Silverado Stalls But Won't Read Out Computer Codes

2004 Chevy Silverado.
New tires no engine work. Tried disconnecting battery. 2004 chevy Silverado 5.3 v8 starts and immediately stalls. When given gas doesn't even turn over. Radio wont work but all dash lights work. Diagnostic tool wont read anything. But truck reads unknown driver.

We tried disconnecting battery did nothing. Please help. I wish I could donate but i just spent my last 11 dollars on gas so i could get friend with broken truck to work. This info is detailed enough because its all the info he gave me. But if you need more just ask and i'll ask him.

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Answer:
All these things may be related, or not. Be sure to check that the battery cable are tight. For the scan tool not powering up, check the cigar lighter fuse. That fuse iIs either in the underhood fuse block, or the drivers side dash fuse block. This fuse powers the diagnostic connector under the dash.

In fact, be sure to check all fuses. Starting then stalling could be a security system problem. The security / theft light would come on the dash after trying to start it, then the truck stall. A common problem for that on your Chevy Silverado is the theft system sensor in the steering column. This is what reads the key. After replacement a theft / security relearn procedure would need to be done to get your truck to start.

Fuel pressure is another thing to check. Fuel pressure when cranking must be at least 55 PSI. If it is even a few pounds less, your truck wont start or will start them Immediately stall out. A weak fuel pump is almost always the cause for this. There is no fuel filter on this truck that can be replaced. Removing the fuel tank would be needed to get to the fuel pump and replace it. Not a good job for you in your garage.

As you can see, this problem requires some diagnostics of these different systems to see if all are related or not.

Question:
I have a knocking sound that repeats about 2 times every minute when the defroster is on and the fan is running but no other time. It happens all the time. 2007 Chevrolet Silverado 1500.

Answer:
There are two possible common causes for this ticking noise on your Silverado. 
1. That is the sound of the A/C compressor kicking on and off. The compressor runs when you have the defroster going, as well as when the air is on. This is a normal condition and nothing to worry about. If the noise seems odd, or unusually loud, you could have a compressor that is going bad or about to lock up. Could also just be that the freon charge is low and the so the system kicks on and off. Check the belt too, on your vehicle there is a separate drive belt that turns the compressor. Probably normal, but get it checked out if it seems like something is wrong.

2. If the noise seems to be coming from the dash area, then you have a bad temperature door motor actuator or mode door actuator. These control the temp of air through the vents and location of the air- either vents, floor or defroster. When a door actuator goes bad, it cannot find the proper location it is trying to open the door to, so it goes from stop to stop and continues to move and try and find correct location. Since it cant it gives a ticking noise.

Replacing the door actuator is the only fix for this. It is not an easy job laying on the floor and removing dash panels, so i would suggest a mechanic for this repair.


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