Well, I am at my breaking point. I am working on an 03 Silverado 4.8L (BONE STOCK) 90K. The truck will not fire. F Pump and F pressure is fine, all fuses are fine, the battery is fine. The truck will turn over just fine, the injectors will spit fine however I don't think I have spark. The motor will not even cough.

Here is what I did work on: I pulled the fuse lid under the hood and found a bunch of sunflower seeds (mouse activity). The seed shells seemed to be there for some time. I also noted several chewed wires of which none were all the way through so I used liquid electrical tape and patched the insulation. I removed the entire wire harness / PCM and fuse block and looked over each wire. Several more were chewed so I patched them. Buttoned it all back up and still nothing (will turn over fine, just not fire,...not even a hick-up.

Any suggestions? I am going to fire up the laptop soon and run some logs (HPTuners). Any tips on what parameters to look at?

 

do you have a crank signal?

 

yes I do.

 

is the signal getting to the computer? make sure all your fuses are good. is the security light on?

 

I scanned the crank signal off the PCM. Nope the security light is not on,...I wish it was, then all I need is a half hours time to do the relearn. I'll mess with it tomorrow....

 

I dont doubt you already thought of this but are all the grounds good. I have seen grounds cause the same issue.

 

power for spark is from two thin pink wires. one is for bank 1 other is for bank 2. makes sure you have power to there. the coils get power viva a wire from pcm and then of course a 12v reference

 

check your ground at the pass side head/block...its a single black wire that goes into the main harness and seems to be a "mouse attraction" those guys love that wire and I've seen it cause allllll kinds of wierd problems

 

Well, started to go under the truck. It was getting dark out so I really couldn't get into it too much. HOWEVER, can someone identify the chewed off wire in the pictures? The first pic is from a good distance away so you can get your location. Second picture is a closer shot with a flashlight shining on it. Have good reason to believe this is related to a root cause. You are looking in to the engine from the front of the truck from the driver's side tire. The plastic shield is really in the way and I didn't have the time to remove it and look into this further. Curious to see if someone has some insite before I rip into it on sunday. Again, this isn't my SSS just a ECSB 4.8L.

 

It's the ignition switch. We replaced 37 of these in 2006. It's more common than you think. You're trying to think way too technical.