08 GMC Yukon won't start
my 08 Yukon has 92000 miles, recently its been having a problem starting. its not the battery or alternator. I had it towed to dealer said it didnt code for anything, towed it to another dealer and the problem happened there, so the dealer said they believed it to be fuel pump. I got the quote, but asked them to check the anti theft module, because of this forum, i had seen several post about the anti-theft malfunction causing truck not to start. Advisor said didnt believe it to be problem. I drove it home. day later I'm stuck again. Left truck, came back to get it about 8 hours later, it started. Same thing happened the next day, finally it wouldnt start again. so I had it towed again. Dealer says after several days, its the fuel pump for sure. Had them do the fuel pump 900 bucks, went to pick up truck, wont start......Dealer said give them a few more days. please help if anyone has had this issue.
Answers
Any luck at the dealer's?
Try skimming this discussion for ideas too:
GMC Yukon Start Stall Idle Problems
I am experiencing this exact same problem with my 2007 GMC Yukon XLT. My vehichle has 135,00 miles but has now left me stranded twice.
The first time this happened I was 400 miles from home and had to stay overnight. When I put the key in the ignition, it turns but makes no sound. All the electronics in the car work perfectly fine (radio, windows, AC, etc.) but the engine will not turn over at all. I tried to jump-start the vehicle and had a tow truck come out and try to start it. Nothing. I towed the Yukon to a local (non-dealer because the closes one was 60+ miles away) repair shop that was closed at the time. When they called me the next morning I was informed the vehicle started right up and they couldn't identify a problem. Alternator, battery, etc. all tested fine. I drove it home and everything has functioned perfectly for several weeks. Last night I tried to start the vehicle and it is dead again. Exact same symptoms.
Did you find a solution? Any suggestions?
@deptmgr57, ouch.
Sounds like they've fixed it "right" at least.
"He replaced the fuel injection module and the truck is running and starting just fine. 998 bucks total". I am not mechanical at all. Would a faulty fuel injection module keep the engine from turning over at all? My vehicle makes no sound what so ever when I turn the key in the ignition. Also, once it fails, is there any reason why it would start working again the next day like there was nothing wrong? Just trying to make sure I don't spend $998 unless I absolutely have to. Thanks for your feedback - you give me hope there is a solution.
But what I can do is explain how to test and prove what it is. Do you have a voltmeter? Can you access schematics? What about a scan tool, or has anyone pulled codes and documented what they found for you?
In the meantime, can you tell me if anything else doesn't work when the problem occurs? Things like the power windows, wipers, lights. It would really be helpful to have every module scanned for codes and document what modules responded and what codes they had in memory. Then when it happens attempt to communicate with all of the modules while it wont start and see if some of them are missing.
If you have a regular shop one of the tricks that I would often do is have the customer ready to call me the moment the car acts up and as long as they were close enough I would go to the car and start testing before it got moved. When it is a random failure it takes patience and a good game plan to solve the problem.
What is the battery voltage when the condition is present while attempting to crank the engine?
What voltage do you measure from the battery positive post to the positive cable connection of the starter when the problem is occurring?
What voltage do you measure from the battery negative post to the body of the starter when the problem is occurring?
What voltage do you measure from the positive cable connection of the starter to the solenoid output terminal when attempting to start the engine while the problem is occurring?
Kept reading forum after forum trying to find something useful, but never found someone with the same issues. Read something about the mega fusible link mounted on the firewall going bad, so I replaced that and that didn't help. Read something about corrosion around the various grounds. I checked all the ground and all looked good.
Now I would beginning to loose all hope when I found something interesting in one of the forums. It talked about communication issues among the modules and to replace the terminating resistor up above the spare tire. So got on Amazon and ordered one as well as new positive and negative battery cables. Somewhere in there I read that the ones from the factory had too high of resistance. Got all the parts and crawled under the truck and replaced the resistor. I figured I'd try one thing at a time to see what worked. Started car and drove it home. Everything was perfect. Drove like a new vehicle. I was confident that I'd finally figured it out. I drove it everyday for a month and had 0 issues. Until just the other day when I pulled into the driveway the dash went limp and lit-up like a Christmas tree. Pulled into garage and went to bed. Next morning started fine, but had check engine light on so I turned truck off and went to start and nothing. Dash lights on, radio on, a/c on. Everything seemed to be normal, but no turning over. Cycled key a few times and fired right up. Weird. Half way to office it freaked-out again. When I got to work I scanned it and found codes U0100 Lost Communication with ECM/PCM "A", P0700 Transmission Control, P069E Fuel Pump Control Module and U0073. Cleared all the codes and went to Costco to get gas. After gas went to start and same thing. Nothing. Tried about 30 or more times before it would finally start. Drove straight back to work, parked it and grabbed another vehicle.
That's where I threw-up my hands and decided to consult with the forums. PLEASE HELP thecardoc3!!!
So at this point I need to know:
Which modules set which codes. For example if the BCM, ABS, IPC, all had the U0100 code set against the PCM, but those modules dont have codes set against each other, then initial testing would be concentrating on issues that could take the PCM off of the bus all by itself.
That same exercise would be repeated for the U0073.
The P0700 just means that the TCM has codes stored in it.
The P069E is an informational code that sets during a loss of communication. At this point that would be considered normal and is a result of the problem that is causing a loss of communication.
While it won't start the first thing that I would do is attempt to communicate with the vehicle with a scan tool. I want to know if some of the modules can communicate and if so which ones.
If they dont communicate at all then I would normally use an oscilloscope and measure the CAN bus signals. They should be 2.5 volt at rest and go up 1v on pin 6 for communication and down 1 volt on pin 14.
With a voltmeter you should see approximately 2.7-2.9v on pin 6 and 2.1-2.3v on pin 14.
With only the PCM missing, either alone or with all of them down, the next thing that I would do is go to the easiest sensor that I can access under the hood. I want to measure the 5v reference to it, the ground circuit, and the signal from it. Do that, and tell me what you found.