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My apps is acting wierd no codes but no pedal if t clear on…

Customer Question
my apps is acting wierd...
my apps is acting wierd no codes but no pedal if hit clear on scanner will have pedal for a few seconds
Submitted: 2 years ago.Category: GM
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Customer reply replied 2 years ago
accelerator pedal position sensor is what i mean by apps, i have power on one of the pins with a test light, when i unplug the sensor i get a reduced engine power message on the dash, when i hook my scanner to it says no codes if i hit clear i get throttle for a few seconds then it goes away till i hit clear again yet still no codes on scanner or check engine light on the dash this a 2005 chevy 3500 6.6 lly duramax
Answered in 30 minutes by:
8/21/2015
GM Mechanic: GM Tech (Cam), GMC Mechanic replied 2 years ago
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 30,417
Experience: GM Grand Master Technician 2007. 14 years experience.
Verified
Hello, I'm Cam.
Can I get your first name please?
So the fault may not set the CB eck engine light but does your scanner show you if any codes pending? The issues that I've seen around this with the pedal position sensor itself, the wiring to the sensor, or as strange as it sounds the turbocharger position sensor. The Accelerator pedal position sensor uses three different sensors inside of it, each with a separate 5 V reference. One of the other sensors sharing any of these reference voltages could be dragging that voltage down in setting this issue. Finding which one could be a pain, and have to use the scanner that will view live data from the engine control module, and from there we see which sensor. The computer supplies and monitors each five reference, so if one of them is low then we need to change that one down.
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Customer reply replied 2 years ago
my name is ***** ***** what should i try now?
GM Mechanic: GM Tech (Cam), GMC Mechanic replied 2 years ago
the next step Justin is to figure out which voltage is down. To do that we need to get our hands on a full function scan tool that shows all of the ECM values including the Five volt references I spoke about.
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Customer reply replied 2 years ago
ok so hook it up and then do what?
GM Mechanic: GM Tech (Cam), GMC Mechanic replied 2 years ago
You hook the scan tool up and then navigate to the live stream where you would see engine speed and throttle position and such. You will navigate down to the reference voltage is in with the key turned on but the engine off, tell me what the voltages for reference one, reference two, and reference three. From there I can tell you which sensors share the same reference voltage so that you can start unplugging the sensors to see which one returns the voltage to normal. If one of the sensors it shorted out inside, it would drag the whole line down.
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Customer reply replied 2 years ago
this scanner im using has live data but wont let me click on it trying to find a good one
GM Mechanic: GM Tech (Cam), GMC Mechanic replied 2 years ago
Ok.
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Customer reply replied 2 years ago
ok got a good scanner getting code p0101 which is mass air flow sensor do you think this may be the cause?
GM Mechanic: GM Tech (Cam), GMC Mechanic replied 2 years ago

Yes, very possible. Is the air filter plugged? Dirty Mass Air Flow sensor (MAF) sensor in the duct? Plugged exhaust? charge air cooler line popped off?

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Customer reply replied 2 years ago
its a twin turbo truck
GM Mechanic: GM Tech (Cam), GMC Mechanic replied 2 years ago

Its modified to add a second turbo? Factory it only came with one.

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Customer reply replied 2 years ago
its a built truck has compound turbo setup
GM Mechanic: GM Tech (Cam), GMC Mechanic replied 2 years ago

OK, so lets check that Mass Air Flow sensor (MAF) sensor then. I am not sure where it would be in your setup, does this share a single air filter?

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Customer reply replied 2 years ago
what do you want to check on it the air flow or what?
GM Mechanic: GM Tech (Cam), GMC Mechanic replied 2 years ago

Dirt on the sensor, even consider unplugging the sensor and see what that does.

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