So I have a 2015 Yukon XL Denali with the 8 speed transmission. I just finished installing the wire harness with the temp sensor, thankfully it was the two piece wire harness so I didn't have to take out the valve body. I'm pretty sure I got the connections all in the right spot. Got the oil pan reinstalled and bolted in, then added about 9 quarts of fluid until it leaked out. Was going to pull the plug after it was running for a minute and circulate through the system so it can be at the proper levels. But when I went to start it, at first the noticeable symbol was a car and lock symbol. I figured maybe it didn't like it being on the jackstands, so I took it off of them and tried to start it again, still the same issue. After several attempts, the car and lock symbol doesn't show up anymore, but it still won't start. I have had the battery disconnected for about 20-25 minutes to see if that will reset anything, but I'm at a loss. Thankfully I'm off for two more nights, but I work third shift so it's difficult to work on cars at night. Any help or advice would be very appreciated, as I cannot find much of anything online in terms of trouble shooting.
Issue starting 2015 Yukon after changing transmission wire harness
- Thread starter Mongolas
- Start date
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Do all of your accessory and vehicle external lights work? Radio work?
If so, sounds like the IMS isnt communicating with the PCM. If no comms are being received from channel N (or PCM doesnt recognize the IMS input signal) then vehicle wont start because the PCM cant confirm the trans is in Park or Neutral.
Thank you for your response. Yes, the dash cluster, headlights, internal overhead lights, as well as the screen in the center seem to work fine. Everything appears to be normal except the engine starting. Radio even kicked on after disconnecting the battery for a bit and reconnecting it. I really want to make sure it's something I did before I drop the pan again and check my connections, but I'm 99% certain I make sure everything was connected as it should be, and made sure the connections were secure. If it's a communication issue, what are my options?? I'm pretty low on funds at the moment until payday.
Also, I noticed in one video that someone made doing the same repair that they connected all the wire harness connections without cleaning it, so I followed his example. I hoped that the fluid isnt xonductive but that is currently my main concern and the reason im 99% sure I did it right and not 100% sure.
Depends on the cause...if you did everything correctly, your next step is to pull the IMS connector and begin ohming the pin sets to check for damage and see if each change from open to closed while someone else runs the shifter through the gears. If channel N doesnt respond then the IMS is bad and needs to be replaced. This ATRA webinar handout should help get you started...skip to page 41 for the Internal Mode Switch.
This is one possible cause so up to you how you want to prioritize it against testing for other causes..
Also quote my posts so I know you responded if you want me to reply back...otherwise i wont know you have replied.
So it would seem that I dont have much choice but to open it back up again and check the connections? Will I need to clean any fluid off of the connection before connecting them?
Do what you can to rule everything else out first before taking the pan off but if you're unable to do so, that's your next step. I always use CRC QD Electric cleaner on connectors but not sure it's mandatory - just my personal preference to ensure there won't be any problems...
Okay that sounds good. I have a mechanic just down the road from me that I talked to earlier. He said if he has time later this afternoon, he'll come down and scan my issue. But he also doesn't think the fluid being in contact with the connector is an issue, which was something I wondered, so my mind is more at ease, and hopefully maybe it's just a matter of resetting something. This whole debacle has definitely made me start shopping for a good scanner to diagnose my own check engine lights.
I'd absolutely get a good bi-directional scan tool...These days, you really can't be without one if you want to do any diag/troubleshooting yourself...
Look into Snap On or Autel...Autel scanners are a little less expensive for much of the same capabilities you would want to have though I think they're made in China while the SnapOns are made either here or in an allied country...
The other consideration is whether you want a stand alone bi-directional scanner or something that has both bi-directional scan as well as lab scope capabilities...A third consideration is whether you want something with WiFi...The more features you have the higher the price...
Also make sure you buy something that is still supported and upgradable by the manufacturer...Since your vehicle is fairly recent, new information and/or module updates may be developed and pushed out to end users for updating...Snap On's website has all the scan tools they currently support (I imagine Autel's does as well)...Other makers include Bosch, OTC/SPX and Innova but I don't know anything about them...
