Hi, I am having problems with the automatic transmission in our 3500. While in park the trans temp sensor light and chime goes off and on along with OD light. Put in gear and drives ok until overdrive kicks in, then light for temp and OD comes on again. I don't know if it is a certain amount of time or temp but once the tranny temp gets up to 120 everything works good. The only thing is after the temp light on OD starts working I loose first gear at takeoff. I've done the home remedy things such as checking all grounds, wrapping the alternator wire, running a direct ground wire from battery to firewall and installing the BDS noise isolator. Not fixed yet. Don't know if there is anything else I can do before going to a transmission shop.