error code 40 indicates a line contactor OPEN fault during initial self test when powered on.
Possible causes: Line contactor, main wire harness, logic unit, right or left traction inverter.
-First thing i would do is check the inverter UVW cable connections on the inverters for heat related issues or corrosion or looseness. These inverters were notorious for burning out cable terminals at the inverter, in some cases melting the case around the terminal poles.

-Also check the line contactor itself, make sure the tips move freely and are not burned or melted, disconnect the battery and discharge the inverters (use a 150ohm, 25w resistor between the P and N terminals for about 5 secs. Then use a vom and check the voltage between the terminals to insure the voltage has been drained. If there are 2 drive inverters you will have to perform this proceedure on both inverters before doing maintenance on the system.)
Once you have discharged the inverters you can then check the line contactor coil to make sure it is not damaged, the coil should ohm out at about 44 to 65 ohms. the manual specs say [44ohms at -30deg C(-22F) to 65ohms at 80deg C (176F). Anything outside (below or above) of those parameters indicates the coil is faulty and needs replacement.

There are other things to check if none of the above is found to be the cause but we'll tackle that after you do the initial things i mentioned above.