JLG ES series scissor lifts (1930ES, 2030ES, 2630ES, 2646ES, 3246ES)
JLG error code 321 — LINE CONTACTOR MISWIRED ON OR WELDED
Message on the display: LINE CONTACTOR MISWIRED ON OR WELDED
Code 321 occurs in machines: JLG ES series, 1932RS, 6RS, 3248RS, 10RS, 4045R, R4045.
blocking fault
Battery voltage was present at the power module B+ terminal at power up. Drive, steer and lift up prevented.
Description from the JLG service manual, in the original wording.
Possible causes
The manual does not list the causes for this code: the service technician establishes them during diagnosis of the machine.
Checks from the manual
- Check wiring of contactor.
- Check resistance between the studs of the contactor while disconnected from the machine.
- Check contactor main contact wiring to battery (+) terminal and power module terminal B+.
- Check continuity between contactor connector pin 1 and ground board socket J1-19.
- Check continuity between contactor connector pin 2 and power module 12 position connector terminal 8.
- Measure voltage between power model B+ and B- terminals. If 24V is present, replace line contactor.
- Replace power module.
What service does
A qualified service technician reads the code with the manufacturer's diagnostic tools, finds the cause, clears the code and carries out a function test.
Source: JLG Service and Maintenance Manual, ES series (Diagnostic Trouble Codes section).
The descriptions are quoted from the manufacturer's service documentation and are for guidance only. Clearing codes, calibrations and repairs are carried out by a qualified service technician according to the manual for the specific serial number. A machine with an active blocking code must not be used until the cause has been removed.
Does code 321 not go away?
RK Rental services JLG lifts at our workshop or on site at the customer's premises (construction site, factory, warehouse). We read the code, remove the cause and select the parts by serial number.