'09 Yukon, 120,600 miles

This...my vehicle is doing everything described below.

http://www.autoserviceprofessional.c...brid-bump-jerk
Customers may comment on either of two drivability concerns. Bumps, jerks and/or surges caused by the auxiliary pump which occur during a transition into, out of, or during an Auto Stop, as observed on the tachometer.

A lull (clutch slipping) followed by a kick (clutch grabbing) during acceleration while in Auto Stop or during a transition to Engine On. This condition typically occurs just before and engine restart is observed on the tachometer.Surge or lunge during deceleration below 25 mph with light to moderate braking. This typically occurs after the tachometer drops below idle speed to anter an Auto Stop. These concerns may be caused by an auxiliary transmission fluid pump concern or a slipping clutch within the transmission.

2 trips to GMC dealership with no diagnosis as reported issues cannot be duplicated, no codes. The 2nd trip they cleaned the throttle body which did nothing to resolve my issue. 3rd trip I provided the tech bulletin above. Issues could not be duplicated, no codes & the aux trans pump control module date code could not be found. Apparently it is located on a paper sticker that due to exposure to the elements is no longer on my module. Short of just throwing $$ at the problem and randomly replacing parts I don't know what to do. Any suggestions are appreciated!! I love this vehicle and was looking forward to driving it 200K+ but I cannot keep driving it like this.

 

See my reply to you in my other thread. Sorry to say most dealers are not so good at finding issues if there is not someone to show them the way. Not everything is in a book or on a list.

 

 

I have corrected this problem a few times on my 09 by unplugging the connector that goes to the aux trans pump and replugging it in. I believe it resets the pump control module, similar to disconnecting the battery. I later found my 12 volt under hood batteries cable loose. Retightened and unplugged-replugged the connector for the aux pump module and havent had an issue since. Been 65,000 miles. The connector is under the battery and above the steering box, 4 larger wires, blue, red, yellow and grey.

 

I know this is an older thread, but your vehicle needs a new hybrid battery. That is the exact same symptoms I had with my vehicle. I replaced the Hybrid Battery, immediately fixed it.

 

you can always bypass AutoStop by using M4 to disable auto surge feature


still get the good mpg

 

Hybrid battery is probably weak. I had the same symptoms before replacing mine. Could be pretty concerning if in a spot where you were trying to pull out into traffic and the silly thing hesitated for a couple of seconds. Now I can spin the rear tires anytime I want from takeoff LOL 385 hp will make these old beasts move pretty good.

 

You can spin tires in Hybrid mode or Manual?

 

I tested my Hybrid batteries. All are pulling 8.2 volts. What codes did you get?

 

Resting voltages for the battery modules do not tell how good the battery is. Only when they have not been charged for a long time (to allow time for self-discharge) can you start to see which modules may be suspect. The only true way to know if the battery is good is to read the voltages under load. Buy a bluetooth OBD2 reader and log the 20 block (pair of modules) voltages. You will find that blocks 1 and 20 tend to have a higher voltage than all the other blocks when being discharged because they are the blocks that have the least damage from heat (they are at each end of the pack). Read the State of Charge % and the lower the SOC%, the more the voltages will vary from each other.