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2003 chevy trailblazer_lt
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4 Posts
Discussion Starter · #1 ·
Hey everybody...i'm a newbie here...this is my first post...and it's a dewsy!! I have an 03 trailblazer lt 4.2...i have the code p1271 reduced engine power popping up intermittantly...i've gotten all kinds of diagnostics done...replaced accellerator pedal and sensor...the throttlebody and the fan clutch...checked the wiring harnesses...just recently p1271 showed again reduced engine power and threw my truck into limp mode...back to the garage i went...a diagnostic showed an app sensor 1&2 correlation problem...app 1 was at 4% and app 2 was at 0%...they suggested that the aftermarket dorman pedal i replaced may have a bad sensor and should be replaced again...in the process of doing this now..hopefully this fixes the problem but i have my doubts...if the code comes back they're going to check the pcm...apparrently the computer is sending out 5.03 volts instead of the normal 5 volts it should ...this whole process has me very confused and stressed to say the least....any suggestions or help from any techies out there would be greatly appreciated!!
 

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2004 gmc envoy_sle_xl
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1,239 Posts
IT IS NOT COIL PROBLEM, LOVEROTTIES, DON'T STEER PEOPLE IN WRONG DIRECTIONS!!!

The 5.03V that the PCM is putting is correct and well within tolerance. What needs to be checked is whether the 5V is getting to the pedal sensors and the throttle body sensors. And if there is an intermittent condition going on. You may have a wiring issue in a harness.

This problem needs for a technician to get in there with a meter and start checking voltages.
 

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2002 chevy trailblazer_ltz
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2,762 Posts
WOW! your the pro I guess! well it happened to me that way and I bought one coil and checked all connections and it fix the problem now over a yr! Not garentee the same but it's a cheap way to maybe the same fix!Wish I had your money to though a way .
 

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2004 gmc envoy_sle_xl
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1,239 Posts
I am certainly not a pro or an expert, but the guy is showing a P1271 code which is related to the accellerator pedal problem. And that is what needs to be troubleshot. My advice to him concentrated on that area.
 

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2003 Chevrolet Trailblazer LT EXT
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454 Posts
Do yourself a BIG favor.
Stop at the local dealer and buy yourself a genuine accelerator pedal from the good people that built the truck in the first place.

I went though no less than 3 aftermarket accelerator pedals until a factory part was purchased. (grew tired of mailing back the defective parts for free exchanges)
Immediately, the problem went away and that was almost 2 years ago with no repeat problems.

The aftermarket people do a GREAT job manufacturing all other categories of parts. It just seems that the factory boys cant be matched on the accelerator pedal on these trucks.
Speaking from my personal experience.
 

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2003 chevy trailblazer_lt
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4 Posts
Discussion Starter · #8 ·
Thanks for the input guys...My gut feeling is that its either the aftermarket pedal i put in or a wiring harness issue...allthough a couple of mechanics have said that in all their years of experience they have'nt seen to many aftermarket dorman products fail...not to say that this pedal hasn't...as far as the pedal goes it was tested today...live data showed that app. sensor 1&2 disagree in values...app1 was at 4% and app2 was at 0%...they tested all referance voltages and circuits for shorts and opens back to computer and no problems found...that would lead me to think that the pedal is at fault or a wiring issue from the pedal to the computer or the throttlebody to the computer...remember the throttlebody is new....this code p1271 is frustrating the hell out of me!! And again i emphasize the fact that its very intermittent....HELP!!
 

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2003 chevy trailblazer_lt
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Discussion Starter · #9 ·
One more quick question...I was told that the accellorator pedal only has 1 sensor in it....so app1 and app2...one of the sensors being the pedal...app1..is app2 the sensor in the throttlebody? So isn't that telling us the problem could be the wiring from the pedal to the throttlebody?
 

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2004 gmc envoy_sle_xl
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1,239 Posts
The accelerator pedal has two variable resistors and when the output from them does not match, the PCM sets the P1271 code and puts the engine in reduced power mode. The throttle body butterfly actuator also has two variable resistors and these are also checked by the PCM. If the output from them does not match a different code is set.

Take the advice of the previous poster and use OEM Accelerator Pedal sensors.
 
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