No start

Daniel Owner/Technician Tonawanda, New York Posted   Latest  
Question
Driveability
2014 GMC Acadia Denali 3.6L (D LLT) 6-spd (6T75)—1GKKRTKD9EJ183971
No Crank / No Start
Security Theft / No Start
No Communication

So I’ve been working on this GMC for a few days and I’m getting at the end of my rope. Towed in. No crank no start. Had new battery recently. battery dead. Large draw on battery to point will kill it in one day. Theft light on, no comm with SRS, tpms, blind Spot module. front door power windows unopened, no power locks. No comm with RCDL module. Checked ignitin switch operatin, ok. Replace BCM. No change. Fuse block behind glove box I have no power at the 3-2amp fuses. One powers ignition switch. But have power on that wire. Idk why. 3 screen shots of comm buss 1st is koeo, 2nd is key off engine off. 3rd is BCM unplugged. Feel like there’s something pulling down this whole network. found 1 tsb on the comm line from rcdl module punched in rear room, but not my issue. Been traci g powers out to modules and they have proper power. Haven’t dug out the air bag module yet, as I feel I don’t completely understand my communication scope patterns. Just looking for a little insight. Thanks 

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Tyler Technician
Hammonds Plains , Nova Scotia
Tyler Default
   

Did you check low speed can at pin 1 of dlc?

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Edward Owner
San Antonio, Texas
Edward Default
 

Hello Daniel Have you check the Left kick panel splice pack JX205 and Splice pack jx405 on left D Pillar....

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Daniel, How I would approach this. DTC check for all modules. Which ones communicate, which ones have coded, U codes? Your scope captures are from the High Speed GMLAN DLC terminals 6 - 14. This appears to be normal. Your problem appears to be on the Low Speed GMLAN. Going to terminal 1 at the DLC what voltage do you see? Is it fixed, or changing. I realize a lot of people use a lab…

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

All the modules that you have no comm with are on the Low Speed LAN on pin 1 of the DLC. You are testing the CAN network on pin 6 and 14. It looks fine in your waveform. Low Speed LAN is a single wire 0-5 volt square wave network on pin 1 of the DLC. Need to check the waveform on pin 1. More than likely the blind spot modules in the rear bumper are full of corrosion pulling down the network…

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George Diagnostician
Burnaby, British Columbia
George Default
 

I am I missing something your high speed can only has amplitude of 1 volt it should be high 2.5 to 3.5 low 2.5 to 1.5

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

I think there is something wrong with the ground lead or scope setup. That pattern looks good an he says nothing about having a comm issue with high speed modules so I assumed there was nothing with High Speed although I also saw what your talking about. Maybe that is a question we should ask.

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Paul Mechanic
Harvey, Illinois
Paul Default
 

That's what I saw also, but assume he wasn't grounded correctly.

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

I think the scope is set to AC coupling. I can’t see an icon on the screen to say. A loose ground would be very noisy and floating around on the screen.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Boom! I think you nailed it Steve. That would make sense.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Daniel can you comm with everything on High Speed CAN??

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George Diagnostician
Burnaby, British Columbia
George Default
 

I think it's his scope set up if you look closely last picture can high is zeroed correctly

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Daniel Owner/Technician
Tonawanda, New York
Daniel Default
 

did have comm on high speed, I did not scope low speed as to where I found my problem

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Todd Owner/Technician
Oklahoma City, Oklahoma
Todd Default
 

Hey Daniel, I posted a case study on the other network regarding the object detection module. In a nutshell the master module located under the bumper in the left rear of the vehicle and has no protection from anything kicked up from the tire. In my case the module was full of water from recent rains and was killing the low speed data line. If my memory serves me I was able to pull fuse #28…

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Daniel Owner/Technician
Tonawanda, New York
Daniel Update
 

ok what I failed to do here was check the low speed network. low speed was completely gone, I had replaced both rear side object modules in rear 2 years ago. turns out the left one was shorted and did in fact pull the whole low speed down on pin 1. unplugged and vehicle started. still had no drivers door module functions, replaced left rear module, programmed and all is good except for still had…

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Daniel: I can't speak for Snappy since I generally don't use their equipment. The GM tools show you pin communication for each module. Even if only one module is communicating, you know for a fact that the network cannot be shorted, high or low. If it was shorted, no modules would communicate on that network. This is something that I point out when I conduct training on the equipment. I…

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