I have a 2015 Yukon XL 1500 SLT and looking for some knowledge here. So my thermostat fan has been running when I turn car off for about a month now on and off. so a few days ago I was driving and stopped at a red light as it turned green I started driving and noticed the dash lights started flickering a bit and I started getting random codes popping up "Power steering drive with care" "Airbag" "Stabili track, "etc." like 6 of them all at once the battery light came on and the steering wheel became stiff and I pulled into a busy apartment entrance and lost all power steering to where I couldn't move it at all. After about say 10 mins I lost power completely. I tried to jump it with a portable jumper and it started for 5 seconds and power steering failed and it went dark and stopped. I decided to undue the battery for about 20 mins and reconnect it and everything went back to normal to drive it home. That seemed to work for a few days, now the fan has now kicked back on after car is off and engine light is on again so I'm trying to get an idea as to what is causing this, Also the battery was replaced during the summer and I replaced the alternator about 2 weeks ago the thermostat and sensor however was replaced about 3 years ago but I wouldn't think that would had shut it down and gave those codes and power steering but idk please let me know if you know what's going on
2015 Yukon XL
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Joseph Garcia
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Welcome to the Forum from NH.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
Funky behavior of electrical systems are often associated with poor or failing electrical connections. First, I would check the battery cables very closely for corrosion (they corrode on the inside, under the insulation), and then check all of the grounds in the engine bay to ensure that they are clean and tight.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
Funky behavior of electrical systems are often associated with poor or failing electrical connections. First, I would check the battery cables very closely for corrosion (they corrode on the inside, under the insulation), and then check all of the grounds in the engine bay to ensure that they are clean and tight.
The fan running after shutoff is 100% due to the thermostat. These thermostats are known to fail over time, but are very sneaky in how it shows symptoms. The engine light is likely a "coolant temp below threshold".
Replace the thermostat with a GM genuine part, and I would also replace the coolant temp sensor as well while you're there (also use GM genuine part for it.) Once these parts are replaced, clear the codes, and all should be smooth sailing.
Welcome to this great forum.
tom3
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If you have a multimeter/voltmeter look for voltage drop through the battery cables. Or, next time this happens get out and give each cable a good twist at the ends, see if you get any response. I'd rather find the problem at home though.
Been there a time or two. Did you have any luck??
Of the times I've had this happen in GM vehicles it was the battery cables. As many in here have mentioned - start there. You're dealing with a sudden voltage drop and this is how the BCM responds. If both battery cables are securely connected, follow both the hot and ground leads and check their sheathing for damage. Squirrels and mice can wreak havoc on these in no time. Next you'll want to check all the ground points by unscrewing them from the frame - sand, re-seat, and seal them back up. My 2015 has rust accumulating on some of the common grounds like the one just under the drivers side door frame location. Let us know what you find.
Of the times I've had this happen in GM vehicles it was the battery cables. As many in here have mentioned - start there. You're dealing with a sudden voltage drop and this is how the BCM responds. If both battery cables are securely connected, follow both the hot and ground leads and check their sheathing for damage. Squirrels and mice can wreak havoc on these in no time. Next you'll want to check all the ground points by unscrewing them from the frame - sand, re-seat, and seal them back up. My 2015 has rust accumulating on some of the common grounds like the one just under the drivers side door frame location. Let us know what you find.
With all that’s been said, I would check the dipstick on the transmission fluid to see if there’s any metal shavings. When your fan kicks on I would replace the sensor and if your temperature gauge doesn’t go to the middle, then go for the thermostat. I used AutoZone replacement parts and they work just fine.
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