another auto trans acting up. what might it be

[j.barrett]

hi everyone thanks for taking some time to read this.. 

I was driving home today on the freeway thinking how nice my truck was running. I got into town left the shop light and the truck stayed in first gear. I let off the throttle and it shifted into second. It held second gear until I let off again. 

I have a converter lockup switch and the shift relay pulled and jumped. It's been this way for years. Now this happened...

 

Another note I have 2 old optima batteries that are having a hard time starting the truck when it's cold in the morning.  

I'm open to hear  theories ideas ect. 

 

Thanks again

[CSM]

Any reason the linkage could have been jostled loose?  Ido look over the linkage and scan for codes.  

Mine will do that on certain smarty torque management settings.

[Mopar1973Man]

Weak batteries will cause problems on the PCM possibly an alternator noise issue.

As for the linkage just check quick to be sure the throttle bellcrank and the transmission key down arm are moving at the same time. You should barely be able to see the transmission arm while moving the throttle bellcrank. They should move together at the exact same time.

[IBMobile]

My rule of thumb is 'fix what you know is wrong first'.  You know you have old weak batteries so replace them be for they die on you completely, then test the alternator for DC/AC out put and the linkage for proper adjustmet