If the vehicle was driving with no issue and all of a sudden lost forward gears, it is most likely a shift solenoid issue. Basically it is not engaging 1st gear but it can engage reverse.
I am not familiar with the Acclaim shifter but you should have a manual shift option. This means you have P,R,N,D,L 3,2,1? If when you put it in D and it doesn't move, try putting it in L or one of the numbers. If it engages in these position then most likely it is a solenoid issue.
Let me know if this works and we can go from there. Thanks
May 8, 2020 at 1:20 PM