Check engine light is on and heard a buzzing noise coming from under the truck

Tiny
JOLIE82
  • MEMBER
  • 2009 GMC CANYON
  • 55,418 MILES
I have a 2009 gmc canyon and a few days ago the check engine light came on and I changed the gas cap and turned off the check engine light. The light stayed off for 2 days and now is back on but the truck runs fine. I did notice I am now hearing a buzzing noise coming from under the truck. Anyone have any ideas what it may be?
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Monday, July 8th, 2013 AT 8:59 AM

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Tiny
CARADIODOC
  • EXPERT
You're the one standing by the truck and able to hear where the noise is coming from. We should be asking you these questions. If you can't locate the area the noise is coming from, start by having the diagnostic fault code(s) read. Those will give you an idea of which circuit or system needs further diagnosis. Many auto parts stores will read them for you for free.
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Monday, July 8th, 2013 AT 9:36 AM
Tiny
JOLIE82
  • MEMBER
Underneath the passenger side rear tire is where the noise is coming from
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Monday, July 8th, 2013 AT 10:37 AM
Tiny
CARADIODOC
  • EXPERT
That could be an automatic load-leveling pump, if your truck has that option. An emissions system leak detection device being run by the Engine Computer. You could be hearing the fuel pump. GM truck pumps are generally pretty noisy and easy to hear. That by itself is not cause for concern. The Check Engine light is telling you the computer detected a problem and it set a diagnostic fault code. You need to have the codes read to find out what the computer is trying to tell you.
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Monday, July 8th, 2013 AT 10:59 AM
Tiny
JOLIE82
  • MEMBER
Thank you so much
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Monday, July 8th, 2013 AT 11:01 AM
Tiny
JOLIE82
  • MEMBER
Ok so I took it advanced auto and this is what they have me Code U0109: Lost Communication With Fuel Pump Control Module. What I'm wondering is what exactly does that mean? Do I have replace the fuel pump? Or could it be something a little less expensive to fix. The truck is still running fine but I am concerned and wanting to fix it but was hoping I could do it myself. Any help?
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Tuesday, July 9th, 2013 AT 6:17 PM
Tiny
CARADIODOC
  • EXPERT
That's a new one for me. In the past the fuel pump and fuel supply system was never monitored or had computer controls. That was one of the few things they hadn't yet hung an unnecessary, unreliable computer onto.

I don't have access to "U" codes and I can't tell you how that code would be diagnosed. Typically your mechanic would use a scanner to talk back and forth with the various computers and make them do things so he can test their operation. A non-communicating code such as this suggests the problem is with the computer controller and not the pump itself. You've already figured that out because the pump must be working if the engine is running fine.
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Tuesday, July 9th, 2013 AT 7:25 PM

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