Jaguar XJ40 Window Motor, Windows Not Working
On the XJ40 a dead window is most often the door switch pack, not the motor: its built-in relays click but their tarnished contacts can't pass motor current. When both windows on one side die together, I'd look at the solder joints in the A-post fuse box instead. A motor that clicks with 12 V on it usually just needs freeing and grease.
How bad is it · Safe to drive
Safe to drive; a window stuck open is the worry
Nothing here affects how the car drives. A window stuck down leaves the car open to rain and theft, so tape it up or pull its fuse before leaving the car.
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.
Dirty relay contacts in the door switch pack
Each window is driven by two small relays built into the switch pack in the door armrest. Power for one direction passes through the resting contact of the other relay. Tarnished contacts still show continuity on a meter but can't carry motor current, so the relay clicks and the glass stays put.
You hear a click from the door when you press the switch, but the window doesn't move, or only moves after several tries or a thump on the door panel. Down may still work when up doesn't.
Take the door card off, unplug the motor's two-wire plug (orange/blue and orange/black) and put 12 V straight across the motor. If it runs both ways with the polarity swapped, the motor is fine and the switch pack is the suspect. Don't trust an ohmmeter on the relays.
Lift the pack out, remove the wire clamp screws and prise back the four tabs to open it. Clean both faces of each relay's contacts with contact cleaner on a strip of thin card drawn through while you pinch them shut. If cleaning doesn't hold, fit another switch pack; a used one is the usual source.
Cracked solder joints in the A-post fuse box
The fuses sit on a circuit board in each A-post panel. A cracked or never-soldered joint behind a fuse holder still shows near-normal voltage with no load, then collapses when a motor asks for current. On the XJ40 both right-hand windows share one fuse in the right-hand A-post box, so they die together.
Both windows on one side stop at once, from every switch, with no click and no motor noise. Mirrors and the other side still work. A cheap meter reads fine; a better one shows a low or wandering figure, for example about 10 V at one switch and 4.5 to 6 V at the other.
Check the fuse electrically, not by eye, then measure at the switch pack with the switch pressed. A reading that falls away under load points at the fuse board. Freezer spray on the board can bring a cracked joint back for a moment and show you where it is.
Disconnect the battery in the boot first. Take out the fuse panel (one side screw and the ground nuts), clean any corroded pins and resolder every fuse contact, the ground pin included. The right A-post panel is Jaguar part LMD2827BA if you'd rather fit a used one.
A dry or seized window motor gearbox
The motor and its gearbox sit at the bottom of the door and lose their grease over the years. A motor that clicks with 12 V on its leads is more often stiff than dead, especially on a window that hasn't been used for months.
The relay clicks, the motor hums or gets warm, and the glass doesn't move. Often a rear window that is rarely used, or several windows on a car that has stood.
Put 12 V straight onto the motor at its black PM4 plug, swapping polarity for each direction. Hold the switch and tap the motor housing with a hammer: if it starts, slow and noisy, the gearbox is the problem.
Work it up and down with a dab of bearing grease where the regulator gear meets the motor, until it reaches normal speed. For a proper cure take it out: tape the glass up, undo two 10 mm nuts and four Torx 30 screws, unplug PM4, slide the regulator wheels out of the glass channel and lift the assembly out through the lower opening. Oil the bushes, clean the commutator and brushes and set the armature end-play screw. A used motor is cheap; the front motors swap sides if you move the mounting plate across.
A sticking rocker switch in the driver's master pack
The driver's pack switches every window, and the rocker contacts spread apart with years of use. A contact that stays made keeps driving one window even with nobody touching it.
A rear window lowers itself whenever the ignition is on, or a window goes down and won't come back up. A rocker that doesn't spring back to centre is the giveaway.
If the window runs only with the ignition on, suspect a stuck switch; if it runs with the ignition off, a welded relay. On the rear right door the relay coil is fed on pin 3 of the 6-way yellow plug (black/light green): 12 V there with nothing pressed means welded contacts. To stop it meanwhile, pull that window's fuse or use the child-lock switch on the driver's panel.
A sharp tap on the switch can free it for good. Otherwise open the pack and close the rocker contact arms slightly, watching for small parts that drop out. Two tired packs can be rebuilt into one good one; a used pack is the fallback.
A jammed or bent window regulator
The glass rides on a scissor-type regulator in the door. It seizes after long standing, or a bent arm, a torn door liner or broken motor mounts lock it solid, and the motor stalls.
