JLG ES series scissor lifts (1930ES, 2030ES, 2630ES, 2646ES, 3246ES)
JLG error code 7742 — FIELD VOLTAGE IMPROPER
Message on the display: FIELD VOLTAGE IMPROPER
Code 7742 occurs in machines: JLG ES series, 1932RS, 6RS, 3248RS, 10RS.
blocking fault
Drive, Steer, and Lift 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
- The System Module voltage at the F1 and F2 terminals was improper at power-up (expected to be ½ Battery Voltage). This is caused by an open- or short-circuit in the field wiring or motor. Disconnect the field and motor wiring from the System Module and connect F1 / F2 with a short wire. If the situation persists after a power cycle, it may be an internal issue.
- ZAPI - HEALTH (Status LED) - ON
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 7742 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.