All the latest Skyjack boomlift models utilize a function control module called the OCM – On-board Control Module, or the newer version; the SCM – Skyjack Control Module which are located in the platform control console. The OCM/SCM has a two line LCD display and a membrane keypad that allows the technician to access the programming without the need for a separate plug-in calibrator. Once the programming is accessed, the technician can monitor function status and make adjustments to function speeds similar to adjusting the trim potentiometers on a joystick circuit card.
When troubleshooting a ‘no functions at platform controls’ problem, there are a few tests that need to be done initially to help determine the problem. With the machine powered up, the key switch in platform position, and both the base and platform emergency stop buttons pulled out, please check the following items.
Using a voltmeter, check wire 04 for 12 volts at the start or horn switch. Wire 4 (or 4A if generator equipped) supplies power to the foot switch.
With foot switch depressed, test wire 08A out of foot switch to the OCM/SCM.
Then test wire 08B from the OCM to relay 08BCR.
Test wire 08 at 08BCR for power when the relay is activated.
Once these steps are completed and you have power at the correct terminals, you can test the OCM/SCM output for the function or functions you are having a problem with. Activate a function and observe the display – it should show which function is being operated and the percentage value it is currently supplying to the function valve.
By checking the above first, the technician can determine if the OCM/SCM is getting power into it and then putting power out to the switches. This enables the technician to quickly and accurately diagnose a ‘no platform function’ problem.
For more information regarding the OCM/SCM operation and input and output voltages, please consult the service manual for the serial number of the machine you are working on. If you have any questions regarding a Skyjack product, please call Skyjack Product Support at 1-800-275-9522 or email service@skyjack.com
TECH TIDBIT
With the increased use of electronic circuits, the voltages that each circuit requires are more precise than a simpler wire/relay circuit. As a result, a good ground circuit is essential for correct operation. When testing for correct voltages make certain that the ground circuit is good.
