View Full Version : Strange shift when cold
APDMC6008
12-05-2005, 03:34 AM
Hello all....
Lately I've been noticing that the truck shifts differently when it's cold out. It tends to hang onto a gear and then decide to shift...a delayed shift. When it does shift, it's not as smooth as it is when it's warm. I do remember my Silverado had a statement in the manual that stated it would shift differently when cold in order to help the engine get up to operating temperature. Do the TB's do that as well? The fluids and everything are topped of and other than that look fine. When the truck is warm there are no problems.
ScarabEpic22
12-05-2005, 04:05 AM
Hello all....
Lately I've been noticing that the truck shifts differently when it's cold out. It tends to hang onto a gear and then decide to shift...a delayed shift. When it does shift, it's not as smooth as it is when it's warm. I do remember my Silverado had a statement in the manual that stated it would shift differently when cold in order to help the engine get up to operating temperature. Do the TB's do that as well? The fluids and everything are topped of and other than that look fine. When the truck is warm there are no problems.
Short answer, yes, it is designed to do that. On my 02, when it is cold, it takes even longer than the regular .5-1sec P to D shift, and it shifts from 1-2 later than when it is warm. I just drive it easier up the hill by my house, and then once I get on the 35mph street, it is running at about 150-180 degrees, so I tend to get heavy on the gas again.
tblazed
12-05-2005, 10:55 AM
There was a TSB ( 03-06-04-018) released about that back in March 2003 for the delayed and harsh upshift when cold. It requires reflashing the PCM. I had it done then and the upshift problem went away.
Additional info... the TSB was revised to 03-06-04-018A in Dec 2003 for updated warranty info.
When I had this done, my cold hesitation and long delayed 1-2 upshift was cured, also it made the off idle throttle more responsive with all driving conditions.
Cold Idle Fluctuation at Altitude, Hesitation on Acceleration or 1-2 Upshift Delay (Reprogram PCM) #03-06-04-018A - (12/08/2003)
2002 Chevrolet Trailblazer
2002 GMC Envoy
2002 Oldsmobile Bravada
with 4.2L Engine (VIN S - RPO LL8)
Some customers may comment on one of the following conditions:
- Idle fluctuation for a few seconds on the first start up after an overnight soak at higher altitudes.
- Hesitation on acceleration, this typically occurs with engine coolant temperatures between 60-80°C (140-175 °F).
- 1-2 upshift delay at throttle openings of 25% or less and ECT between 7-30°C (45-85°F).
Cause
The existing PCM calibration may not be optimized for all conditions.
Correction
Reprogram the PCM with the latest service calibration available from Techline.
itchyfishnv
12-05-2005, 07:33 PM
i had this problem i actually replaced my battery and everything was fine.
APDMC6008
12-05-2005, 08:12 PM
My battery AND cable are brand new. I don't see how a battery would affect transmission shift points...lol. How did you get to that conclusion to replace the battery and see if that would work? :confused: