OT: 08 GMC Sierra 1/2 ton check engine light

[Tx Jim]

Pickup that I use similar to a tractor that I handle rd bales with had check engine light come on today. Engine went into reduced power mode. Then engine wouldn't stop operating when ign switch was turned to off & check engine light stays on after ign switch is turned off then turns off after 10 or 15 seconds. I scanned codes & saw Po222 & Po455. Attempted to start engine & no start. Po222 is accelerator controller & Po455 is evap leak. My truck has a newer fuel cap. Battery tested 12.7 volts & I cleaned both battery cable ends. Still no engine start. Engine won't attempt to start with trans selector in "N" either. I'm guessing faulty wiring connection but I wondered if any member experienced similar electrical problem??
Thanks for any ideas, Jim

 

[rustred]

It is not clear what u mean by no start. Is the engine
cranking over or is it no crank situation. ?

 

[Geo-TH,In]

Gremlins in the wiring. I hate Gremlins.
I hope my 07 GMC Sierra doesn't get your gremlins..
Please keep us posted.

 

[Tx Jim]

(quoted from post at 22:46:37 04/13/23) It is not clear what u mean by no start. Is the engine
cranking over or is it no crank situation. ?

Starter will not engage flywheel ring gear. Auto trans gear selector stopped illuminating selected gear. Check engine light stays on for a few seconds after ign switch is cycled off but clearance/headlights cycle off before check engine light. Weird gremlins!

I just had rebuilt engine installed & had driven truck about 25-30 miles before this started happening. Technician(friend) that replaced engine told me he had viewed/repaired several bad wiring connections in area of engine compartment that he repaired. Technician stated he would come pick it up in a day or 2 I was just trying to locate if there's a common failure point.
Thanks for any clues.

 

[DaveBN]

P0455 shows EVAP fault. Do you smell gas fumes in the area of the fuel cap? Why was a new fuel cap installed? If your not familiar with EVAP their are some good YouTubes on that system. Also check all your ground cables.
Dave

 

[Tx Jim]

Code Po455 I'm very familiar with. I agree checking engine to chassis grounds is a good starting point. I visually checked them yesterday but the grounds need closer inspection. One of the things that stumped me when electrical gremlins 1st raised their ugly head is engine would continue operating 15-20 seconds after ign switch was placed in off position & check engine light remains illuminated for a few seconds with ign switch in off position.

 

[dhermesc]

A 16 year old truck with electrical problems. Grounds, switches, power relay etc... The part about it continuing to run after the switch was turned off might be a huge clue to someone that is
familiar with this. 2007/2008/2009 when GM was in huge financial crisis and they cut corners on part suppliers and produced a lot of products that had issues.



https://trucksauthority.com/chevy-truck-wont-shut-off/#:~:text=The%20problem%20with%20ignition%20switches%20also%20causes%20the,occur%20due%20to%20the%20inappropriate%20connection%20of%20wires.


https://www.gmtruckclub.com/threads/help-silverado-stayed-running-without-the-key-in-the-ignition-switch.77753/

Some of the people on the second link think it may have something to do with the retained power that operates the radio and lights for a while after you shut the engine off. Since you can't get it
to start you can't do the easy check by opening the door (that kills the retained power) and see if the engine shuts off immediately.

For what its worth it does not appear to be terribly uncommon given the number of people that say they have the same issue. They never post the diagnosis, but it appears to be short in the fuse box.


This one agrees - Fuse Block short


https://www.gmfullsize.com/threads/truck-wont-shut-off.288226/


With it in a no start situation right now it will probably be easiest to find if you have a mechanic that can diagnosis an issue by tracking it down as opposed to being a part swapper.

 

[BarnyardEngineering]

I drove my 2003 with a P0455 for about 9 years. I'd just reset it about a week before annual inspection. That's not the cause of your starting issue.

My 2015 had a no start issue. It turned out to be the starter.

 

[Tx Jim]

I'm aware Po455 would not keep truck engine from operating. I just wonder what the EPA thinks is suppose to capture gasoline fumes when fuel cap is removed to put gasoline in the vehicles tank?? Alternator was making noise(faulty brg) before engine decided to not operate. I pickup up alternator from repair shop late yesterday afternoon & local shade tree mechanic is coming this morning to install alternator & begin checking the electrical system.
Thank you for all replies, Jim

 

[Tx Jim]

(quoted from post at 12:00:50 04/14/23)


https://trucksauthority.com/chevy-truck-wont-shut-off/#:~:text=The%20problem%20with%20ignition%20switches%20also%20causes%20the,occur%20due%20to%20the%20inappropriate%20connection%20of%20wires

Thanks for posting links. On this forum if you click on box with URL & insert URL before/after the link then link will be easier for viewers to open
https://trucksauthority.com/chevy-t... due to the inappropriate connection of wires

This post was edited by Tx Jim on 04/15/2023 at 05:58 am.

 

[Tx Jim]

My mechanic has discovered if he pushes ign key into key socket firmly then turn key engine will start BUT engine continues to operate 10-20 seconds when key is turned to off position & key removed from socket. To my knowledge this truck doesn't have option of "remote start".