wtnhunt Posted August 24, 2007 Report Share Posted August 24, 2007 Any other mechanincs out there, need a little help. Having a problem with our gmc yukon, got a 350 with throttle body injection in it. When sitting in traffic at school to pick up the kids it will run a little warm, but not hot, the alternator drags down some too and more and more frequently we are getting a service engine soon light. The engine code is for the throttle position sensor, and usually after it trips the service engine soon light, the transmission will act weird between shiftings from first to second gear. Had autozone check the computer for me and they said it is the tps. I wanted to check the wiring for it before getting the non refundable part to make sure it was not a wiring issue. Have had mice get in it in the garage over last winter and thought it might be in the wiring possibly and wanted to rule that out. The guy from autozone said the sensor was under the air cleaner intake at the throttle body. I looked and am not finding the part that looks like what I think it is supposed to look like, do I have to remove the throttle body to get to it? From what I am understanding, you can check for 5 volts at the sensor and if it is getting 5 volts the wiring is probably ok. Guess my questions really are where exactly is this sensor, and does it have a tendency when going bad to act flaky and give intermittent trans shifting issues? Quote Link to comment Share on other sites More sharing options...
Newarcher Posted August 24, 2007 Report Share Posted August 24, 2007 I found the problem.....gmc yukon New Quote Link to comment Share on other sites More sharing options...
MUDRUNNER Posted August 24, 2007 Report Share Posted August 24, 2007 Sounds like the TPS to me.I had a similiar problem on a truck I had a few years ago.I believe the part is relatively cheap. If you remove the air cleaner I think it should be on the passenger side of the throttle body.If I remember correctly it just has two screws and a plug that holds it in place.Should be an easy fix, and I think is a pretty common problem. I'm not positive,the surging and slipping might not be a tranny problem at all.It could just be that the sensor is cutting of fuel making it lug,then surging when it kicks back in. Let us know how you make out. I found the problem.....gmc yukon Always one in the buch isn't there. Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted August 24, 2007 Author Report Share Posted August 24, 2007 Always one in the buch isn't there. LOL, Yep:rolleyes:. Think I found the tps, but it is on the drivers side on the side of the throttle body. Did pull the plug off and was getting 5 volts at the plug with the ignition on but not with the engine running, so it is probably not the wiring. They are about $45, so I guess I will pick one up from autozone and replace it and hope it solves that problem. Quote Link to comment Share on other sites More sharing options...
Mirage Posted August 24, 2007 Report Share Posted August 24, 2007 You can check the tps with a simple digital volt meter. Put it on the ohm scale, unplug the sensor "it is on the drivers side of the throttle boody and has three wires going into it. connect the red leed of the dvm to the term a and the black to term b now slowly open turn the sensor and if the sensor is bad the meter will show open or ol. the tps tells the ecm when to shift thats why your tranny is acting funny more that likely I have replaed many tps on your style truck Quote Link to comment Share on other sites More sharing options...
MUDRUNNER Posted August 24, 2007 Report Share Posted August 24, 2007 LOL, Yep:rolleyes:. Think I found the tps, but it is on the drivers side on the side of the throttle body. /quote] You can't pay attention to too much I say. It was about 7 or 8 years ago when I changed it and it was on a '90 Chevy truck.That's way too far back to remember all the little details. Hope you get her fixed up. Quote Link to comment Share on other sites More sharing options...
Mirage Posted August 24, 2007 Report Share Posted August 24, 2007 im sure its the tps, I think it takes a torx15 to remove the tps from the throttle body unit. Quote Link to comment Share on other sites More sharing options...
Shaun_300 Posted August 24, 2007 Report Share Posted August 24, 2007 Yep sounds like the TPS to me too. I'm also about 90% sure that you'll need a T-15 to take it off, if it's not it'll be a T-10. Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted August 25, 2007 Author Report Share Posted August 25, 2007 Yep, two torx screws on the side. Thanks guys, will replace that part this weekend and hopefully that will resolve it. Quote Link to comment Share on other sites More sharing options...
Leo Posted August 25, 2007 Report Share Posted August 25, 2007 Don't know for sure on the GMC but most "Computer" driven check engine lights need to be reset by disconnecting one battery terminal for a couple minutes. If you don't reset the thing even though you changed the part the light may remain on. To top it off a diagnostic will still show that part as being faulty even though you know you replaced it. Don't forget that step Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted August 25, 2007 Author Report Share Posted August 25, 2007 Thanks Leo, you are right. I disconnected the negative battery terminal a few times to reset it before when it first started doing this. Will make sure and remember after replacing the sensor to also disconnect the terminal for a few minutes again. Quote Link to comment Share on other sites More sharing options...
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