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FIX IT MAN, Master Technician
Category: GMC
Satisfied Customers: 17368
Experience:  Master Automotive Technician
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I have 2008 Yukon xlt 1500 with 170k miles. When I am

Customer Question

I have 2008 Yukon xlt 1500 with 170k miles. When I am slowing down to a stop the car has a rumbling sound and vibrating sound as it shifing down. I nitice the same sound when the engine shits form 8 cyl to 4 cyl, if I step on the gas it will go away when it switchs back to 8 cyl, Also my check brakes and traction assit lights are on along with the warning ding when pitting into drive
Submitted: 1 year ago.
Category: GMC
Expert:  FIX IT MAN replied 1 year ago.

Hello, my name is Bobby. Thank yiou for the question. Can you tell me if all of these issues appeared to start at the same time or at different times?

Customer: replied 1 year ago.
Different times.
Expert:  FIX IT MAN replied 1 year ago.

Thank you. Can you tell me if it seems as if the idle is getting really low at that time also?

Customer: replied 1 year ago.
No. That's ok. A little rough @ times but ok. I did change the plugs a wires.
Expert:  FIX IT MAN replied 1 year ago.

Thank you. These problems may or may not be related. I would first check charging voltage. If the voltage in the system drops low enough then both of these problems will occur. This vehicle has a history of battery cable issues that will cause voltage problems. If all of this is fine then the noise or vibration may be from the cylinder shit down system. If the solenoid pack is failing or if you have a cheap oil filter on the vehicle then this will occur. The brake and traction control issue may be the result of a failing steering sensor or yaw sensor. Both of these are common also on this vehicle. Did you plan on fixing this yourself?

Customer: replied 1 year ago.
I will check the volTage today. Should I just replace the sensors.
Expert:  FIX IT MAN replied 1 year ago.

I wouldn't. The best thing to do would be to install a scan tool that reads these modules and see what they say when the lights come on.