08-28-06, 11:44 AM
Is anyone else experiencing hard downshifts between second and first gears? I had my 04 SRX in for service to fix a vibration, the shifting and the creaking roof (again). They replaced bad motor mounts (V6) and the trans mount which took care of the vibration but the trans still downshifts hard.
08-28-06, 02:41 PM
Yes..had very violent "intermittent unwanted downshifts", as GM bulletin described it. It occurred in my '05 V6 RWD when coasting at slow speeds, usually under 20 mph while approaching red lights etc. Following is the GM recommendation/instruction which my dealer gave me. Unfortunately he cut off the top portion of the bulletin, so I have no bulletin nbr to give you.
"The cause is a weak internal vacuum brake booster return spring resulting in the brake pedal position sensor not returning to the off position. This unwanted brake pedal signal (depressed) is sent to the EBCM then communicated from the EBCM to the PCM via class 2. The PCM thencommunicates this message to the TCM resulting in a downshift command during this type of driving maneuver. Replace the vacuum brake booster to repair this concern."
The part number is 88967237. That was 10000 miles ago, and no problem since.
Hope this works for you.
08-28-06, 10:37 PM
Thanks for the info, I'm taking the car back to the dealer tomorrow for a host of problems including this one.
09-05-06, 08:30 AM
I was wondering if you could get me the name of the dealer so that I can get a copy of the TSB. My dealer is giving me the "we can't duplicate the problem" run around. I took the vehicle on a camping trip this weekend with a rack in the hitch with camping gear and it really shuttered on acceleration while loaded. I may have to load the vehicle again and take it to the dealer.
09-05-06, 05:14 PM
My downshifting problem was on DECELLERATION, not acceleration. The engine is smooth and strong on acceleration. The problem was fixed by DEW CADILLAC of St. Petersburg, FL. Phone:727-822-2019 Fax:727-896-0125
Good luck. Hope you get it fixed.
09-06-06, 09:26 AM
Thanks for the number. When the engine was shuttering on excelleration the check engine light came on. It cleared itself at the dealer and the shuttering stopped. Speculation is a misfire code probably due to some bad gas.