I read your post l do not have a wiring diagram of this truck but can help you fix this problem First please remove the wire that you put on to bypass the netural switch someone will be hurt or killed when they are ran over by the lift truck. next put back the factory wire to the starter s post get a volt meter and take postive lead and install it on s post next take negative lead and install to negative of battery crank truck if volt meter is dropping to less than 10volts you are loosing it in harness you need to check for voltage drops in starter circuit l know a way to repair to get to crank correctly without bypassing harness first you need to get a new 30 amp starter relay mount it near the starter it should be 5 post relay 2 post will be coil some relays are marked 85 and 86 take the wire that Is on the starter s post and install that on post 86 or 85 on relay does not matter. Next make a wire up at least 10 gauge and install that on the other coil side of the relay 85 attach the other end to a good ground next make a wire up this time make it 12 gauge attach that to battery on relay will be marked with 30 on relay then attach the other end to positive of starter cable next there are two post left on relay one will be marked normally open and normally closed make another wire 10 gauge and attach that to the normally open post on relay attach the other end to the s post of the starter on relay will be marked 78 leave the other post blank of you hook up wrong will keep cranking what you are doing is controlling the coil side of the relay with the key and battery direct to starter. netual should not be bypassed hope this helps