97' Blazer 4x4 LT. 147K MILES. Auto transmission.Just recently the trans is acting funny. When I take off from a stop, the rpm's go real high then it shift's hard into 2nd........ and won't shift any more.I do have the "engine service light on" which I know I have to pull the code, but I just wanted to get some possible ideas now. I have had the code PO740 CODE come up in the past , but it seem to go away. Thanks for the help and I'll be sure to post back with the code soon.
Got the codes today. PO440 & PO306. No codes on the trans. showed up.This thing is flip'n out!!When itshifts, it almost takes my head off it shifts so hard.Got to start out in #2 gear position from a stop, then shift into "D"so itwon't rev so high. I really don't want to take it in to get stroked. Anything I can check myself? Thanks.
Here's some more info on this............looks like I need to manually shift from a stop,starting in 2, then 3 then "D". Even around corners I need to down shift to 2, then 3 then "D" I thought it may be a fluid problem but fluid is fine. I'm lost. Also.....the speedometer is fluctuating......it won'tmove until I get up to about 30 mph, then it moves up from zero to the speed.

 

Got the codes today. PO440 & PO306. No codes on the trans. showed up.This thing is flip'n out!!When itshifts, it almost takes my head off it shifts so hard.Got to start out in #2 gear position from a stop, then shift into "D"so itwon't rev so high. I really don't want to take it in to get stroked. Anything I can check myself? Thanks.

 

Here's some more info on this............looks like I need to manually shift from a stop,starting in 2, then 3 then "D". Even around corners I need to down shift to 2, then 3 then "D" I thought it may be a fluid problem but fluid is fine. I'm lost. Also.....the speedometer is fluctuating......it won'tmove until I get up to about 30 mph, then it moves up from zero to the speed.

 

No one has any ideas on this??? [&:]

 

I know that with the holidays and being off work from our yearly scheduled shut down, I have been very busy with other things outside. I imagine that is quite common with many of our other members as well.

About your problem, what have you done to try and remedy the situation? What are you capable of doing? Automatic transmissions are not for the typical DIYer to attempt to repair.

The fluctuating speedometer sounds like a failing speed sensor at the back of the transmission. This sensor a long with a host of other sensors is used to determine proper gear selection.

Now lets look at your current and past codes that you have listed:
P0740 - Torque Converter Clutch Circuit
P0440 - Evaporative Emission Control System
P0306 - Cylinder #6 Misfire Detected

When you verified the fluid level was proper, you did so with the vehicle on a flat, level surface with the transmission fully warmed up, in park, with the engine running, correct? What did the transmission fluid look like? Does it do this more so when the transmission is cold, warm, or pretty much all of the time?

 

Thanks for responding........yes I checked the fluid level as you described. It looked ok........as good as it would on a dip stick. Didn't smell burnt. And here is the latest on this since I postedon the 25th. I took it on the freeway for about 15min and soon after that everything is BACK TO NORMAL. Speed-o is fine, trans is shifting fine and normal operation isBACK!!!! THIS ONE IS A MYSTERY TO ME!! Any ideas? Thanks!

 

Damaged wiring harness to the transmission? Corrosion in the connection? I am not sure..

 

I know it's crazy.........will a good scan at the dealer tell me what happened in the past when there were problems?

 

It is possible, but intermittent problems may not result in a stored code... You could try. It really depends on whether the last time someone accessed the PCM with the appropriate scan tool cleared the history data.

 

Thanks............Happy Holidays