20 Most Recent 2003 GMC Sierra 1500 - Page 3 Questions & Answers

Try a tune up

Throttle body positioning sensor could be bad or might need a toon up good luck

Crank shaft positioning sensor most times its between the motor n tranny but u can pull it from outside of the 2 look aroud where they boolt together it has 2 or 3 wires on it n it has one bolt or screw in it remove it an it slides out most times its on top n u gotta feel for it while ur under the truck n go in blind n do it all by feel best to buy it first so u know what ur looking for. It can also be ur coil if it has one not sure if that year has a coil but id try sensor first should work out good luck hope it helps u out

don't attempt any more driving get it towed or more damage could /will be done

Are there any lights lit up on your dash?? This sounds familiar ... The security system sounds like it is failing which is a very common issue in GM's. There is a module that you can get to bypass it.. you can even put the part in yourself.. read this over and see if you think it will help..

This is a bad instrument cluster. I recommend that you replace it. Don't use OEM though they are expensive.

Probably the temperature sending unit on the engine, not the dashboard.

adjust rear brakes

Headlight ground is a common problem. Also, check that the battery ground is sound, if battery ground goes to engine, check that engine strap to frame is also sound.

I have the same problem on my 2006. They say it is the blend door actuator, located above and to the right of gas pedel. I googled and watched this: http://www.sparkys-answers.com/2011/02/2003-chevrolet-silverado-changing-mode.html

Sounds like one of the blend doors is stuck or not working. Try and pinpoint the door by playing with the controls. May need to purchase a actuator, the part that powers the door to open and close,

timing belt has probably broken

2003? Likely your catalytic converter is stopped up--that's what P0420 is. Unfortunately, this is a VERY expensive repair unless you do it yourself, and then it's only expensive. You can find a Walker-brand (GM OE for years) replacement on that Amazing store web-site for about $325.00. At the Chevy store, it's going to cost you TWO THOUSAND dollars, including labor. You don't have to be a master mechanic to do this. If you know which end of a hammer to hold, I can talk you through it--it just bolts into place (hint: it's called "converter", but it's really 2 of them, pre-assembled into a Y-pipe with all 3 flanges required to bolt it in. It does require some small disassembly of other stuff).

These are usually a combination of Velcro, screws and snap latches. The screws have concealment caps that can be removed with a small screwdriver. The other place is under the rubber liner mats for the "catch all" area and in the bottom of the storage compartment itself. If you have any lighters, ashtrays or power points you will have to remove those first as well. Small screws usually hold those in.

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