I have a 1990 3.0 4x4 auto. It will not stay in o/d if I hit a bump in the road. Hit another bump and it might upshift. Then it will try to shift into o/d but it kicks down half a second later and will do it repeatedly until press the o/d off switch. Being that road bumps affect this could it be a wiring issue? Anyone have any ideas? Something loose in the tranny? Thanks.

 

So I'm following the diagnostic chart from the online manual, which one is the solenoid wire connector? I need to unplug it to do the manual shift test.

 

How long have you had it? What speeds is it occurring at? Sounds normal for a 3.0 auto

 

Just did a code check, flashing code 42 and 62. VSS No. 1 and No. 1 solenoid. Do these have anything to do with o/d?