I can not get a code readout to display

If have to fix the problem for it to go off.

Take your truck to your local auto parts store or repair garage, and have them attach an ODB code reader to your truck to readout the error codes and reset the SERVICE ENGINE light.
Please note that the SERVICE ENGINE light only comes on when SOMETHING IS WRONG. If you do not want it to come back on, you will need to establish where the failure is and fix it.

CHECK AIR FILTER ,AND HOUSING FOR LEAKS ,ALSO HAVE SOMEONE HOOK A HANDHELD SCANNER AND READ SERVICE CODES .
COULD BE EGR PROBLEM , AIR LEAK ,VACUMN LEAK ,LEAKY INJECTOR , ETC
CLOGGED AIR FILTER
AIR FILTER NOT SEATED RIGHT IN HOUSING

replace the outlet fuse in the under hood fusebox its towards the firewall side of the box

if your car was made before 1996 yes you can, but car 96 to todays car you can not.

Hi

You don't say if the car is running or not. Are you able to start it? If not check your battery, a low battery will give this problem along with the inability to move it into gear(automatic)

If it is running the engine management light should also be illuminated, you need to get the code read to go any further with this. Bit of a problem if you don't have a code reader (you can pick them up cheep on EBay) You may also be able to get the code display using the cars 'hidden diagnostics' see http://www.bluejag.co.uk there is a readout of the current fault code that can be found as you step though the diagnostics.

Hope this helps some.

'Check Engine' is a general warning light telling you there is a problem somewhere on the engine. **Note** It is supposed to come on when you turn the key as it is checking the engine electronics. It should go off after a couple of seconds to show the system is working properly. If it stays on get a good auto electrician to plug it into a specialist diagnostic computer to find out where the problem is.

Hi, you will need a obd-1 code reader connected to the PC to find out what the code is. Here is your best bet and will save you $$$. Drop by a Auto-Zone parts store, and they will bring there meter out, plug it into your PC, and run it through for free. It will tell what brought the light on and can be erased if its not a hard code but a soft one will. It may just be a emission problem. They will give you a long readout from there computer inside that lists most all codes for this GMC, so you no what is going on and need to do. I have done this 2 times on my Chevy truck! Works great for free!! Please rate me as I know you will be kind. This will solve your problem.
Sincerely,
Shastalaker7

Any cleaning or modification in air fuel mixture valves/ and sensors can modify their function which could trigger a false read on the ECU in the car. You will likely need to have someone with a code reader plug in under dash to reset the lights and give you a readout

Two most common problems for this are the DIC and the fuel pump. Can also be the CPS. First check the code. You can try this first before going to a code reader: 1.With the car already off, switch on the ignition without starting the engine. 2. After approx. 6 seconds, the 'Check Engine' light goes out for an instant before lighting up again for 3 seconds. This 3 second flash is a warning that the actual flashing code is about to start. 3. The flashing code consists of a number of short flashes lasting 0.4 seconds. The 'Check Engine' light goes out for 2 seconds between each new flashing code (if there is more than one fault). 4. After the last flashing code, the 'Check Engine' light goes out for 3 seconds before lighting up again for 3 seconds, after which the flashing codes are repeated. Readout continues in this way as many times as you wish. Number of flashes / Function 2 / Manifold absolute pressure sensor 3 / Temperature sensor, manifold 4 / Temperature sensor, coolant 5 / Throttle position sensor 6 / Oxygen sensor 7 / Adaptation 8 / Purge valve (EVAP valve) 9 / ECM, internal fault If no flashing codes display, the problem is something else (other than those nine listed above) and must be determined using a generic code reader that supports OBD 1, or using the GM/Saab Tech II code reader and programmer. My money is on the DIC as it is a very common failure component and fuel pump failures rarely throw a code. The DICs are good generally to 100,000 to 150,000 miles, but this varies wildly, especially if the car is run with overgapped plugs for any length of time. The plug gap should be 1 mm and no more. Cars that are scrupulously maintained vis-a-vis the plug gapping can see DICs last over 200,000 miles.