A local transmission shop told me today that maybe my new altenator has the wrong size pulley, that is why my transmission is shifting funny, does this sound possible? He said that the rpm reading might be out now.

 

Difference in pully size would mean different alternator speed at a constant rpm. This is not a constant speed engine therefore pully size theory (to me) is bunk. If your tranny is shifting in and out of o/d, I would clean the contact where the wire comes out of the alternator. This could be a source of electrical noise affecting your electronic tranny..

 

I believe the alternator pulley theory is true for the older non electronics diesels.

MikeyB

 

After installing new altenator, i have to let off the fuel for a split second before it will shift into 2nd....shifting to 3rd and OD are working perfect. Even when I stop and start in traffic, i have to let off the fuel to shift into 2nd. It will stay in OD all day no problem when on highway.

 

I was having the shifting problem too, check alt. connections and clean battery terminals, then clean them again. I don't know why but any little bit of corrosion on the battery terminals and the trans. starts doing funny stuff