Jaguar XJ40 FUSE 1 or FUSE 2 FAIL Warning
FUSE 1, FUSE 2 or FUSE 3 names the fuse box, not a fuse: 1 is the right-hand door pillar box, 2 the left-hand, 3 the centre armrest. The cause is usually a fuse that looks good but doesn't conduct, a cracked solder joint behind the box, or a load that keeps blowing its fuse. I'd start with a test lamp on both blades of every fuse in the named box.
How bad is it · Safe to drive
Usually safe to drive — but don't fit a bigger fuse
The car normally drives with the warning on, but a poor contact behind a fuse runs hot and can melt the box, and a cracked joint can take out the whole dashboard and the starter. A fuse that blows again is protecting a fault — a larger one only moves the damage.
Which one applies to yours depends on your symptoms, your model year and what has already been done to it.
Likely causes, most common first
Read the check cost before the odds: a free check that rules a cause out beats a likely guess that costs money.
A fuse that looks good — even measures good — but doesn't conduct
The monitor sees voltage on one side of a fuse and none on the other. A fuse can break at the corner of its element, or corrode at the blades, and still look intact; an ohmmeter out of the box can't show how it seats.
The warning came on after work near the fuses or a bump. On some cars an empty spare-fuse slot can trigger it. The cooling-fan fuse is a frequent one: a weak grip on its blades heats up under load, and the monitor reads the drop as a failed fuse.
Ignition on, 12 V test lamp from ground to both blades of every fuse in the named box. Lit on one side only: a bad fuse. Dark on both: a supply or board problem. If everything that fuse feeds still works, suspect the monitoring board rather than the circuit.
A new fuse, or cleaned blades. Check for a loose power wire on an in-line fuse too, such as the ABS one. The warning clears by itself once the fault is gone. Coat cleaned blades with dielectric grease; just pulling and reseating a fuse can clear it for a while.
A cracked solder joint on the board behind the fuse box
Each box is a circuit board carrying the monitoring parts. Heat and vibration crack the joints on its back, often too finely to see without a loupe; pulling a fuse can flex one open.
The warning comes and goes with heat, hot-idle fans or bumps, every fuse tests good, and circuits die in groups. On 1993–94 cars, water getting into the box through a rusty inner wing does the same — the left-hand box on a right-hand-drive car, the right-hand one on a left-hand-drive car.
Battery off, box out, inspect the back under magnification. Have the radio code ready. While it's out, check the plugs on the back of the box for loose or corroded pins.
Resolder the joints with fresh solder, not just reflowed — or fit a used box.
The relay module on 1993–94 cars (DBC10009): same fault, different box
On the last two model years the relays under the passenger knee roll became black modules. Their relay legs crack their solder joints, and unrelated circuits on one module die together.
Radio, blower and air conditioning drop out together, or every sidelight goes with a bulb-failure warning; often after standing.
Trace the dead circuits to the module, open it and look at the relay joints.
Resolder the relay joints with fresh solder. A used module can have the same bad joints. Dirty relay pins do the same: pull every relay pack behind the knee bolster and clean the contacts before buying a module.
A genuine short that keeps blowing the fuse
If the new fuse blows too, the fault is in what it feeds. Fit a fuse, then switch the circuit's items on one at a time.
It blows the instant something is switched on — air conditioning, the starter — or as soon as it's fitted. A fuse that blows the instant the A/C fan is switched on points at the compressor clutch, its wiring or the auxiliary cooling fan, which share one fuse. One blown logic fuse can kill the radio, the dash lights and the starter together and look like an immobiliser fault. An aftermarket radio on a small 3 A fuse can blow it on the move.
Unplug the loads one by one. Meter heater elements and compressor clutches; look for spliced or mismatched connectors. For the fan and clutch fuse: unplug the single wire to the compressor clutch — the coil should read about 2.8–4.4 ohms — and spin the auxiliary fan by hand; a seized compressor burns its belt rather than blowing the fuse. With the fuse out and the battery connected, the supply side should show 12 V and the load side no continuity to ground; continuity there means a short — pull the relays on that fuse one at a time to find the branch.
Replace the shorted part — for example the crankcase breather heater, the A/C clutch coil, the cigar lighter, or the ignition relay if it blows only when cranking.
The wrong fuse in the slot: undersized, uprated, or a cheap one
Thirty years of hands in the boxes leave fuses of the wrong value behind. Too small, and it blows under normal load; too big, and the wiring becomes the fuse. Cheap fuses can also hold well past the printed rating.
A fuse that blows on a circuit with nothing wrong in it; a rating in the box that differs from the chart; a window or a relay circuit that works again with the right fuse. A legend that doesn't match the fuses in the box — an interior or box taken from another car brings its own chart.
