I have a 2002 Trailblazer with an intermittent p1271 (only) error code with a REP light. I have replaced the accelerator pedal assy several times with each assy having a different length of time before the error code would come back; the first assy lasted a year! I purchased the assy from NAPA so it has a lifetime replacement warranty.

I have read all the threads concerning the 5v reference being shorted to ground through the clutch fan so I unplugged the connector and the error code and REP reoccurred. I inspected and cleaned the throttle body, didn't help and lastly I inspected the wiring harness and app connector; I didn't find any high resistance from the connector to the PCM in any of the six wires of the APP. I have my own scanner so all error codes are cleared after each event.
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My question to all the pundits out there is; could aftermarket APP assy be that bad that I would get three of them to fail? I would like to cure this issue once and for all so any insight would be greatly appreciated.<O</O

 

Are you sure you testing for short to grd correctly? You shouldn't have any continuity when testing for short to grd.

disconnect the 65 pin, blue c1 connector at the ecm and the app sensor connector. check for short to grd at pins 10, 11, 1, 2, 55, 63 of the ecm connector.

backprobe the pins so you don't damage the connector pin fit. with an ohmn meter, connect 1 meter probe to chassis grd and the other to one of the pin terminals. it should read OL or open if the wiring is good. If you have any reading; the wire is shorted to grd. repeat for all pin terminals.

 

Thanks for the prompt response Tech2.

I was checking for high resistance in the wiring, not a short to ground. However, to cover all my bases I can whip that out in no time; it's my wife vehicle so I have to wait till she returns from work. In the mean time, wouldn't a short to ground in that wire bundle be pretty unusual and cause other error codes with the p1271?

Thanks for your time

 

honestly not 100% sure how many codes would be tripped...its possible that if the chaffed wire is only on the app circuit you would only see dtc there. The test will rule it out.

as your into multiple app sensors I'm betting you have a intermitent electrical issue and not a bad part.


What are the freeze frame failure records for the app1 and app2 voltages are when the code set?

 

i have a 2002 chevy trailblazer & it keeps tripping app codes & the engine keeps going into limp mode when driving if you reset codes it will usually do it again when shifting into gears. changed pedal, throttle body & checked wiring still no luck. Any suggestions please?