duty pedal assembly. Can you get a pedal assembly from a pickup to try?

 

[AUSDMAX]

no not around here unfortunately Josh i was sure this was the same pedal i used on my last conversions how ever i must have written down the wrong part numbers i will have to order one from the US dahm Australia and not importing more duramax trucks

 

[jkholder09]

IIrc the app sensors are negative correllation on gm's.
this is a fail safe so that one sensor is high to low and the other is low to high.
Also they would have one measure 0-2.5 volts and the other 2.5 to 5 volts. This was so that a short to signal could be easily detected.
The diesel trucks never really had app sensor problems so I have not gotten into them really deep.
The voltages you listed do not sound quite right. Could they be wired up incorrectly?
Please also double check my theory with an actual description and op from a service manual, I am going off memory and its been a while since I worked at the dealer.

 

[AUSDMAX]

i have no service manual or anything im only going by what Josh has posted my signal is opposite to what Josh's is reading so im just assuming that this could be my culprit

 

[AUSDMAX]

ok so i reversed the polarity on the app1 circuit and now it reads perfect the same as josh's 1V to 4.2V on the app1 circuit while pressing the pedal in so that is sorted but still nothing iv also noted that in my logging while checking all of the sensors my throttle position stays a continuous 99.6% TP and does not change while depressing the throttle pedal this is confusing the hell out of me

 

[AUSDMAX]

Ok so after reversing the polarity on the APP1 sensor (backwards now to how its meant to be stock), re setting the truck, re-flashing in a stock tune and then re-flashing on my dsp5 tune back in we have throttle!!!! Thanks to everyone who helped I think its all good now I must have a freak pedal iv ordered some more for more conversion so ill plug one in when they show up and just see if these ones are different!