4l60e does not shift

[Mister1500]

Hello, I am new and have been looking for a good source for info. Long story short my son fighting cancer just had his veh totaled by a deer, I loaned him my car so he can continue his treatments. I have pulled out my 1995 Silverado with 270,000 miles on it. It is not shifting. I have power to the connector at the trans, I have replaced the ignition switch, checked fuses and grounds I can find, I have replaced the PCM and the harness in the pan. I still have codes 66, 67, 81, and 83. Every once in a while if shifts perfect. Most times I have to start in 2nd and shift to 3rd. Any help is greatly appreciated. I am looking for thoughts. Thanks in advance! Newbie.

 

[Frank Enstein]

Try cleaning the connector that plugs into the trans. if it's dirty it won't shift.

The symptoms point to a broken wire or a bad ground.

Others have more experience with the 4L60E than I do.

 

[Mister1500]

Any suggestions on how to clean the harness connector? Does it come apart to check all the pins?

I appreciate the suggestion

 

[Frank Enstein]

No need to pull the pins. just unplug from the trans and spray it out with contact cleaner. make sure the contact cleaner won't harm the plastic.
My 4L80E did this to me and I only had starting fluid with me to spray it with. It got me home.

The grounds are the most likely cause.

 

[gldixon86]

So I just had my 99 gmc suburban 4l60e rebuilt an after it gets warmed up it’s still shifting super hard into 1st would that be my torque converter???

 

[stutaeng]

So I just had my 99 gmc suburban 4l60e rebuilt an after it gets warmed up it’s still shifting super hard into 1st would that be my torque converter???

Probably not. I would start a new thread since it doesn't seem like it's not related to OP's problem....

 

[Mister1500]

No need to pull the pins. just unplug from the trans and spray it out with contact cleaner. make sure the contact cleaner won't harm the plastic.
My 4L80E did this to me and I only had starting fluid with me to spray it with. It got me home.

The grounds are the most likely cause.

I have tried to find and locate all the grounds but even the GM dealer I went to anymore can only give me an alldata print out. Does anybody know where all the grounds are so I can check them?

 

[1997]

you're in the right place, thank Hatzie for the factory service manuals....

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

read thru and find your code (s), it lists the causes and gnds.
i found it easiest to get the pin out for the ECU and test connections from there, pull the connector (s) from the ecu.

 

[Mister1500]

you're in the right place, thank Hatzie for the factory service manuals....

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

read thru and find your code (s), it lists the causes and gnds.
i found it easiest to get the pin out for the ECU and test connections from there, pull the connector (s) from the ecu.

I hate to ask, but I’ve only got a smart phone to work off of and can’t see well. Can someone “clip” the image of the connector and pins so I can try and ohm them out?

 

[Mister1500]

Can anyone point me to all the grounds on this? 5.7 4l60e Silverado ext cab