2018 Yukon SLT slow start drawing too much power when engine off

[Jaxar]

Hello,

I noticed a few related threads, but non seemed to provide a good answer. I have a 2018 Yukon SLT and recently I've noticed it very slow crank (almost sounds like the battery is going dead, but fairly new battery) i plugged the meter onto the battery when engine off and it is reading 13-18 amps. I pulled every fuse one by one to see if it was something there drawing the power, but everything stayed at 13-18 amps when engine off.

I have to run a trickle on it over night for the vehicle to start the next day... sometimes will start but very slowly and feels like battery is nearly dead. Once vehicle starts everything seems normal and battery voltage at 14. I turn the vehicle off after driving 10+ minutes and very slow crank again immediately. Any suggestions ?

 

[BigBlueLB756]

Replace the positive 12v battery cable (the short one).

How To: Strange electrical issues with 14-18 Sierra/Yukon? Do this test first! - 2014 - 2019 Silverado & Sierra - GM-Trucks.com

More Information for GM GENUINE 84494554 (rockauto.com)

 

[sealandsky]

Hello,

I noticed a few related threads, but non seemed to provide a good answer. I have a 2018 Yukon SLT and recently I've noticed it very slow crank (almost sounds like the battery is going dead, but fairly new battery) i plugged the meter onto the battery when engine off and it is reading 13-18 amps. I pulled every fuse one by one to see if it was something there drawing the power, but everything stayed at 13-18 amps when engine off.

I have to run a trickle on it over night for the vehicle to start the next day... sometimes will start but very slowly and feels like battery is nearly dead. Once vehicle starts everything seems normal and battery voltage at 14. I turn the vehicle off after driving 10+ minutes and very slow crank again immediately. Any suggestions ?

Unfortunately your issue could be caused by one of a myriad of things. Last winter I had a dead battery issue as well. I'd start with a fully charged battery and within 24 hours it would be dead. I replaced the battery and same thing happened. In the end, it turned out to be caused by one of the passive unlock "buttons" on the door handle was stuck in the depressed position and that caused the drain.

 

[Tonyv__]

Hello,

I noticed a few related threads, but non seemed to provide a good answer. I have a 2018 Yukon SLT and recently I've noticed it very slow crank (almost sounds like the battery is going dead, but fairly new battery) i plugged the meter onto the battery when engine off and it is reading 13-18 amps. I pulled every fuse one by one to see if it was something there drawing the power, but everything stayed at 13-18 amps when engine off.

I have to run a trickle on it over night for the vehicle to start the next day... sometimes will start but very slowly and feels like battery is nearly dead. Once vehicle starts everything seems normal and battery voltage at 14. I turn the vehicle off after driving 10+ minutes and very slow crank again immediately. Any suggestions ?

We’re you able to get this issue resolved? Having same problem with my 15 right now

 

[Fless]

@Tonyv__ there are many good parasitic draw YouTubes, Eric O at South Main Auto has several. It's best to use the voltage drop method on the fuse test points, instead of pulling fuses; that way you're not waking up modules as you reinstall the fuses. If you need a link to the voltage drop charts tag me in a post or PM me.

I had an intermittent parasitic draw on my NBS; ended up installing a shunt inline with the negative battery cable, and put the meter where I could monitor the draw any time. At a minimum you need a meter that is rated for the next highest Amp value that your alternator puts out. I went overboard and got the 300A one because I didn't know that at the time.
https://www.amazon.com/gp/product/B0828HTM6F/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

After fixing the draw I uninstalled the shunt and now I just use the meter in the link below to occasionally monitor the draw when everything is asleep. Since it reads DC current in the mA range, the jaws allow only a 1/2" cable diameter. Not many meters can read this low, but it's perfect for my negative battery cable.

Amp Meter [Amp Clamp] Recommendations?

Specs say they're for AC current, not DC. The AC clamps are relatively cheap, and the DC ones are $$$ if you want to see below 0.1A. ya I forgot it only does ac clamping, I use it for testing a variety of things dc clamping is not one I ever have a need for though

www.tahoeyukonforum.com

 

[Tonyv__]

@Tonyv__ there are many good parasitic draw YouTubes, Eric O at South Main Auto has several. It's best to use the voltage drop method on the fuse test points, instead of pulling fuses; that way you're not waking up modules as you reinstall the fuses. If you need a link to the voltage drop charts tag me in a post or PM me.

