Jaguar XJ8 (X308) Antenna Stuck or FM Ticking
On these cars a stuck aerial is rarely the motor. I'd look at a snapped plastic drive tape with a piece left inside, or a bent or seized mast — each fixed from the top or on the bench. FM ticking that follows the engine isn't the radio either: look at the coil tips.
How bad is it · Safe to drive
Safe to drive — nothing to do with the car's health
A mast left up is easily bent by a car wash or garage door. The ticking points at an ignition coil, worth a look for the engine's sake too.
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.
The plastic drive tape has snapped — and a piece is still inside
A toothed nylon tape on a reel in the boot unit drives the mast. When it snaps, the broken piece stays on the reel and fills the space the new tape needs, so a new mast won't go fully down.
The mast won't retract, or stops short of the last section, while the motor hums and stops.
Lay the old tape next to the new one. If the old one is shorter, the rest is inside. Look at the end of the old tape too: if a bit is missing, it is still inside.
Take the unit out, split the housing carefully, remove the piece, clean and grease, then feed in the new mast on the retract cycle.
A worn or bent mast — replace it from the top
The motor stops on resistance at each end, not on switches. A bent or worn mast drags, so it stops half-way or won't extend fully.
The mast has been bent, or stops at the same point every time the radio goes off.
Look at the mast for bends and wear with it fully extended.
A new mast of the right length; genuine is safest, as some cheap ones fail within weeks or fit badly, though a good aftermarket one receives as well. Undo the top nut (it may just spin in its grommet) and pull it upward; radio on to drive the old mast out, note which way the teeth face, feed the new tape in the same way, radio off to draw it down. If the part is dear or scarce, a whole used or aftermarket unit can cost less than the mast alone. A slightly bent mast can be straightened.
A mast seized in its sleeve
Dirt and water collect at the bottom of the unit when the drain tube blocks. The mast corrodes into its sleeve and won't come out from the top.
The old mast moves only a fraction of an inch however hard you pull; the drain tube under the unit is clogged.
Don't pull with grips — small feet hold the sleeve. Take the unit out, remove the cover, withdraw the mast from below.
Clean the sleeve and clear the drain; if it won't free, a used complete unit. Afterwards, wipe the extended mast clean rather than oiling it.
FM ticks in time with the engine — a corroded coil tip
Each plug has its own coil. Corrosion on a coil's tip where it meets the plug makes it arc, and the radio hears every spark.
A rhythmic tick on FM that speeds up with revs, often after a plug change or an engine wash.
Pull each coil and look at its tip. Check the bonnet earth strap near the left hinge too — it's there to screen interference and corrodes.
Clean the corroded tip and dry the coil wells; new plugs alone won't cure it.
The mast freezes in hard frost
Water and slush on the mast turn to ice in the sleeve, and the motor can't break it free, so the mast sticks up or down until it thaws.
Only in freezing weather, often after driving on snowy roads; fine again once warm.
See whether the fault goes away when the car has warmed up in a garage.
For the winter, park the aerial: take off the right-hand trim panel in the boot and unplug the small two-wire connector at the unit — no cutting, the mast stays where it is, plug it back in spring. A thin oil that doesn't thicken in the cold helps but needs frequent top-ups.
Aerial dead or drops by itself — supply, control wire or radio
The aerial has three wires: permanent 12 V, earth and an up-down signal from the radio. A missing supply or a failed radio output leaves a healthy motor silent; lose the up signal on the move and the mast goes down on its own. On premium systems a disconnected supply wire can even kill the radio's sound.
No hum at all when the radio goes on or off; sometimes the radio tunes but plays only faint static.
Check for 12 V at the aerial plug. Then feed 12 V to the control wire through about 1 kilohm: the mast should rise, and fall when removed. If it does, the fault is in the radio or its lead.
Worth checking first: a supply plug disconnected in the boot, and the wiring where it passes the boot-lid hinge, where it can be pinched and cut. Otherwise, resolder the radio's aerial output.
Crackly reception — the aerial connections
Corroded or loose aerial joints and a dirty aerial earth let noise in on both bands.
Crackle on FM even with the mast fully up.
Clean the aerial earth, then unplug and reseat each aerial connection, starting at the back of the radio.
Worth trying: reseating the joints, the one at the radio first.
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.
Listen for the motor
A hum with no movement points to the tape or mast; silence, to the supply, control wire or radio.
freeSwap the mast from the top
Nut off, radio on to drive the old one out, new tape in with the teeth facing the same way, radio off. Compare old and new tape lengths; if the new mast won't pass the nut, a touch of filing may be needed.
a genuine mastShort tape or seized mast: unit out
From the boot, a few screws on the cover. Keep the steel washer under the large gear. Clear the drain tube.
free, an hourTicking with revs: coils first
Clean every coil tip, dry the wells, check the bonnet earth strap.
freeKeep it clean
Wipe the extended mast now and then; heavy oil attracts dirt. If it keeps freezing in winter, unplug it for the season behind the right-hand boot trim.
freeWhat it usually isn't
Don't spend money here first:
On jagaux.com
- XJ8 (X308) fuse boxesIf the aerial is completely silent, check its supply first.
- XJ8 1998–1999 radio pinout and wire colours
- XJ8 2000–2003 radio pinout and wire colours
- Jaguar radio code generatorFree. For the X308 factory radio, if it asks for its code after the battery or radio has been disconnected.
- 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.