2007 Silverado 1500 4.8l
Good battery, alternator, starter. Problem just started last week. 1.Check engine light (code P0332 & p0449). 2. Random engine knocking (sounds like rod knock) 3. Random no-start ( trys kicks back, trys then starts) . 4. Dash lights Random on -off, same with ABS light. 5. Once started with no problem but no power brakes, shut off back on fixed it. Other days runs without any issues. Replaced knock sensors year ago. Any ideas on where I should start diagnosis would be appreciated, thanks for any ideas.

 

EVAP system vent valve solenoid is malfunctioning. Also sounds like you have an issue with a knock sensor.

 

> It only blows on setting 3 and not at all for the Defroster

? is the defroster supposed to blow cold ? i don't think so.

All cars have a problem when you adjust temperature setting there's a swinging door between cooler and heater. on older GM they are plastic gears and can get jammed. Insure you can hear the door moving. you can even (remove plastic) and look in and see if the door is moving. or just look at the mechanism with a mirror to see if it appears to be rotating and moving the door within.

 

> something is draining my battery

ok you might "think the fuel pump has a ground problem or poor connection". but very possibly the drain is from something else.

however. you can check for "parasitic drain" (google it) with a cheap multimeter.

the fuse box is a very powerful tool here. if you have no idea where the leak/drain is coming from. you can isolate circuits by pulling fuses.

one famous drain is people using cigarette lighters to charge his/her cell phone. DON'T. they go bad and cause shorts frequently on old trucks and cars. also i was a certified dealer diagnostic person. people with bad alternators or batteries and problems often have been charging their phone when car is off. your car really wasn't build for doing anything other than running itself when on. (ie, even upgrading to a loud radio would be hard on the system)

 

i guess there are thousands of tips. so you'd have to be more specific about what you've tested and how.

your fuel pump should not "click off" and i'm unsure how you determined that it is doing so. I'd like to hear more about that.

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if the AC goes off frequently it's highly likely you are low on freon. the "right thing" is not to put in more freon until finding and repairing the leak. (however slow leaks (ie, old seals and long time since ac service) can be difficult and even unworth of chasing down)

 

the knock sensor may not be plugged in well. check the connector. unplug (without breaking, watch a youtube first). plug back in. it may use grounding so the engine ground might need to be good in order for the sensor to work right.

GROUNDING: all cars and chevy, as they age, need their grouds cleaned. you can google a chart. but look in engine compartment: if you see braided flat chord no insultation it's s ground strap. undo it. clean the rust off bolt and washer, put it back on snug.

! GROUNDING: between the cab and bed there is a ground connector. it always goes bad and needs to not be bad (ie for your fuel system too). definitely check that one. it's probably visible and accesible from the driver's side.

 

I am sorry i looked up P0455 wrong. that's a gross "evap leak" NOT fuel leak.

that's more like "gas cap off, hose not attached or solenoid vent door in cannister is open" (note chevy's vent door isn't in the cannister - these google'd suggestions are to be looked at with great skepticism)

NOT "carbon cannister is in-efficient so replace it" (NO, and chinese part, expensive, avoid that)

it may be cheapest to have a shop find the leak for you (diag fee $100) and do the work yourself. they can be hard to find. although if it really is a gross leak it should be easy to find.

ALSO CHECK YOUR LOCAL STATE INSPECTION. In my state not all EVAP codes fail inspection - check if your code passes emissions inspection in your locality. (this means you wouldn't pay through the teeth to get it fixed and do it on the back burner not go out of your way to get it done)

 

ah again! best advice last. i assume you'd already done this.

always insure you have 12V off +charging volts RUNNING (youtube how to check it)

if you don't your car can do strange things and will also throw "fake trouble codes" and even run rough.

cars that have an ECM can do really strange things if your battery isn't straight. diagnosticians always do that first on any repair.