sefiroxx

Sensors in front of the cat should cycle positive to negative - reflecting what the computer is doing to adjust injector opening time (more fuel/less fuel) Sensors behind will usually be stable and indicative of cat efficiency (gradual change of signal indicating slow consumption of cat metals). If the front sensor are cycling, good but if not around 0 then they may be corroded or the engine needs work.

Many kinds of shorts, many kinds of symptoms - only one of which is blowing the fuse. Other symptoms include slow drain, incorrect voltage signals, interfere with neighboring circuits . . .

Shameless link to parts diagram: https://www.wittrans.com/parts?type=4L60E

Look at the Legend at bottom. You'll see O2A and O2B marked as 3 and 4. Find 3 and 4 on the map.

On my 04 Sierra, one fuse - O2B

Flex fuel required changes to the fuel system to support alcohol. So fuel tank, lines etc where I upgrade to remove rubber etc. Nearly all engines will support e10,e15. However, if you are trying to run E85, you need an engine raged for such. The engine will support higher compression to needed for the lower btu fuel.

Front seal or torque convertor

Pull code Does it crank? Symptoms change if you are in the truck and remote start?

When researching cat replacements, be careful of cheaper cats as they likely have less palladium/rhodium on the coating. Also, no guarantees, but consider if the mfg provides a California version of the cat. CA requires an extended warranty period. A cat would have to be better constructed and more metals to withstand lumber period. For some mfg, they use the same cat as other 49 states, but charge more in order to backfill the insurance to cover the replacement. They would have to have confidence in the product to warranty it in CA.

Have a 01 suburban 4x4. Bought new. Now at 345k. 4x4 only used .5% and usually for something big effort short term (pulling a cat out, pulling tree stump, driving in rare snow) - front diff replaced at 1 year, warranty - Tranny replaced at 160k. Parking pawl broke - motor replaced at 310k. Son forgot to monitor oil pressure and kept driving. Lots of seepage leaks prior to replacement (I was about to embark on a reseal project before motor went) - Have replaced fuel pump (2x), alternator (2x), starter, compressor, radiator (2x), condensor, heater hoses. Last items on the to do list as they are leaking: per steering pump, rear diff cover, rear shox. Texas driven, no rust. Lots of dings, scrapes, tires, brake pads, oil etc

Everything metric , Cadillac 92, 95, 02, Chevy 01, 04. I've been upgrading my metric tools for a decade

Need to pull codes for exact cause. Likely though, some moisture got in around soak plug wires or other sensor wire and caused solve short term short until it fried out.

I have swivel and wobble extensions that I use all the time. They get me 45 and 5-10 degree angles. Highly recommend them along with 1.5, 3, etc extensions

Condensate drain (from the interior) exits the firewall and turns down to drip. You could tube routing problems or the tube is missing

I run Cooper Discoverer HTP, great stopping power, very good rain, ok on trail. I bought a no brand liner from the truck store. About 3/8 thick black rubber impregnated with fiber. Still in like new condition. Heavy, but I can stl get it out to sweep out the bed.