Transmission Hesitation and Stalls
#14
08-24-2009, 09:22 PM
Re: Transmission Hesitation and Stalls
Took the hybrid to the dealer today...The transmission had acted up again. They did some things with the batteries and are sending some "Screen Shots over to GM for their take...I am also having the "Hybrid" Billboards taken off the side and front and the rearend of the rig. Hopefully the problem will be solved by tomorrow.
I will let you all know.
I will let you all know.
#15
08-24-2009, 09:39 PM
Re: Transmission Hesitation and Stalls
Well my story continues...now the brakes are acting funny. Normal braking and its like someone is squeezing them and the vehicle comes to a hault. A little disturbing...three days ago the front passenger door lock is not working, door stays locked even in park. What next? I got a call from GMAC from the last survey I took but I haven't had a chance to call them back. I am down to 17 miles per gallon from 25...not exactly what I signed up for, especially for the price of the vehicle. The stalling/hesitation is still happening, mostly when its really hot. I am sure it has something to do with the battery working over time. I am having no luck with the dealership, as they think I am crazy...I am seriously considering dropping off the vehicle and giving them the keys!
#18
08-25-2009, 09:32 AM
Re: Transmission Hesitation and Stalls
No, they are not able to diagnose. They told me last time to bring it in right away when the problem happens, but on the weekend or after hours, that is not an option. They keep telling me they have to experience the problem before they can diagnose, even though I have told them about this blog and other people who are having issues too. You had asked if my Yukon is 2w - actually its all of the above - has the option to do "all wheel" or 2w or 4w or manual. I keep it in 2w per the dealership recommendation for fuel efficiency.
#20
08-26-2009, 04:07 PM
Re: Transmission Hesitation and Stalls
Sarah,
It does sound like something is very wrong with your hybrid system. The braking is probably the lack of electric power. If you notice, the engine is usually off when you stop, unless it was sudden or the car was cold. When the engine is off and you are coming to a normal, gentle stop, the stopping is being done by the motor/generator. The actual ability for the Tahoe to roll forward (creep) by releasing pressure on the brakes is not how a normal car works. Normally, the engine is always trying to pull the car forward at idle, fighting the brakes. You modulate this balance with your brake pedal pressure. With the Tahoe, the vehicle wants to stand still when you let go of the brakes, only gravity will pull it (forward or backward) unless you are on level pavement, then you won't move at all. So, to allow for the same feel, the electric motor drives the car forward. Since it seems your electric motors or battery have mostly (or now maybe completely) failed, you will find braking to be a horrible thing unless you imagine you are braking a stick-shift car that is in neutral. Once you get your arms around that, it will feel normal during your drive to the dealer.
Now, about that dealer...
...obviously something is horribly wrong here. If the dealer will not attempt to find the issue, find another dealer (remember, GMC can be serviced at Chevy and Cadillac). My dealer tries pretty hard, but you can always sense that they hate spending time debugging difficult issues, as they don't get paid by GM for the troubleshooting time. But, being an electrical engineer, I can say with 100% confidence that any trained technician, worth a crap, will find the problem, or (at the very least) find the system that is not working right and get that info to GM engineering. I can assure you the GM engineers really, really want to know this stuff. They know that any new system in the field will have some issues and the sooner they learn the better the products will be.
Let us know how it goes.
P.S. I still stick to my squirrel-cage blower diagnosis. Do you hear the blower running with the car on, engine off and all the climate control off?
It does sound like something is very wrong with your hybrid system. The braking is probably the lack of electric power. If you notice, the engine is usually off when you stop, unless it was sudden or the car was cold. When the engine is off and you are coming to a normal, gentle stop, the stopping is being done by the motor/generator. The actual ability for the Tahoe to roll forward (creep) by releasing pressure on the brakes is not how a normal car works. Normally, the engine is always trying to pull the car forward at idle, fighting the brakes. You modulate this balance with your brake pedal pressure. With the Tahoe, the vehicle wants to stand still when you let go of the brakes, only gravity will pull it (forward or backward) unless you are on level pavement, then you won't move at all. So, to allow for the same feel, the electric motor drives the car forward. Since it seems your electric motors or battery have mostly (or now maybe completely) failed, you will find braking to be a horrible thing unless you imagine you are braking a stick-shift car that is in neutral. Once you get your arms around that, it will feel normal during your drive to the dealer.
Now, about that dealer...
...obviously something is horribly wrong here. If the dealer will not attempt to find the issue, find another dealer (remember, GMC can be serviced at Chevy and Cadillac). My dealer tries pretty hard, but you can always sense that they hate spending time debugging difficult issues, as they don't get paid by GM for the troubleshooting time. But, being an electrical engineer, I can say with 100% confidence that any trained technician, worth a crap, will find the problem, or (at the very least) find the system that is not working right and get that info to GM engineering. I can assure you the GM engineers really, really want to know this stuff. They know that any new system in the field will have some issues and the sooner they learn the better the products will be.
Let us know how it goes.
P.S. I still stick to my squirrel-cage blower diagnosis. Do you hear the blower running with the car on, engine off and all the climate control off?
