Throttle Position Sensor P0121
Thread Starter
Cruising
Joined: Mar 2007
Posts: 13
Likes: 0
From: SoCal California
Throttle Position Sensor P0121
A few nights ago, I was cruising on the 134 here in Los Angeles. After hitting a bit of traffic I realized my 96 LT1 automatic would not shift up into 3rd gear, and then noticed that the "Service ASR" and "Service Engine" lights were on.
I pulled over and checked the code on my OBD/II reader and it said the problem is related to the throttle position sensor (P0121). I was able to drive home on back roads, however shifting between 1st and 2nd gear became progressively worse, sometimes not shifting until after 4,500 RPM.
Anything I should try before taking it in to have the TPS replaced?
I pulled over and checked the code on my OBD/II reader and it said the problem is related to the throttle position sensor (P0121). I was able to drive home on back roads, however shifting between 1st and 2nd gear became progressively worse, sometimes not shifting until after 4,500 RPM.
Anything I should try before taking it in to have the TPS replaced?
Drifting
Joined: Nov 1999
Posts: 1,502
Likes: 12
From: Yorktown Heights NY
Get one from Rockauto.com and replace it yourself 
I've done this and it's not rocket science.
Disconnect your battery cable for 30 seconds after you change it to have the ECM relearn the new TPS.
I have the original GM programmmer for doing this, but I think you can also do it with the above method.
Maybe someone else can confirm.
As far as your syptoms and the code reader is concerned I think the TPS is your problem
I've done this and it's not rocket science.
Disconnect your battery cable for 30 seconds after you change it to have the ECM relearn the new TPS.
I have the original GM programmmer for doing this, but I think you can also do it with the above method.
Maybe someone else can confirm.
As far as your syptoms and the code reader is concerned I think the TPS is your problem
Intermediate
Joined: Sep 2007
Posts: 29
Likes: 1
From: Tyler Texas
I had the same problem about two weeks ago with the same code (as well as P0121). My wife and I had just returned from a 1800 mile round trip so we were luck we weren't stranded on the road. I don't know if the solution will be the same but my problem was the 5VDC reference voltage to the TPS was setting the trouble code. Another symptom I experienced at the very same time was my A/C compressor clutch would not engage. I tried to trouble shoot the problem for almost a full day until I went to pins 28 & 29 on the black connector to the ECM and checked the reference voltage output there. It was but neither the TPS or the A/C high side pressure sensor had it. I couldn't find where the wire were cut/worn through so I pulled both pins and ran new wires to both sensors.
You might want to reference the enclosed link for further information to see if it helps you any. Good luck.
http://www.corvette-guru.com/modules...=14481&forum=1
You might want to reference the enclosed link for further information to see if it helps you any. Good luck.
http://www.corvette-guru.com/modules...=14481&forum=1
