edward is right
you can use the drs switch and set everything back to defaults but you will still need the manual because sometimes the defaults are not completely correct and it may leave you stranded with a code for an incorrect setting. I've seen this before and trust me, you WILL need the settings for that truck in front of you when you go through the setup routine.

Great info ,Thank you. First thing on schedule Monday is to change the battery connectors to suit customer's application. I have a feeling a discharged battery may be issue,from what you said. Thanks again.

I think you will need the manual in front of you, but the short of it is that you can use the DRS switch to reset everything to 'default,. and to properly set up all the options.
1 caveat, make sure the battery is good and well charged before you get there. this unit has a lower speed setup that happens when the available battery amps goes too low, while voltage is still OK, preventing a too small battery from being used when working, but allowing a smaller battery pack to be used moving the truck before delivery and matching with its permanent battery.

Thanks for the reply. It is an old (used) truck. Was sent to my customer from one of their other plants. My understanding is,they had set it up this way for a special application at the other plant. I have resources to get the service manual next week. I am trying to get a head start before the week starts.

is this a new truck or did it just start acting this way?
sounds like a "demo mode". I would say to get the dealer in and let them setup the truck properly, they may have to do a pre delivery inspection, and setup so that your truck is covered under the warranty.