FIRST BLOCK THE TRUCK SO THE DRIVE WHEELS ARE OFF THE GROUND!

code 04 description
Start switch input low after initial start up.

Symptom
fwd or rev contactor will not pick-up

Possible cause
fwd or rev directional switch closed on initial start up
Depress accel and see if code 03 or 02 comes up after start up if 03 then the rev switch is closed if 02 comes up the fwd switch is closed.
Possible cause 2
Excessive leakage from TB2 to battery negative
Check voltage at TB2 with key and seat switches closed and directional lever in neutral. voltage should be greater than 60% of battery voltage.

If less than 60% voltage. remove wire from TB2 and measure ohms from wire to terminal N on traction panel. Value should be greater than 22k ohms.

you may have a glitchy switch. this is normally an out of sequence code on start up.