'15 Yukon XL SLT will not start, cluster light going crazy, engine will not shut off

[limax]

Hello everyone,

I'm new to this forum and asking for help. This morning I could not start my '15 Yukon XL SLT. Most of the cluster lights went on/off (check engine, tpms, airbag, theft system... etc) the backlit elements would dim down and up again. Fuel gauge would jump up and down. Decided to disconnect the negative battery terminal for few minutes.... it helped, the truck stared right up without any problems. Drove it to work. At the end of the day I had the same problems so I disconnected the battery again and started it but the cluster lights were still on/off. I proceeded to drive home but the tachometer / speedometer / fuel / temp /voltage gauges would go on / off check engine light TPMS etc.... whole cluster was like a blinking christmass tree.
I made it home but could not shut the engine off (it seemed to me like the car did not know it was running because I could lock / unlock all doors with the remote) so I decided to disconnect the negative cable from the battery but it did not work. I finally shut it down by removing the ECM fuse. With this much going on I think it may be a ground wire broken some place. Any help appreciated.

Max

 

[Doubeleive]

Hello everyone,

I'm new to this forum and asking for help. This morning I could not start my '15 Yukon XL SLT. Most of the cluster lights went on/off (check engine, tpms, airbag, theft system... etc) the backlit elements would dim down and up again. Fuel gauge would jump up and down. Decided to disconnect the negative battery terminal for few minutes.... it helped, the truck stared right up without any problems. Drove it to work. At the end of the day I had the same problems so I disconnected the battery again and started it but the cluster lights were still on/off. I proceeded to drive home but the tachometer / speedometer / fuel / temp /voltage gauges would go on / off check engine light TPMS etc.... whole cluster was like a blinking christmass tree.
I made it home but could not shut the engine off (it seemed to me like the car did not know it was running because I could lock / unlock all doors with the remote) so I decided to disconnect the negative cable from the battery but it did not work. I finally shut it down by removing the ECM fuse. With this much going on I think it may be a ground wire broken some place. Any help appreciated.

Max

First suspect is your battery cables, battery, ground/s, mine turned out to be the alternator but I think it was a extremely rare case.

 

[limax]

Thanks for pointing me in some direction, today I'll inspect battery / engine bay area cables. We've had a lot of snow in NJ lately I think moisture / salt may be contributing to this malfunction.
I'll report later.

 

[zbad55]

A few days ago the wife had a similar issue, she called me all freaked out with all the lights on the dash going crazy could not start the car. I had her put the key FOB in the pocket that is in the center console. All was fine, when she got home I replaced the battery in the FOB and problem solved, maybe this is the issue, this is on a 2015 Yukon also

 

[tsuintx]

These things are known to be pretty damn finicky when it comes to proper electricity. As @Doubeleive said, start with all those and see what you can find.

Also, if you’re still running your original battery from 2015, it’s time to replace it.

 

[limax]

I just finished checking things out and it does not look good. Battery voltage is steady at 12.1 volts, it was replaced on July 2019.
Changed the battery in the key fob. Checked all the cables going to the battery, also the engine bay fuse box. Nothing seems to be out of order.
Right now when I connect the battery I just get all cluster lights once... after I push stop/start button again nothing happens, cluster stays completely dark, when I press the start / stop button all that happens is a relay click. Can't start the engine.

 

[limax]

Quick update from this morning, after all the snow we had yesterday it got really cold about 12° decided to try to start the truck it started right up without any problems. Two days ago I couldn’t even get it to run


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[SuperOldSchool]

I had this occur and it was battery cables. Replaced them under warranty.

go to autozone and have them test your battery to rule that out too.

 

[limax]

Thanks for the info. I took it to the mechanic. He's helped me with electric problems before so I hope he'll be able to sort this out.
Upon first scan he's found some fault codes in the BCM. I'll pass him the info about battery cables as well.
Will let you guys know what he finds out.

 

[limax]

I finally got my truck back, it turns out that it was a faulty side detection sensor located in the left front of the vehicle. It stopped working about a year ago but I didn’t care much for it. As a result it fried BCM module so both needed to be replaced and programmed.


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