I have a 2005 chevy express 3500 4.8L automatic. It shift hard every time I get on a highway and come back to street traffic. I replace all 4 solenoids on the transmission and the problem still. can someone help me find out what is happening. thanks

The 2005 Chevy Avalanche is available with different transmission and shift options, which can affect the number of transmission shift solenoids present.

However, generally, the 4-speed automatic transmission (4L60E) used in the 2005 Chevy Avalanche typically has a total of 7 transmission shift solenoids. These solenoids are used to control the activation and deactivation of the transmission's clutches and valves, allowing the vehicle to shift gears smoothly and seamlessly.

It's important to note that the number of transmission shift solenoids may vary depending on the year, model, and configuration of the Chevy Avalanche.
>

Need to know engine size ..,mileage..,Automatic or shift ...?.Is it full time 4 wheel drive..?

sounds like you may havea torque converter lockup issue, one way to check is while in slower traffic (15-35mph) gear down your transmission such that you are at a higher rpm (2000-2500) then take your foot all the way off the throttle, if it is in lockup your engine rpm will stay about the same, if not it will go to about idle.

If the tcc doesn't unlock while shifting it will shift very hard and if it slips it will make your temperature increase

Drive the vehicle in "D". The D selection is the overdrive. You can consider the overdrive as a fourth gear. The D3 is simply third gear, and if driven in D3, the transmission will never shift into overdrive when needed.

When the blower is on speed 5, it is a direct 12 volts for high speed and the first four operate through the resistor, check your breaker for the blower motor to insure it is not cutting out.

try LUBE GAURD at NAPA it is a additive that is synthitic,sticking valves sounds like the colpret

This is a major problem and I too have reported the issue to the National Highway Traffic Safety Administration. Please take the time and do the same. They can be contacted online at safercar.gov or BY PHONE: Call the Hotline, Monday-Friday 8am to 8pm at (888) 327-4236 , TTY:(800) 424-9153.
Sep 04, 2009 If you read and google you will find over 200 more complaints. This is an issue only GM/Chevy can fix. Report it to www.safercar.gov and the Department of Consumer Affairs. I have been battling this issue for 2 months.

A reason for hard shifting could be a problem with many things with various degrees of seriousness. It could be your ATF( automatic transmission fluid) is low or broken down and old. This would cause the hardness and the reason for stop and go traffic effecting it. Another possibility is your transmission is just shot, and the timing gears inside are worn and not properly shifting at the correct RPM causing a **** during shifting.

Some possibilties, not all!

~Lucas

The Dodge vehicles have an external solenoid pack that runs the trany.My experiance the solenoid pack starts to leak trany fluid into the electrical conector.Sometimes you can clean the fluid out with a spray cleaner and compressed air and it will temporaly fix the problem.If it does you know the solenoid pack will need to be replaced.

I had the same thing! It was a computer issue. It only cost me about $35.00.