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2003 GMC Sierra - Page 4 Questions & Answers
Pedal position malfunction
You can change the tps alone. You do not have to change the entire throttle body. It shouldn't be riveted in place, it should have screws or bolts on one side or the other. If it's riveted in place, use a dremmel and grind the rivets off. You can replace rivets with screws on the new unit.
Wiring diagram 2003 GmC Sierra
I need wiring digram for GMC 2003 SIERRA . I have the left head light working fine but the right I have no power to it. I have checked the fuses and relaysand so far have not found and broken or frayed wires.
Replacement cabin air filters
I personally own a '03 gmc 2500hd and it does not have a cabin filter to replace. Ive heard they reside in the unit under the hood and are difficult to replace. But my search has been thus far unsatisfactory.
2003 GMC Sierra is running rough. What can cause
Find the egr valve and with the engine running, disconnect the vacuum line attached to it. If the engine runs better then the egr valve is stuck open. Replace the egr valve. It is held in by 2 bolts and usually located at the front of the intake manifold. Usually dull gold in color and shaped like a mushroom.
2003 GMC Duramax Diesel won't start
I see that you had the injectors replaced 20,000 miles ago. I would still check the oil to make sure it is not overfull. The new injectors could be bad. If the oil level is not overfull then get a paper towel and touch the dip stick tip on the paper towel while oil is on the dip stick. If it's only oil it will not spread. If it has diesel in the oil the oil with spread. If this test doesn't show the injectors to be bad then you have three other possibilities. The FICM (fuel injection control module), the fuel pressure regulator, or the injection pump. It's hard to pinpoint what the problem is without running more tests and the only way to run those tests is with the computer the dealership has. Just so you know your injectors are still under warranty until 100,000 miles. Most likely you will have to take it to the dealership to get you truck fixed. I hope this helps you some.
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