A clonk and then nothing, the glass rising crooked, or a grinding, rubbing feel. The motor runs or clicks but the glass barely moves.
With the door card off, look for the plastic liner caught in the gears, a scissor arm rubbing the inner door skin, and the rubber-bonded motor mounting studs torn from their metal. A dry, dirty glass channel adds enough drag to stall a weak motor on the way up; clean it and wipe a little lubricant along it.
Soak a seized regulator with penetrating fluid overnight and free it with light taps. Pull a trapped liner clear, and bend a bent arm back with care, or take the regulator out and straighten it. If an arm or flange has broken, fit a used regulator.
A broken wire or bad earth between door and body
Window power runs through the door hinge area and multi-pin plugs, and the relays need a good earth. A feed pulled out of a block connector, or an earth wire broken where it leaves the door, kills a window even when the switch and motor are good.
One window dead with no click while its neighbours work, or the driver's windows and both mirrors dead together. Often after earlier wiring work.
Look at the earth stud over the right A-post fuse panel and the earth wire where it leaves the driver's door. Look at the block connectors in each door for a wire that has pulled out. Measure earth continuity back to the battery negative, ahead of the switch and again at the motor.
Reconnect the loose wire or repair the broken earth. When two windows stop at once, check the shared earth before buying two motors.
No ignition-switched earth to the window relays
The window relays earth through the driver's switch pack to a ground switched by the ignition, on the white/brown wire. Without it every window and the central locking go dead together.
No window works from any switch and the central locking is dead too, while the mirrors still move. The windows need the ignition at least at position I.
With the ignition on, check the white/brown wire at the driver's door pack. Unplug and refit the large plugs on that pack and look for a melted backing. On the driver's pack this is pin 6 of the 6-way yellow plug: it should show earth with the ignition on.
Restore the feed: clean and reseat the plugs and repair the wire. Worth trying before replacing switch packs. Where the wire from the ignition switch is broken, bridging that pin to earth brings every window back, at the cost of windows that work with the ignition off.
The rear isolation switch is off
A small slider between the rear window buttons on the driver's panel stops passengers working the windows. With it off, the passenger windows work only from the driver's seat.
All three passenger windows dead from their own switches, while the driver's pack still moves them.
Look between the rear window buttons on the driver's door for a tiny slider; a white mark showing usually means it's set to lock.
Slide it forward and try again. It's worth trying before anything comes apart.
Switches wet after cleaning the interior
The passenger window switches sit in the trim by the ashtrays. Cleaning fluid or water run into them shorts or gums the contacts, so the passenger windows stop from their own switches.
Passenger windows dead from their own switches straight after the interior was cleaned, while the driver's pack still works them.
Prise the switch out without forcing it; you don't need to take the door card off. Look for damp or sticky residue.
Dry the switches with a hair dryer, or spray them with contact cleaner and leave them a few days.
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.
Check the rear isolation slider
If only the passenger windows are dead from their own switches, look at the small slider on the driver's panel first.
freeListen at the door
A click with no movement points at the relay contacts or the motor. Silence, especially on both windows of one side, points upstream: fuse board, feed or earth.
freeProve the motor with direct power
Door card off, unplug the motor and put 12 V across it, then reverse it. If it runs, the motor is fine; if it's stiff, tap it and grease it.
freeClean the switch pack relays
Open the pack and clean both contact faces on each relay with cleaner on a strip of card. Don't rely on a continuity test.
contact cleanerMeasure under load at the switch pack
Check the fuse electrically and the voltage at the pack while the switch is pressed. If it drops away, resolder the fuse board in the A-post with the battery disconnected.
freeCheck earths and plugs
Ground stud on the right A-post, the earth leaving the driver's door, block connectors in each door, and the ignition-switched feed at the driver's pack.
freeTake out the regulator and motor
Strip, clean and set the motor's end-play, free or straighten the regulator, or fit used parts.
grease, or used partsThe 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, 1993 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.
Circuit descriptions from the Jaguar fuse tables, 1993 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
- Jaguar XJ40 Central Locking Not WorkingIf the locks are dead along with the windows; they share the driver's switch pack.
- Jaguar XJ40 Door Handle Repair, Door Won't OpenWhile the door card is off, if a handle or latch is also playing up.
- Jaguar XJ40 FUSE 1 or FUSE 2 FAIL WarningIf a FUSE message shows on the dash as well.
- XJ6 (XJ40) fuse boxesWhere the A-post fuse boxes sit, other years from the same page.
- 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.