i own a 2003 silverado 1500hd , 6.0 auto. my problem is for no apparent reason and at completely random conditions the throttle will surge when driving (at no particular speed) 2 or 3 hundred rpms up and down , sometimes it goes into "reduced engine power" mode , sometimes it dosen't. it is showing the same code every time on a snap on scanner(1125) saying that the throttle sensors are not in sync, i replaced the one on the pedal, are there more??????? the truck has only 71,000 on it and is completely unreliable as is. has anyone else had this happen?? can someone help me????????? i also cleaned the tb and although it couldn't have hurt, it sure did'nt help either! i am at wits end and almost out of cash , any suggestions would help!

 

The throttle position sensor is actualy on the throttle body. It is on the drivers side and is the lower of the 2 sensors located there. The other is the Idle Air Control Valve which could probably be removed and cleaned as well. Are you sure it is a 1125 code...I am not familiar with that one. 1121 and 1122 are both throttle position sensor circuit voltage high and low respectively. I would check that sensor. Let us know what you find out.

 

i looked on the throttle body and there is no tps there, the only plug in is on the passenger side. does this mean i have to replace the entire throttle plate to replace the tps? also there is some kind of sensor on the top of the intake directly behind the throttle plate that is really loose and cannot be tightened up. what the heck is this? the code is 1125 app sensors out of range, i've heard that the plastic gears on the throttle blade control are bad about stripping out......it looks like this is gonna cost me a bundle....

 

I think what you are calling the throttle blade control is actually the throttle position sensor.

 

www.chevythunder .com shows basic components and where the tps should be, where that pic shows the tps and the sensor above it, mine is just plain metal, no holes no nothing, i'm just a shadetree mechanic and i am confused!!!

 

Pictures so we can see what you are describing to us so we can possibly help...
Possibly some broken or loose wires? Dirty MAF sensor?

 

Sorry I forgot that 2003 is the first year that the "drive by wire" throttle body was used. It has to be computer related b/c it controls everything throttle related. You should not have a throttle cable, just a large module on the passenger side of the T.B. right?

 

Bad connection, broken wire maybe. Shorted out electric motor in the throttle body throttle controler on the throttle body? Computer as mentioned...

 

well, the problem is fixed but it did cost a lot to do it. whoever had this truck before me had evidently ran the cheapest gas possible all the time. even though i cleaned the throttle body it was too late and the damage was already done. one of the plastic gears on the throttle flap had 3 teeth missing allowing the plate to rock back and forth at cruising speed and that is what was causing the surge, the reduced engine power light was coming on because the accelerator position was not matching the throttle position. anyways, replaced the throttle body, new wiring harness(updated design), and reflashed the comp. grand total of $637.81. that really sucks. CLEAN YOUR THROTTLE BODY AT REGULAR INTERVALS AND RUN PREMIUM FUEL IF YOU WANT TO PREVENT THIS FROM HAPPENING TO YOU!!!!! hope that this bad experience for me can help some of you guys save some money down the road!

 

How can running the cheapest fuel possible damage the throttle body gears that control the butterfly flap when the fuel does not even run by it? I can understand the regulr cleaning and inspections though...