I had an intermittent parasitic draw on my NBS; ended up installing a shunt inline with the negative battery cable, and put the meter where I could monitor the draw any time. At a minimum you need a meter that is rated for the next highest Amp value that your alternator puts out. I went overboard and got the 300A one because I didn't know that at the time.
https://www.amazon.com/gp/product/B0828HTM6F/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

After fixing the draw I uninstalled the shunt and now I just use the meter in the link below to occasionally monitor the draw when everything is asleep. Since it reads DC current in the mA range, the jaws allow only a 1/2" cable diameter. Not many meters can read this low, but it's perfect for my negative battery cable.

Amp Meter [Amp Clamp] Recommendations?

Specs say they're for AC current, not DC. The AC clamps are relatively cheap, and the DC ones are $$$ if you want to see below 0.1A. ya I forgot it only does ac clamping, I use it for testing a variety of things dc clamping is not one I ever have a need for though

www.tahoeyukonforum.com

That’s interesting. I might have to check it out that shunt . What was the cause of your intermittent draw?

im not ruling out a draw yet. But it doesn’t act like that. So the other day my truck just started slow cranking periodically. Then it slowly became every time I started the truck. Alternator seems to check out. Showing 14v on dash. 14.3 with multimeter at the battery post. So I pulled battery. Took it to autozone and they said the battery was 100%.. I went back home put the battery on a trickle charger over night. Next morning truck started fine. Dropped my daughter off. Started up fine. Stopped for gas. Fine. Drove an hour to the shore. Parked for 5 hours. Started fine. Drove an hour back home. Picked up my daughter and then had a slow start. Then again later that night slow start and this morning slow start. went with my gut and bought a new battery. Popped that in. Slow start but it also read 12.4 at the post while the truck is off. So just maybe it’s low and could use a little charge. I’ve driven it like 3 times since the new battery. Short trips and the truck seems to start normal for now….

like stated above the battery cable apparently goes bad quite frequently on these trucks as well so I may have to explore that route. I’ll have to check if my meter reads in Mv

 

[Fless]

I never got to a definitive conclusion, but the only thing I've changed is the door latch module. I didn't have any lights staying on, the RAP worked correctly, ECM connectors were clean and dry, etc. No problem since. I did tear the old module apart but the contacts didn't look all that bad. I figured since it was out I'd go ahead with a new OE one.

Make sure some odd light isn't staying on and that the RAP works correctly. Water in the ECM connectors can do weird things for a draw.

 

[Tonyv__]

I never got to a definitive conclusion, but the only thing I've changed is the door latch module. I didn't have any lights staying on, the RAP worked correctly, ECM connectors were clean and dry, etc. No problem since. I did tear the old module apart but the contacts didn't look all that bad. I figured since it was out I'd go ahead with a new OE one.

Make sure some odd light isn't staying on and that the RAP works correctly. Water in the ECM connectors can do weird things for a draw.

I’m gonna poke around a little bit after the baby goes to sleep. Hopefully get some answers.

 

[Yukondoit2]

Having this issue on my wifes 15 denali as well. Will be replacing the OEM battery cables as I had this issue with our previous Yukon (08 Denali 6.2 AWD) I replaced the cables and added some additional grounds from block to firewall and block to chassis. It did fix the electrical gremlins in the previous vehicle, so I'm hoping to have the same results with this one. Will check back in this week with my findings.

 

[Tonyv__]

Having this issue on my wifes 15 denali as well. Will be replacing the OEM battery cables as I had this issue with our previous Yukon (08 Denali 6.2 AWD) I replaced the cables and added some additional grounds from block to firewall and block to chassis. It did fix the electrical gremlins in the previous vehicle, so I'm hoping to have the same results with this one. Will check back in this week with my findings.

Any luck? I replaced battery and positive battery cable early august. The problem seemed to go away but just popped up again today