TravisK

You Cooling fans being commanded to 10-11% but completely stopping instead. The fans seems to work fine when commanded 15-90%. Happens when ac FINALLY gets nice and cool and blower turned down to 10-40%.. at idle or on freeway. And simply increasing blower speed doesn't increase commanded fan speed after they have stopped. Only acceleration in drive or popping the gas pedal will bring commanded request for fans above 10% after they have shutoff. And of course when the fans are off and the AC is on and at idle vent temperatures immediately begin to increase. Without air flowing across the condenser the AC might as well not even be on. How do I go about diagnosing whether it's the fan module? or the fans motors themselves?

Just wanted to update if anyone cared. After immediately returning to the shop after the transmission repair/replacement because of rough idle / misfire issues along with ac issues that mysteriously developed while in the shop for transmission replacement not to mention the dead battery from a roku device being left plugged in that they diagnosed as a bad battery because they couldn't simply jump it with their jump box (another $300 + fees).. I ended up pulling it out out to try and resolve the misfire issue myself after they were unwilling to stand by any diagnosis of the rough idle (basically wanting to throw parts at it until it was fixed, something I could do much cheaper on my own. The fix ended up being plugs and wires which was actually overdue) and also after the shop had it two weeks working on the ac issue which they diagnosed as a leaking compressor to evap line and bad compressor which they billed and replaced (over $2k in repairs, little more than half covered by warranty services) with the ac STILL ONLY blowing vent temps of 60+ degrees and only on the highway. Taking it back today to let them take another stab at the a/c. Service rep knew it wasn't working right when he turned it loose knowing it was coming back even tho on the paperwork says it is. Looks like they're trying to cover themselves from a misdiagnosis on the a/c. See what happens. Wish someone from gm would actually look into this fiasco of a repair. 10k+ and two months later my truck still isn't right.

Ya, in dropped it back off there about 2 hrs after I picked it up. Ofcouse my service rep went home early for the day. And the guy I dropped it off with seemed kind of annoyed I was dropping it off before the relearn process had a chance to relearn. He was trying to say 500 miles. I told him it wasn't running like crap on the highway when I dropped it off and I never had the check engine light come on before even with the stalling issues I was having that they diagnosed as a transmission problem. Guy said it would be Monday before my service rep got back and that would be the earliest they could look at it. Aggravates the piss out me that they didn't test drive it before saying it was ready. Can just already hear em trying to convince me its just part of the relearn process or that it's just a total coincidence that I'm starting to experience a totally different can of worms problem after they fixed my other one..

update and other issues now. Shop I bought it at ended up paying a Chevrolet dealership to diagnose and repair the issues. which ended up in a complete transmission replacement. Went to pick it up today. Drove it across the metroplex about 150 miles. On the way back we had stopped to look at our old apartment and noticed it kinda sputtering a little when i stopped in gear. Was thinking oh great that didn't fix the issue altho it never stalled and felt different than it was doing before... started and stopped a few times still sputtering. Hesitated to take off initially. Started and stopped a few more times, put it in park and it was still sputtering. Then the check engine light popped on with cylinder 4 misfire p0304 code. After i took off and got back on the highway and the code went away shortly after but it still felt like it was missing or the transmission was being kinda herky jerky especially when letting off the gas then reapplying slightly. I understand they have to relearn but I was thinking that was just for shift points (definitely wasn't shifting 100% correctly, however I'm attributing that to the relearn). Would a new transmission be causing the misfire or the jerkiness? Is that something the relearn process would also clean up? Never had the check engine light come on since i bought it. Find it very odd that it comes on right after a transmission is put in it.

Wouldnt just pulling the line off at the purge valve at the engine tell me if that's the issue if it continues to stall? Is that how the supposed extra fuel is getting to the engine through the EVAP system? If so then that's not the issue because it continues to stall in the same manner.

I do fill the tank, but not keep pumping it untill its absolutely full. usually after the nozzle kicks off the first time I stop. one thing I have noticed is that the cap is super duper tight when I get ready to put gas in, like as in there would be no way my old lady could put any gas in it if she had too. And I only ever just do a one click tightening. When you say the canister is saturated you mean i should be able to pull it off and dump fuel out of it?

Correct, about 115k. Throttle body actually looks kinda new and I have already done a cleaning. Dirty TB really cause such a intermittent issue? Was thinking more on the electronics side. Possible failing throttle position sensor. Only seems to start acting up after reaching operating temp. Jumped in it this morning was going to run it to the dealership and ofcouse it's not doing it now... Just trying the narrow it down, and hopefully eliminate the likelihood of a failing transmission. Would a throttle body issue really cause transmission slippage, not downshifting or upshifting correctly and not fully engaging gears or delayed engagement? Also forgot to mention that I bought it at a dealership over a month ago. Tried taking it back up there to have it diagnosed the morning after it was continually happening and ofcouse they couldn't diagnosing since it wasn't still happening. Don't know the full history on it and the new looking throttle body makes me think someone at some point thought that might be the issue as well.

2015 Silverado 5.3l 6 speed transmission stalling issue. Was intermittent. Once every few days when coming to a stop it would randomly stall. Twice now, one night about a month ago then again today its continuous and replicate-able . After further testing. And no codes being thrown. I've notice if I put it into manual and only let it shift to 2nd I can stop and go without a stall. After coming to a stop without a stall if I shift it to allow 3rd gear it will clunk like it just shifted into 3rd even at a complete stop and begin to either shutter and sputter or go ahead and just stall completely. Also noticed if I ever so slightly keep my foot on the accelerator while coming to a stop the stalling issue doesn't happen, and after comming to a stop i can take my foot off the accelerator and continue normally. Also I had pulled the battery cable hoping to reset whatever was causing it and had actually made it worse where the transmission was completely slipping and would barely allow the truck to go, seemed like it would begin working normal at higher rpms.. After driving at highway speeds I think that may have worked its self out. Still continues to die when stopping.