Yukon Hybrid No start after not being used for 2 months
 

Hi all

I have a 2009 Yukon Hybrid with 55k miles which is currently having a no start situation after I left it in the garage for 2 months. It started once 2 days ago and hasn't started since. Hybrid and BECM are currently putting out a P0B3D Hybrid battery 1 circuit low voltage. I have uploaded photos below of the error codes and the live data from the hybrid module. What can I do to solve this no start situation?


https://cimg4.ibsrv.net/gimg/www.gre...65194a1455.jpg
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Re: Yukon Hybrid No start after not being used for 2 months
 

you need to charge the hybrid battery. easiest way to do this is using that scanner. it looks high level enough to have a special fictions section. look for jump assist.

also you can search here or just Google it. the tsb for jimp assist has been attached to a few threads or it pops up with a Google search pretty each too.

but basically your scanner tells the inverter to charger the hybrid battery off the 12v battery with a 20amp charger connected to it.


just as a heads up, these trucks have quick disconnect battery terminals while the non hybrids do not. just for the storage discharge. your owners manual will tell you how to store the truck based on the time it's going to be down.

Re: Yukon Hybrid No start after not being used for 2 months
 

Thank you for your reply. I have tried to use jump assist mode before and I will just re activate it again to charge the hybrid battery. I'm just gonna have to find a 20 amp charger as I only have a ctek 5 amp.

Re: Yukon Hybrid No start after not being used for 2 months
 

I haven't read this in a while. might double check if a 5amp will work or not

Re: Yukon Hybrid No start after not being used for 2 months
 

Indicates the jump will abort if 12V drops below 11.1V, so I presume the 20A charger spec it to prevent that. Recommend fully charging the battery before making an attempt.

Another option would be to simply jump the 12V via jumper cables and another running car. Should provide well more than 20A and stay well above 11.1V... likely not drop below 13V.

Re: Yukon Hybrid No start after not being used for 2 months
 

The 300v high voltage battery is below starting voltage. I just joined this forum to tell the community how I solved this. There is a function called jump start assist. I used a creader elite "knock off" tech 2, off amazon for $150, to engage this function. There was an additional $34 temporary upgrade for the high voltage hybrid battery function. But with that I found the jump assist function and I'm charging the dead high voltage system using the 12v battery as I'm typing this. There is a pdf floating around the web on the procedure. Active Enthusiast posted the file. The jump assist function is found under auxiliary power module (APM).

Re: Yukon Hybrid No start after not being used for 2 months
 

do you have the users manual ?

Re: Yukon Hybrid No start after not being used for 2 months
 

Just to update this thread. I have tried to use jump assist to no avail because it keeps on aborting everytime the hybrid systems pulls up a MIL light. Is replacing the hybrid battery the next step to this? The battery that is in the car is still the original one from 2009

Re: Yukon Hybrid No start after not being used for 2 months
 

I've never used jump assist, only read about it. do you know what code the mil light is being set for?

you can use the scanner to see the cell voltage in the hybrid pack. but honestly, being oem from 09 it's probably weak. these trucks are hard on the packs. not sure that's why it won't jump charge, but if you plan to keep it a while, it's probably not a waste of money to refresh the pack anyways.

Re: Yukon Hybrid No start after not being used for 2 months
 

https://cimg9.ibsrv.net/gimg/www.gre...733f4acf6c.jpg

Hello attached are the trouble codes. Jump assist is then the scanner instructs the car to charge the hybrid battery through a jump pack connected to the 12v vattery. Any help is appreciated. The car still hasn't started until now.