Hello all, hope someone is able to give some advice with this issue I am having with a forklift that was I recently purchased. This is my first forklift and the issue was known when bought. The check engine light and seat light is on but will still move forward and reverse as well as raise the mast and side shift in both directions. The mast will not lower and when attempting to shift forward, RPMs will raise and struggle then engine will die if lever is held too long

I have checked all fuses, replaced alternator/belt and searched all over the internet for the manual and have not succeeded. I would like to check the codes without a scanner if possible and fix this potentially small issue. I would like to avoid having a technician come out and fix a small problem that I could have repaired easily if thats the case.

Please let me know if there is any other information you need from me to better diagnose.