Hey everyone. Im new to this forum and still somewhat green when it comes to working on compact machinery. I have a Bobcat S740 thats throwing the M7504 "Drive No Communication" code. There's no diagram sticker on the fuse box and I dont have a Service Manual, Operators Manual for this so I have no idea which fuse/relay the controllers are on so I can start figuring out whats wrong. Only thing Ive done so far is replace and rechecked all fuses and relays. Would anyone be able to help me with a fuse box diagram, wiring schematic or some kind of diagnostic procedure? I really appreciate any and all help!
Hello. Look at the connector on controller under the seat, but there is a high probability that it is the controller that has failed. This model may have two different controllers (#19 or #30), write the serial number of your forklift.
Hey Elit, thanks for the response. Ok awesome, thank you so much for the picture and about that harness behind the seat! I'll check that first thing in the morning. The serial number to my unit is B3BT11419
Hello. Did checking the wires and connections help? P.S. According to the catalog, the number of your controller is 6679485
Sorry its been a while everyone, I just got back off vacation. I did check all the wires behind the seat: checked for voltage, ground and continuity and Im getting the same results at both controller connectors. Everything on the right controller works as it should but the only thing working on the left is the horn button
Are you referring to the joysticks as controllers? Which is not really incorrect because they are Canbus. However the drive controller the code points to is a computer box underneath the cab, that the joysticks connect to. The code is coming from the mainframe or Bobcat controller, saying it can't communicate with the drive controller. That machine has about 7 controllers on it. . .
Thank you for the reply ozarkag. Im sorry, yes I do mean the joysticks when I say "controller". I didnt even think about that verbiage conflicting when talking about an actual controller. What Im not understanding is that at the RH joystick connector, where it plugs right into the bottom of the joystick, Im getting 2.5V on the purple wire and the purple/white wire, getting ground on the black wire and 12V on the orange/white wire and that RH joystick works as it should. Im getting the same exact readings from the LH joystick connector and the LH is not working. I have zero access to and cant find ANY type of wiring diagram, wiring schematic, diagnostic chart or anything online. So I dont know if those readings that Im getting are right or not. While I was on vacation last week, the customer went ahead and ordered a new LH drive joystick. My coworkers plugged the new joystick in and the same thing is still happening. I would be grateful to any thoughts/help or leads on some wiring literature if anyone has some haha.
Try switching to H pattern, i suspect both joysticks will not drive, but will lift and tilt the loader. The code points to a communication problem between the drive controller and the mainframe controller. Unless you obtain the serial number correct workshop manual/ wiring diagram and check power, ground and omm wires there is not a lot of testing to be done. Physical wire harness checks would be a good start. But will probably require a bobcat tech with computer to diagnose, and for certian if it is a failed controller.
Attached are several screenshots from bobcat parts. One shows the Gateway and other controllers and harness. Other one shows drive and SJC (joystick) controller. Sorry, no screenshots. Photo posting is glitch for me
Did you ever figure out what was causing code, i have a S750 throwing the same code. I had another machine with the same p/n drive controller that i swapped it with and it did not fix code. all the powers and grounds are good to the controller.