Compare every fuse with the chart for your year — the label on the box doesn't always list everything a fuse feeds. While hunting a fault, use a resettable circuit breaker of the right rating instead of a stack of fuses. The lists differ by model year.
Fit the correct value, preferably a name-brand fuse, and treat the corroded blades at the same time. Never fit a bigger one to stop it blowing.
A whole box dead: the ignition-on relay that feeds it
The centre fuse panel, and with it the instrument pack, takes its ignition feed through the ignition-on relay behind the radio rather than straight from the switch. When its contacts go bad, every fuse it feeds is dark on both blades and a whole group of circuits dies together.
Ignition, instruments and starter dead together with no blown fuse; things coming back for a moment when the relay is touched.
Ignition on, test lamp on both blades: dark everywhere in one box means look upstream. Pull the ignition-on relay; de-energised, there should be no continuity between terminals 30 and 87.
Clean the relay contacts or fit a new relay.
An in-line fuse behind the knee bolster: the wiper park fuse
Some circuits are protected by in-line fuses outside the three boxes, behind the knee bolsters. The wiper park fuse blows whenever the wiper is switched on with the blade frozen to the glass — it was added partway through production to save the park motor.
The wipers stop parking, often after a frosty morning, and every fuse in the three boxes tests good.
Take the knee bolster off and test the in-line fuses. The park fuse was 7.5 A at first and 10 A from about the 1991 model year; 1993–94 cars have no in-line wiper fuse.
A new fuse of the right rating. If it blows without frost, the wiper motor or its gearbox is drawing too much current — inspect it before buying a new one. Lift the blades off the glass before a hard frost.
A monitored slot for equipment the car doesn't have
The monitor watches slots, not equipment. A fuse missing from a slot whose system was removed or never fitted can trigger the warning.
Every circuit works, and the warning persists.
Compare the box with the fuse chart and fill every slot it lists, including the spare.
Worth trying; no proven cure yet.
The order to check them in
The point of the order is money: each step either rules a cause out or makes the next one worth doing. Green is free, amber costs a little, red is the one to arrive at last.
Read the number as a box
FUSE 1 — right-hand pillar box, FUSE 2 — left-hand, FUSE 3 — centre armrest. Not sure which is which? Pull a fuse from one box and switch on: the number that comes up names that box.
freeTest every fuse in that box live, both blades
Ignition on, lamp to ground. Replace any fuse live on one side only; clean the others' blades.
a test lampThen the in-line fuses behind the knee bolsters
The wiper park fuse lives there on most cars before 1993.
freeFill every slot, including the spare
Check against the fuse chart for your year.
freeIf a new fuse blows, isolate the load
Switch the circuit's items on one at a time; never fit a larger fuse. A resettable breaker of the same rating saves fuses while you look.
freeIntermittent, heat- or bump-related? Resolder the board
Battery off first. Fresh solder on the named box — or on the relay module, if the dead circuits share one.
free with an ironThe fuses named above — where they sit
The highlighted position is the one the procedure talks about. Pulling a fuse is a stop-gap, never a repair: check what the circuit feeds before you pull it.
Circuit descriptions from the Jaguar fuse tables, 1990 edition. Drawing by jagaux.com from the factory electrical guide. Fuse layouts change between model years — read the legend on the lid of your own box before pulling anything.
What it usually isn't
Don't spend money here first:
If none of this finds it:
On jagaux.com
- XJ6 (XJ40) fuse boxesWhat every fuse in each box feeds — other years from the same page.
- Jaguar XJ40 Air Conditioning ProblemsIf the fuses are fine but the A/C still blows warm.
- Jaguar XJ40 Blower Motor Not WorkingIf a heater blower is dead with its fuse looking good.
- Jaguar XJ40 Headlights Not WorkingIf a headlamp is dead or dim and its fuse tests good.
- Jaguar XJ40 Dashboard Warning LightsIf the VCM shows PAD or FAIL, or the gauges and panel lights are the problem.
- Jaguar XJ40 ABS and Brake Accumulator ProblemsIf the VCM shows ANTI LOCK FAILURE, FAIL or Low Brake Pressure rather than a fuse box.
- Jaguar XJ40 Bulb Failure WarningIf the bulb-failure symbol shows rather than a fuse warning.
- Jaguar XJ40 Central Locking Not WorkingIf the door-lock fuse keeps blowing and the central locking is dead.
- Jaguar VIN decoderConfirm your exact model year, engine and factory options before ordering parts — free.
Ratings, fuse numbers and torque figures vary by model year and market. Read the legend on your own car before pulling anything, and use the figures in the manual for your car, not the ones in a video.
Check your VIN: exactly which car you have and which bulletins apply to it.