Jaguar XJS Power Antenna Stuck
Before buying a new aerial, feed its motor straight from 12 V. If it runs, the fault is upstream: the board inside the aerial, a hidden in-line fuse, the delay relay, the wiring — or, on a 1994 car, simply an open boot lid. If the motor turns but the mast won't move, it's the mast or its drive, and both are cheap to replace.
How bad is it · Safe to drive
Safe to drive
Reception suffers and a mast left up can be snapped in a car wash. If the aerial motor keeps running with the car off, it also flattens the battery — see the battery page.
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 control board inside the aerial
Earlier Hirschmann aerials carry a small board in the top of the motor housing that decides direction and when to stop. Water down the mast reaches it despite the sealed motor, and corrosion or one burnt part stops everything while the motor itself stays healthy.
The mast slides freely and the motor runs both ways on a direct feed, but not through the car's wiring, though supply and up signal are right at the plug.
Open the top and look for corrosion, black deposits, a cracked diode or a part running hot. On the Hirschmann board, with the gap between spades 4 and 5, they read 1 Brown, 2 Blue, 3 Red, 4 Green, 5 Black; Red and Green are the motor. Put 12 V across those two and then reverse it — a motor that runs both ways on its own but not through the board means the board is bad.
Replace a shorted or snapped diode — a part for under two dollars — or plug in a used board that tests good, or one from a scrap aerial of the same make (the same boards went into several German cars). Past saving, a generic power aerial does the same job.
A bent, dirty or dry mast
The telescopic mast drags when a section is bent — a car wash with the aerial up is the classic way — or when grit and dried grease build up. Even a slight bend at the base can stop the last half inch of travel.
The motor runs, but the mast is sluggish, stops short of home, won't come up, or moves in jerks.
Undo the collar nut on the wing, switch the radio on and ease the mast out as it rises, noting which way the nylon teeth face. Straight and free-sliding goes back in the same way; bent or gritty means a new mast.
Graphite on the sections is worth trying first; cleaning and straightening only buy time. A new mast is the lasting cure and an easy job: radio on, feed the toothed cable down about two feet until the motor catches it, then switch off and let it draw the mast in.
A broken drive cable or a worn motor
A toothed plastic cable on a spool drives the mast; inside the housing a tiny toothed belt or a nylon drive wheel turns the spool. They snap or strip, especially if a stuck mast was forced down, and the motor spins without moving anything.
The motor runs with the radio but the mast stays put or goes part-way; or it sounds rough after being pushed down. A silent motor on a good feed is the motor itself. A mast stuck up that can't be pushed in by hand can be a kink in the drive cable.
Feed the motor directly from 12 V, relay out of circuit. If it still misbehaves, relay and radio are cleared. Open the housing and look for a broken belt, a snapped finger on the drive wheel, or old cable jammed inside.
With the motor turning and only the plastic cable gone, a new mast feeds in from outside. The internal belt is 5.6 mm wide, 125 mm long, 2 mm pitch; a lost finger on the drive wheel can be replaced with a short bolt. A new motor is about $200, so a universal aerial at about $30–50 is the usual answer — it fits, drain tube and all. The original rear Hirschmann unit for 1986–91 cars is DAC3579, and used ones turn up. Or give up the mast: a stick-on window aerial costs very little and does most of the job, but it hears less and picks up more interference.
A hidden in-line fuse in the boot
The motor has its own 10 A in-line fuse besides the main-panel fuse shared with the boot lamps. On pre-facelift cars it sits just ahead of the unit, behind a reinforcing channel in the wing, and diagrams often miss it. Early cars add a small 2 A fuse on the radio side — on an 1984 car it is buried in the gear-selector console.
The aerial works on direct 12 V and the radio's signal reaches the plug, but the permanent feed is missing — while the boot lamps work.
Follow the wiring forward from the unit inside the wing, about a foot, for an in-line holder; on a 1990 convertible it sits in the right of the boot by the relay, on a 1994 car under the wing above the aerial. Some cars hide one more behind the radio. Test with a test lamp, not by eye.
Replace the blown fuse; the delay relay can stay. On 1994 cars there is no fuse between radio and aerial — if that line is dead, look at the boot lid first.
