Crown RC3020-35:
RC3020 Troubleshooting : No FWD/REV

Having trouble with my residential workshop RC3020. I have spent 12 hours toning out wiring throughout the lift with every access panel and plate removed.

My FWD/REV performance has gone from intermittent to absent. Batteries at 38.6V; Amperage good; fluids good -- before your ask ;-) I was able to get "some" movement if I unplugged the batteries and inserted. Sometimes it operates, sometimes a single side of the FWD/REV solenoid clicks. If this happens then I need to unplug/plug to get flow.

At this point, I have performed the following diagnostic steps:
+ verified main power solenoid function
+ verified that all connection solenoids operate correctly with 24V
+ chased all signal wires/leads from solenoid to ECU
+ ohm'd the micro switches on the control stick

The lift and tilt are still working fine. The steering drive is operational.

What am I missing? At current, the only solenoids operating are the main power solenoid and the hydrolic pump solenoid. I'm not hearing or seeing the other solenoid/switches operating. I "think" I'm only getting 18V to these solenoid/switches.

Other tips from people far smarter than I?

Thanks!

/jm
  • Posted 4 Jan 2012 08:43
  • Discussion started by joelmcf
  • Texas, United States
Showing items 16 - 18 of 18 results.
check the connections at the z connector at the logics. also check the inputs the the terminal board on the card. You need a good pot sweep and the other inputs need to be satified as well. don't forget about those stupid steering switches everyone gets burnt by those.
  • Posted 15 Feb 2012 04:36
  • Reply by mfctech
  • Ohio, United States
Truck has a set of contactors for each drive motor. For them both to be powered, the steered tire must be within 30 degrees of straight. I would check or replace the floorplate or deadman switch first. I have seen some resistance in this switch allow the power steering to come on, but not the travel. The next switch to check is the one under the brake pedal. The third and fourth switches would be the forward and reverse switches. These operate off a cam when you move the control handle. I would also check the two 140 amp fuses on the contactor panel. One is for the left drive motor, and one is for the right. If you have the steered wheel turned to the left of right, and one drive fuse is open, you might not get the contactors to pull in. The motor controller will sense an open circuit and not allow travel. I would also check to see if you have any contactors welded or stuck. The 1A, or high speed contactor being welded will prevent travel. Pull all the plugs from the EV100 control card and make sure all the female pins are fully inserted. They must be in order to contact the male pins in the control card and allow travel. There are two switches on the steer wheel assembly that open as you turn left or right that you can check. The last resort is to call a lift truck repair company. Most will have a handset you can plug into this to do some diagnostics. If they send someone out, make sure to tell them they need to bring a EV100 LX hand set. Many brands of lift trucks used this GE motor contoller such as Clark, Mitsubishi, Komatsu, Hyster, Yale, Caterpillar.
  • Posted 9 Feb 2012 14:17
  • Reply by Liftdoctor
  • Indiana, United States
check pot and forward reverse switches does this unit have a lx card can you get your hands on hand set
  • Posted 8 Feb 2012 13:16
  • Reply by brummie
  • British Columbia, Canada
happy forker

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CEO, Caterpillar Inc
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Chairman of the Board of Directors, UgoWork
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