JLG Scissor Lift 662 Fault Code: CAN Bus Failure - Platform Module
Also called Communications - CAN Bus Failure - Platform Module
CAN Bus Failure - Platform Module · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault 662 sets when JLG's control system, running in platform mode, stops receiving CAN bus messages from the platform module for 250 msec. It signals a communication break somewhere between the ground board, arm stack harness, power module, and platform board.
High severity. This fault disables normal platform-mode operation and is flagged by JLG as machine system distress. The machine should not be relied on for lift operations until CAN communication with the platform module is restored.
What does JLG Scissor Lift error code 662 mean?
Fault code 662 means that while the machine is in platform mode, the control system (referred to as the UGM) failed to receive expected CAN bus messages from the platform module. The CAN bus is the digital communication network that lets the ground controls, power module, and platform controls talk to each other. When that link drops, the platform loses its ability to reliably send commands and status information.
JLG classifies this as an indicator of machine system distress. When it is active, the control system disregards any CAN messages that claim to come from the platform module's source addresses, since it cannot trust that the link is intact.
This code is closely related to fault 661. Several of the diagnostic steps for 662 depend on whether 661 is also present, since both codes point to breaks in the same CAN wiring path between the platform box, arm stack harness, ground board, and power module.
What triggers a JLG Scissor Lift 662 code?
The platform option must be configured as enabled and a platform detected as attached. Under those conditions, if the UGM does not detect the platform module on the CAN bus for a period of 250 msec, fault 662 sets. The fault latches until the machine is power cycled.
Common causes of 662
- Open or damaged wiring in the CAN bus circuit between the platform box connector and the ground board connector (terminals A and D, and ground board sockets J1-6 and J1-7)
- A fault in the arm stack pass-thru harness, including open or shorted CAN wiring or an out-of-spec termination resistor between pass-thru sockets 5 and 6
- Damaged or open wiring between the arm stack pass-thru connector and the ground board J1 connector (pins 5, 6, 7 to J1-11, J1-12, J1-13)
- A wiring fault between the ground board J1 connector and the power module connector (J1-31, J1-32 to power module sockets 10 and 11)
- A failed power module
- A failed ground board, especially if both 661 and 662 remain present through all wiring checks
- A failed platform board or bad wiring inside the platform box (platform box sockets E and F to platform board J1-3 and J1-4)
How to troubleshoot JLG Scissor Lift 662: first checks
- Turn the machine on in ground mode and check whether DTC 661 is also present, since this determines which branch of the diagnostic checks to follow
- With no 661 present, check for 24V between platform box connector terminals D and A, then verify continuity from those terminals back to ground board connector sockets J1-6 and J1-7
- With 661 present, disconnect the arm stack pass-thru connector near the ladder on the left side and recheck in ground mode to isolate whether the problem is in the arm stack harness
- Inspect the arm stack pass-thru harness continuity and resistance values, including the 120 Ohms +/- 5% termination resistor check between pass-thru sockets 5 and 6
- Check continuity between the arm stack pass-thru connector and ground board J1 pins 11, 12, and 13, confirming no shorts exist between those CAN signal pins
- Check continuity between ground board J1 sockets 31 and 32 and power module connector sockets 10 and 11, confirming no shorts between 31, 32, and 33
- With all prior connections reconnected, disconnect the power module connector and power up in platform mode; if 662 clears, replace the power module
- If 661 and 662 persist through all wiring and power module checks, replace the ground board
- Open the platform box and check continuity between platform box sockets E and F and platform board J1-3 and J1-4; if these check out fine, replace the platform board
How the code clears
Fault 662 latches until the machine is power cycled. There is no separate reset procedure beyond correcting the wiring or component fault causing the CAN communication loss and then cycling machine power. Simply clearing the fault without repairing the underlying open circuit, bad connector, or failed board will allow it to reset as soon as platform mode is engaged again.
Frequently asked questions
What does JLG fault code 662 mean?
It means the control system, while in platform mode, lost CAN bus communication with the platform module for 250 msec or more, with the platform option enabled and a platform detected as attached.
Is fault 662 related to fault 661?
Yes. JLG's diagnostic steps for 662 branch depending on whether 661 is also present, since both codes point to failures in the same CAN wiring path connecting the platform box, arm stack harness, ground board, and power module.
Can I clear fault 662 by just cycling the key?
The fault does latch until a power cycle, but if the underlying wiring, connector, or board problem is not fixed, the fault will simply return once platform mode is engaged again.
What parts are most commonly replaced for fault 662?
Depending on where the wiring checks fail, technicians may end up replacing the power module, the ground board, or the platform board. Most cases, though, trace back to a wiring or connector problem rather than a failed board.
Is it safe to operate the lift with fault 662 active?
No. JLG lists this as an indicator of machine system distress affecting platform mode communication. The platform controls should not be trusted until CAN communication with the platform module is confirmed restored.
Where should I start troubleshooting fault 662?
Start in ground mode and check whether fault 661 is also present. That determines whether you begin checking the platform box to ground board wiring directly, or first isolate the arm stack pass-thru harness by disconnecting it near the ladder.