Need a few pointers on p1271/p1275

[plaen]

I've recently inherited a 2002 TB I6 195,700 mi with two codes, p1271 and p1275, for APP sensor 1 high voltage after reading the posts here, the old site, and some on Google, the following have been done and both still come back after clearing the codes:

Replaced Throttle body (replaced by dealer mechanic prior to inheriting)
Disconnected the fan clutch at the shroud(Me, Didn't make it 100 ft before REP)
Disconnected the battery to relearn the new TB(didn't appear to have been done after TB replacement)
Checked fuses with meter, none needed to be replaced
Checked wiring to APP and fan clutch(On shroud) and at the firewall boot(as best I could without taking apart the loom and lower dash)
Removed random ground wire from negative terminal to bolt on the PCM(No idea who put that there)
Checked grounds for corrosion and tightness

I do have a DMM, but it does not have a min/max setting, and I don't have access to a tech 2 just a BT ODB II adapter with Torque. I do have my lifted 02 to pull parts off to test, and am going to swap the APP tonight and see if the problem follows. It does seem to be when the PCM commands the fan on/off, but disconnecting the clutch harness made no difference. After initally resetting the codes, it drove fine for 60+ miles with a few hours between turning off the car and starting again from replacing shocks, fluids, and end links. The following day, did it 16 times in a 10 mile drive with it needing to be shut off and restarted to clear the REP

Any ideas on what to check next?

 

[Wooluf1952]

Is it possible one of the APP sensors is bad?

 

[plaen]

Is it possible one of the APP sensors is bad?

That's what I was thinking, just got done swapping a known good pedal, cleared the codes, and didn't come back on in the 2-3 mile drive, and the original pedal I swapped into my other tb and the rep didn't pop up on it.

Before clearing the codes, p1280 also came up, in addition to the 1271/1275.

It does appear the pedal was replaced with a Dorman one before I got it, some have seen problems with the after market ones. Found out a little more information about the car, the rep initially started a year ago, the owner took it to a gm dealer and it hadn't came back for a year until now.

 

[kyle931]

I bought an 02 trailblazer 3 months ago and soon got the Service Engine Soon light and Reduced Engine Power light. I invested in a $60 code reader from Auto Zone (the best investment that I have ever made). I pulled up the code on the code reader and it read p1271 and p1271 p/d which means Excessive voltage difference between Accelerator Pedal Position Sensor 1 and 2. After looking at my Hayne's manual and forums I decided to order a new APP Sensor which is built into the gas pedal. I went cheap and bought the Dorman OE replacement APP Sensor fir $70. For those of you who don't know, OE is a cheaper (in both ways) version of the original part. I put the new APP sensor in and it ran without lights or codes for a few weeks before getting the SES and REP lights. After tons of forums, checking wires, a throttle body, and later I found on a forum that the Dorman OE replacement is junk and there is a high chance of it going bad after a few weeks. I am about to buy an OEM replacement and I will keep you posted on how it turns out.

I have found a lot of people on forums with no decent answers, so hopefully this helps the people in the same boat as myself.

 

[The_Roadie]

...I have found a lot of people on forums with no decent answers,...

Welcome! I bet I know ONE forum that used to have decent answers and a lot more active posters, but they're all here now.

 

[kyle931]

Welcome! I bet I know ONE forum that used to have decent answers and a lot more active posters, but they're all here now.

That's why I came here