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Possible ECU problem? I’m clueless, maybe you can help..


InsuredByBeretta
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Hey! I can manage the basics of a vehicle but this is beyond me..

 

So starting Monday, I went to start my 2016 Silverado using the fob and nothing was happening. Great, I’m thinking the battery is dead somehow even though I just replaced it less than a year ago. So I go out and start it with the key. The screen flashed and said “2 keys programmed”. I thought that was strange but everything worked normally on the way to work and on the way home, so I thought it was just a weird fluke.

 

Tuesday was fine…Wednesday I had to start the car with the key again. Everything was fine after that.

 

Thursday, I had to start it with the key and everything was fine on the way to work. On the way home, my truck was possessed. Lights flickering, AC shutting down or dying way down, a handful of times the truck just died on the highway..like shut down - no lights, no power steering, music, everything shut down - then it would pick back up again by itself after a second.

 

I got it home, popped the hood and checked the battery terminals..everything was clean and tight. Started it up again and it said “engine power is reduced” on the dash. I wanted to go for a quick test drive to see what that meant, but upon shifting into reverse, I had no throttle response whatsoever.. it didn’t even register the pedal being pressed.

 

Now I’m nervous, so I run inside and start googling. I saw a few people with similar problems and others telling them to get their ECU reflashed. I ran outside one more time just to test things out, and this time the “engine power is reduced” message didn’t pop up, and the throttle worked just fine..but I didn’t want to risk taking it for a drive so I left it be for now.


Anyone have any clues? Sorry if there is already a post on this, I have no idea what to search because this seems so involved.

 

Thanks!

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Posted (edited)

Usually limp mode will happen due to a problem with the throttle body. If the pedal sensor and T/B don't like what they're seeing, it immediately goes into limp mode to avoid a potential full throttle situation when your foot isn't on the pedal.

 

Best thing to do is scan and report back codes present. That will give some direction.

 

If I were a bettin' man, I'd say you've had a power or ground failure to one or more modules, and/or a communication failure on one of the networks. Could be due to mouse-chewed wires, chaffed, or burnt wires, or corroded connections.

Edited by Jsdirt
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29 minutes ago, Snowcamo said:

Sounds like someone programmed a key to come back and drive off with your truck. 

Is this really a possible cause of all of the other problems that I’m having, or is this just in reference to the “2 keys programmed” alert? I have wireless carplay and it displays my phone type before it connects, and I noticed that it has a second phone that is saved in the now. I figured it just picked someone up while I was sitting in traffic but now you got me nervous.

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20 minutes ago, Jsdirt said:

 

Usually limp mode will happen due to a problem with the throttle body. If the pedal sensor and T/B don't like what they're seeing, it immediately goes into limp mode to avoid a potential full throttle situation when your foot isn't on the pedal.

 

Best thing to do is scan and report back codes present. That will give some direction.

 

If I were a bettin' man, I'd say you've had a power or ground failure to one or more modules, and/or a communication failure on one of the networks. Could be due to mouse-chewed wires, chaffed, or burnt wires, or corroded connections.

 


Thanks for the reply.. does limp mode usually shut everything down for a second as you’re driving? 
 

Any idea what an average shop might charge to check this out? I don’t think it’s something I can tackle myself over a weekend unfortunately..

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Posted (edited)

No - limp mode could be a symptom of another problem. Limp mode only reduces engine power - it will NEVER cut off system power. You could have 2 or more separate issues happening, or it all could be related to one bad circuit. Intermittent issues are a nightmare to diagnose.

 

Most shops around here are well north of $100, so plan on that as an absolute minimum.

 

Whatever you do, DO NOT go to ANY dealership.

Edited by Jsdirt
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1 hour ago, InsuredByBeretta said:

Is this really a possible cause of all of the other problems that I’m having, or is this just in reference to the “2 keys programmed” alert? I have wireless carplay and it displays my phone type before it connects, and I noticed that it has a second phone that is saved in the now. I figured it just picked someone up while I was sitting in traffic but now you got me nervous.

Call the second phone, see who answers.

 

Have you had the truck in for service recently? Any time away from you when someone could have paired up a second phone?

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2 hours ago, InsuredByBeretta said:

Is this really a possible cause of all of the other problems that I’m having, or is this just in reference to the “2 keys programmed” alert? I have wireless carplay and it displays my phone type before it connects, and I noticed that it has a second phone that is saved in the now. I figured it just picked someone up while I was sitting in traffic but now you got me nervous.

 It may be a possibility. But I don't know about the whole somebody else's phone being on your Bluetooth set up now is just crazy. Now you got me worried for you

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