Hi, welcome to Just Answer.
Can you tell me from the schematic below which fuse is blowing?
Do you have the 4 cylinder or the V6 engine? And how many miles are on this truck?
Thanks, XXXXX XXXXX does not have to do anything with the alternator; below is the wiring schematic for fuse 10 (20 amps) a common fuse to blow on these. Usually you have a shorted ignition coil or fuel injector. What you need to do is disconenct the ignition coil and replace the fuse, does it still blow? If so, than disconnect the injector harness connector, replace the fuse...if it doesn't blow you'll need to replace the Vortec injector assembly under the intake plemun. If the fuse continues to blow, we need to disconnect the crankshaft sensor and try again. The last component to disconnect will be the engine computer, which is a rare failure for this typw of problem, but very well can be. If after disconnecting all the componetns powered by this fuse, it still blows, than we have a shorted wire from the coil, injectors, engine computer, or the crankshaft position sensor to the fuse, and you'll need to carefully check the wires in the harness, or check continuity using an ohm meter with all the components disconnected.
Doesn't the engine stop running as well?
So what about the statement in your original questions about " the fuse blows as soon as I turn the ignition key on." Does this occur all the time? And if so, take a look at the fuse arrangement I posted earnlier and get me the correct fuse, fuse 10 is for the engine computer and related components.
Let me know when you can, if the engine runs...it is not the #10 fuse, it may be the #9, but that also supplys power to the ECM...I'll be offline from 11:30pm-2:00pm PST, if I receive a reply during that time, I get back to you after. thanks.
Thanks for the accept, but if the fuse still blowing?
Alright, that fuse powers a few different components. We either have a shorted component or a shorted wire from one of these items to the fuse. Below is the wiring schematic for fuse #4. The reason the alternator stops charging when the fuse blows is becuase the alternator circuit for the charge lamp/guage needs to be complete in order for the alternator to charge. When the fuse blows the entire instrument cluster is dead, thus affecting the charge guage/lamp as well. What we do from here is start disconencting the items in the circuit and replace the fuse each time we disconect one of the items, until the fuse no longer blows or we have disconencted every item in the circuit...Lets begin with the a/c clutch relay, since the a/c clutch is a common failure on these. Do you know where the relay is located? If no let me know.
I've posted the relay location below, let me know if your still having trouble locating it.
No problem, let me know when you can and if the fuse still blows, we'll move onto the next component.