Relays, starter solenoids, fuses, coils

Categories

07/10/2026 27

JCB JS200–JS260 Monitor Messages: What They Mean and What to Check

On JCB JS200, JS210, JS220, JS240 and JS260 tracked excavators with the AMS control system, the monitor in the cab shows the working mode, the time, gauges for oil temperature, coolant temperature and fuel level, and warnings in the message line. Each message first of all points to a real problem: low fuel or coolant, a blocked filter, overheating. But if a message stays on after the cause has been put right, the sensor, wiring or controller is at fault. Below is what each message means and what to check, based on Section C of JCB service manual 9803/6400.

07/10/2026 34

JCB JS200–JS260 Track Tension: How to Check the Sag and Adjust the Tracks

Track tension on the JCB JS200, JS210, JS220, JS240 and JS260 tracked excavators should be checked every shift. With the track raised off the ground, the gap between the underside of the track frame and the top of the track shoe at the fourth bottom roller from the front should be 275–295 mm on hard ground and 320–340 mm on soft sand and sticky clay. Tension is adjusted with grease through the valve on the track adjuster cylinder. The procedure below follows Section 3 of JCB service manual 9803/6400.

07/10/2026 22

JCB 3CX and 4CX Dipper Ram Creep: Causes, Ram Creep Tests and Repair

If the dipper of a JCB 3CX or 4CX backhoe loader drops on its own under load, there are three possible causes: a leaking piston seal in the ram, spool leakage in the excavator valve section, or a leaking auxiliary relief valve (ARV) in that section. The JCB service manual gives a test procedure that identifies the culprit before the ram is removed and stripped. Below are the test sequence, the permitted creep and the repair rules from Section E of service manual 9803/3290.

07/10/2026 29

JCB 3CX and 4CX Hydraulic Oil: HP32 or HP46, System Capacity and Changing the Oil

For the hydraulic system of JCB 3CX and 4CX backhoe loaders, the JCB service manual recommends ISO VG32 oil — JCB Hydraulic Fluid HP32 — at air temperatures below +38 °C. The more viscous ISO VG46, JCB High Performance Hydraulic Oil, is for air temperatures above +38 °C only. Machines with Advanced EasyControl joysticks need a separate all-season HV class oil, JCB Multigrade Anti Shear. The hydraulic system holds approximately 130 litres. The oil is changed every 2000 hours and the filter at every 500-hour service.

07/10/2026 33

JCB 3CX and 4CX Antifreeze: Which Coolant to Use, How Much and How to Change It

On JCB 3CX and 4CX backhoe loaders with the JCB Dieselmax engine, the coolant is renewed every two years, at the 2000-hour service. The cooling system holds 18.5 litres. The JCB service manual calls for an ethylene glycol antifreeze to ASTM D6210 with corrosion inhibitors and rules out organic acid technology (OAT) products. The standard mix is 50%, which gives protection down to −40 °C. Below we cover choosing, checking and changing the antifreeze as described in Section 3 of JCB service manual 9803/3290.

Relays, fuses and coils: 4- and 5-pin relays (12 V and 24 V), a horn relay, starter solenoids (for SB, Perkins and JS starters), hydraulic and transmission valve coils, a front axle lock coil, 40, 50 and 60 A fuses, fuse boxes (including the engine bay box) and a heater resistor.

For relays and coils, check the voltage (12 V or 24 V) and the number of pins. A starter solenoid is matched to the starter model; the engine code is in the name. Starter motors are in starter motors, solenoids in solenoids and valves. For the whole group, see electrical system.

By production type, this category holds: original — 10, OEM — 2, aftermarket — 29. Send JF PARTS the part number and voltage with your price request to speed up part selection.

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