Had two problems today. The first one was when I drove to Kingston today and noticed that the transmission changed from O/D to 5th on a level piece of road when travelling at about 100 Kph. It upshifted into O/D after about 5 Km. The same thing happened on the return journey. The road in question was Hwy 33, from the Glenora Ferry, past Lennox Power Station. This is a level road on the Northern shore of Lake Ontario. I have travelled this road hundreds of times and never experienced this condition. Could it be temperature related since the air temperature was -12F outbound and -4F inbound?


The second incident occured when I went to start the engine in the parking lot of Walmarts in Kingston. Warning chimes and the ABS and Brake System warning lights came on and stayed on, along with 'Check Brake System' on DIC.
Switched off and turned key back to the 'ON' position... same symptoms.
Started engine and drove off.. brakes felt normal.
Stopped at McDonalds and no problem when restarting. (Must have liked the smell of the french fries)
Stopped at another place and on restarting, the same problem occured again, which lasted until I turned the engine off on arrival at the Glenora ferry. On restarting, to drive off the ferry, there was no problem.


Any clues as to what caused this?

i had the same problems with the brakes... same symptoms... took it to the local dealer and they cleared the codes said there wasnt a problem......





if u get a solution to the brake problem .... please let me know

Just got truck back from the dealer. The cause of the lights coming on was as follows.


'Scan test codes


U1024 - Loss of communication with Trans


U1026 - Loss of communication with ATC & C0201 - ABS enable relay'


Clean codes & Road test - Light did not come back on.





The Service Advisor told me that 'It must have been caused by the cold weather'. I am dubious of this, I cannot see GM designing something that will not work in these low temperatures (-8F today)

Just had the same problem with the brakes again. Temperature is 3F. Am taking it in tomorrow for another scan. Will report to the forum on what the dealer says.


Eric, do you have any clues?

Just returned from the dealer. They cleaned the connector pins going to the ABS Enable relay, then cleared the codes. Lets hope this cures the problem.


If anyone else has had this problem, I would be interested to hear about it and their solution.