Skyjack SJIII4740 Service & Repair — Chicagoland | Win Win Equipment
Same-day diagnosis in Addison, IL · 40 ft class · GP-102 flash codes · Repairs $150/hr · Annual ANSI inspection $225
The SJIII 4740 (SJIII4740, or just SJ4740) is Skyjack’s 40-foot-class wide-deck — a 7,500-pound machine that earns its keep in distribution centers and high-bay work. We repair, inspect, and refurbish them at our Addison, IL shop. We pick yours up and diagnose it the same day; straightforward fixes go back the next day, and complex problems get an honest timeline before any work starts. Call 773-790-7299.
SJIII4740 quick service specs
From Skyjack’s service manual (P/N 196430) for covered serial ranges:
| Battery pack | 4 × 12V (US XC2; AGM option) — unlike the 6V packs on smaller SJIIIs |
| Hydraulic oil | ATF Dexron III (bio-oil option) · tank 7.4 gal |
| Brake hub oil | SAE 20W, 180 mL — a spec most owners never learn until it matters |
| Tires | 16 × 5 × 12 solid rubber |
| Machine weight | ~7,500 lbs (standard extension; check nameplate) |
| Platform capacity | 500 lbs / 2 persons (ANSI) · extension deck 250 lbs |
| Lift / lower time | 67–76 sec up; 46–54 sec down (load-dependent) |
| Key torques | Wheel motor hub & brake hub 350 lb-ft · wheel bolts 90 lb-ft · castle nut 150 lb-ft (factory procedure) |
| Overall width / length | 47.1 in / 94.7 in |
| Platform size (inside) | 41.7 × 86.1 in |
| Working height | ~45 ft (13.82 m) · platform 38 ft 9 in (11.82 m) |
The one SJIII that actually flashes codes at you
Most SJIII machines are pure analog — no codes anywhere. The SJIII4740 is the exception: its GP-102 load-sensing controller reports problems as LED flash sequences (first digit, pause, second digit; long pause; repeat). If your 4740 refuses to lift or drive and an LED is blinking at you, count the flashes:
| Flash code | What the controller is saying |
|---|---|
| 1 | Vehicle tilted — off-level; move to flat ground |
| 1 / 2 | Vehicle overloaded — reduce platform load |
| 1 / 3 | Armguard active |
| 1 / 4 | Too high — drive prevented |
| 1 / 5 | Too high — lift up prevented |
| 2 / 2 | Elevation switch stuck |
| 5 / 1 | B+ supply too low — check batteries and connections first |
| 5 / 4 | Up/down select inputs active together — switch or wiring fault |
| 5 / 5 | Waiting for neutral — release the joystick, check its neutral switch |
| 6 / 1 | Height not calibrated |
| 6 / 2 | Load not calibrated |
| 6 / 4 | Invalid load — check load sensors |
| 6 / 5 | Invalid height — check height sensor |
| 6 / 6 | Overload functions disabled |
| 7 / 1 | Bad tilt sensor — replacement job |
Counting something different, or a wiring-level code (the 4/x series)? Call 773-790-7299 with the flash count and serial number — calibration codes (6/1, 6/2) in particular need the factory procedure with a known weight, which is shop work.
Everything else: troubleshooting by symptom
Completely dead: charger cord still plugged in (interlock — the most common call), battery disconnect, terminals, battery condition across all four 12V blocks, fuse F1, breaker CB2, both e-stops, key switch — the factory ladder, in that order.
No drive or steer while elevated: pothole protection bars first — debris or bent linkage holds the limit switches open by design.
Drifts down: on the 4740 the lift cylinders run wear rings rather than piston seals — drift points to the gland seals or the twin holding valves and lowering-valve stack. Shop diagnosis, quoted first.
No emergency down: the 4740 has a dedicated factory ladder for this one — and it’s the failure you want fixed before someone’s stuck at 40 feet. If emergency lowering is dead, park the machine and call.
Annual inspection, pricing, and the honest math
Skyjack’s decal rule: no recorded inspection in 13 months = don’t use the machine. Annual ANSI/OSHA inspection — $225 in-shop, $350 on-site across Chicagoland, same-day certificate pre-scheduled, renewal reminders included. Repairs $150/hr plus parts, quoted after same-day diagnosis. If the estimate crosses roughly half the machine’s value, we’ll show you a refurbished SJIII4740 with a fresh inspection on it.
SJIII4740 flashing a code? Same-day diagnosis.
Call 773-790-7299 or request service.
SJIII4740 service FAQ
What batteries does an SJIII4740 take?
Four 12-volt batteries (US XC2 flooded standard, AGM option) — different from the 6V packs in smaller SJIIIs. Charger must match the battery type. We install Crown deep-cycle batteries to this spec — a US-built pack that outlasts the cheap imports.
My 4740’s LED is flashing — what does it mean?
That’s the GP-102 load-sensing controller. Count first digit / pause / second digit and check the table above — tilt (1), overload (1/2), and low battery (5/1) cover most of them.
What oil and how much?
ATF Dexron III, 7.4-gallon tank — plus SAE 20W in each brake hub (180 mL), which is the one everyone forgets.
SJIII4740 or Genie GS-4047?
The 40-ft rivals — we sell and service both: honest side-by-side here.
Spec, flash-code and troubleshooting data: Skyjack Service & Maintenance Manual P/N 196430 (SJIII 4740, covered serial ranges). Trademarks belong to their owners; Win Win Equipment is an independent service shop.
Get your SJIII4740 fixed: call 773-790-7299 (Mon–Fri 7am–3pm) or request service online. Also see: service hub · Skyjack service · GS-4047 service · annual inspection.