An open boot lid on 1994 cars
On 1994 cars up to VIN 190529 an override relay sits between radio and aerial alongside the delay relay. It keeps the mast down while the boot is open, so it can't strike the lid or the spoiler; spoiler cars drop the aerial as the boot opens.
The motor feed from the fuse box is live, but the radio's signal line shows zero and has no fuse to find.
Shut the boot and try the radio again before chasing fuses. Then open the boot with the mast up — it should drop.
Nothing to repair: with the boot shut the aerial works, engine running or not. Later 1994 cars have neither relay and no in-line fuse on that line.
Wiring upset by a new radio or aerial
The factory radio's switched signal works a relay or the aerial's own board, not the motor. Many aftermarket radios' aerial leads can't drive it, generic aerials use their own colours, and three wires are easy to cross.
Trouble started with a new radio or aerial; it goes up but not down, runs backwards — down with the radio on — or does nothing with 12 V on the radio's aerial lead.
The motor feed should be live all the time and the sense lead only with the radio on. On 1994–95 cars purple is the constant feed, black earth, white/orange the relay-switched drive that raises the mast, yellow/green the radio's trigger to the relay; on 1992–93 cars red is constant, black earth, white the sense line. Bench-test a cheap aerial on 12 V first.
Rewire it that way; if it runs backwards, swap the two drive wires. If the radio's aerial lead won't trigger it, use the amplifier-remote lead or a small transistor. Check before powering up — a botched aerial install can burn out the factory radio.
The green delay relay
On pre-facelift cars a green relay-and-timer in the boot switches both motor wires and holds retraction back about 15 seconds, so the mast doesn't cycle when the radio is flicked off and on. Its contacts pit and stick closed.
The aerial keeps running or won't retract, then drops after a bump or a knock on the relay. On 1994 coupes it's a small can on the aerial frame. Its job is to keep the mast clear of the boot lid; on some cars the can is purple rather than green.
Ignition on, radio off, aerial unplugged: 12 V on relay pin 2 means it's stuck; if not, check pin 1 for a good earth. Or swap in a known good relay, or bypass it and feed the motor directly. If the mast moves at all, the relay is switching.
Worth trying: lift the green cover and clean the contacts, or fit a replacement — the Series 3 XJ6 used the same relay, so scrap cars are a source; avoid ones that sat in water. Many generic aerials time themselves, and then the relay can go.
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 in the boot
Trim back, radio on and off. A turning motor with a still mast points at the mast or its drive; silence points at the feed, relay or motor.
freeShut the boot lid
On 1994 cars the aerial won't rise with the boot open. Test with it closed.
freeFeed the motor straight from 12 V
Runs: the fault is upstream. Doesn't, or grinds: cable, belt or motor.
freeFind the in-line fuses
The 10 A motor fuse in the wing, just ahead of the aerial on pre-facelift cars; the main-panel fuse shared with the boot lamps; on early cars a 2 A fuse in the console.
a fuseTry another delay relay
Or clean its contacts, or bypass it for a test.
a used relayPull the mast and look at it
Collar nut off, radio on, ease it out. Bent or gritty: a new mast.
about $20 for a mastOpen the aerial and look at its board
Look for corrosion, a burnt diode, a hot spot. Then renew the rubber grommet on the wing: it sits at an angle, thick end rearwards at about 4–5 o'clock, and a wedge-shaped PCV-valve grommet will do if the original can't be had.
free to a few dollarsOnly then a new aerial
Universal aerials fit and are reached easily from the boot; connect a drain hose to the bottom outlet, or rain kills it within a few years. An old car's odd coax plug is swapped for a standard crimp-type Motorola connector. Late convertibles with a rear spoiler use a faster aerial that retracts when the boot opens.
about $30–50 universalWhat it usually isn't
Don't spend money here first:
If none of this finds it:
On jagaux.com
- Jaguar XJS Battery DrainAn aerial that keeps running after switch-off is the most common drain on these cars.
- XJS fuse boxes
- XJS 1994 radio pinout and wire coloursIncludes the aerial lead; drawn for the 1994 car, earlier XJS wiring differs.
- Jaguar XJS Window Motor, Windows Slow or Not WorkingIf the windows are slow or dead too — the same direct 12 V motor test.
- 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.