Jaguar XJS Convertible Top Not Working, Pump and Relays
On the XJS convertible a dead top is usually electrical: the console top switch, the top motor relays, or the interlock that wants Park and the handbrake on. An intermittent top often comes down to a corroded earth at the top control module. I'd check the handbrake light and listen for the pump before touching the hydraulics.
How bad is it · Safe to drive
Safe to drive — but a top stuck down leaves the car open
A dead top doesn't affect how the car drives. If it's stuck down, the manual valve on the pump lets you raise it by hand before rain or parking.
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 top switch on the console
The rocker that runs the top lives in the console and its contacts oxidise, especially over a winter of standing. A switch that has gone in one direction leaves the top working one way only.
The top goes down but won't come up, or does nothing at all, with no click or pump sound; often after a long lay-up.
Take the switch out and bridge earth to the up or down wire with a jumper. If the pump runs, the switch is the fault. Swapping in a known-good switch proves the same thing.
Strip and clean the contacts, or fit a new switch. A jumper lets you close the top while the part arrives.
The top motor relays
The pump is switched through relays, one per direction, grouped with the quarter-window relays in the right-hand stowage compartment behind the seats. A failed relay kills the top in its direction even with a good switch.
Dead top, no pump noise, switch already proven good.
Listen for clicks as the switch is pressed. Swap the two centre relays: if the fault moves, you've found it. Measure the up relay's earth to a known good earth — it should read near zero ohms, and it may not share the other relay's earth point.
Fit new relays; ordinary automotive parts work.
A bad earth at the top control module
The module reads the handbrake switch and the gear selector switch as earths. A corroded earth makes the top intermittent: it works one day and needs a dozen presses the next. On earlier cars the module is in the boot near the battery; on 1994-on cars it sits beside the pump.
The top works perfectly sometimes and only after repeated presses at other times.
Before buying switches or relays, check continuity to earth on the handbrake wire and the gear selector wire where they reach the module, and clean the module's own earth.
Clean the module earth contacts; that alone can cure an intermittent top.
The top hangs up on the rear seats: loose rear-window straps
On the 2+2 convertible the rear window frame folds very close to the rear seat backs. Webbing straps riveted to the second crossbar lift the window clear, and when their rivets corrode away the straps hang loose and the frame drags on the seats. Aged, stiff fabric and rear seats refitted out of place eat into the same small margin.
The top stops partway down with the rear window frame or a crossbar against the seat backs, or the seat leather is scuffed; small aluminium plates with rivet stubs turn up loose in the car.
Lower the top halfway and feel between the headlining and the padding for the straps on the second crossbar. Check that the rear seats sit properly in their mounts. TSB 76-124 deals with the same contact.
Re-fix the straps to the crossbar: rivets as the Repair Operations Manual shows, or a loop of 1/8 in welding rod when the rivet stubs are buried under the fabric. With the straps sound, refit the rear seats correctly or ease the seat backs forward. Don't keep running the top with loose straps — it wears through the seat backs.
The interlock — Park or Neutral, handbrake on, and the handbrake switch
The module only runs the top with the ignition at position II, the selector in Park or Neutral, and the handbrake on. If the handbrake warning light stays dark, the module doesn't see the handbrake either, and the top won't move in either direction.
Top dead in both directions and the handbrake light not lit; or a handbrake lever that is seized or only half up.
Slide the leather gaiter up from the back of the lever and bridge the switch's two wires with a test lead. If the light and the top come back, it's the switch. Earthing the handbrake input at the module plug in the boot takes it out of the circuit for a test. To lower the top, both catches at the windscreen header corners must be released too.
Clean the switch posts or replace the switch, and free a sticking handbrake lever.
Low fluid, air in the hydraulics or tired rams
The pump drives two hydraulic rams. Air in the lines makes the top hesitant; rams that no longer hold pressure make it slow, then dead while the pump still runs. A top left still for months can also stick until it has been cycled.
The pump runs but the top slowed over time and now won't move, or is very stiff when moved by hand.
Check the reservoir level and the manual/auto lever position — a lever left in manual stops the electric drive. Run the pump with the reservoir cap loose and watch the fluid move. If the top moves by hand, the rams aren't seized. Before ordering parts, make sure a wet patch in the boot is hydraulic fluid and not rain water. The rams sit behind the rear quarter trim; on facelift cars that trim is held by clips, not screws, and the quarter window should be lowered first.
Worth trying first: lower the top, fill the reservoir to max, then raise it with the cap loose to purge air. Cycle the top once or twice a month. If that fails, overhaul the pump and lines before condemning the rams. Replacement rams that fit 1989-96 cars are available; refill with MIL-PRF-5606H type fluid.
A leaking pump: the motor shaft seal
The pump's electric motor has a lip seal on its shaft. When it fails, fluid weeps out at the pump and the level falls until the top slows and stops. The seal sits on the motor, not on the pump body.
Fluid under the pump in the boot, a reservoir that keeps needing a top-up, and a top that has grown slower.
Look at the pump and the floor beneath it. The pump's harness plug often seizes: penetrating spray in the seams, a small flat screwdriver worked round the edges, warmth and patience will part it — cut and splice a new plug only as a last resort.
Worth trying: a new motor shaft seal (an SKF 527935 has been used) and a top-up with MIL-PRF-5606H type fluid. A pump worn beyond that is rebuilt — the seals on the manual valve can crumble too — or swapped for an exchange unit, HXA8200AA.
No feed — the 30 A fuse or the supply wire
The pump circuit is protected by a 30 A fuse beside the top relays. On Hess & Eisenhardt conversions the pump has its own lead straight from the battery positive, outside the factory harness, and the top and quarter windows share one supply and one earth.
Top and both quarter windows dead together, pump silent, no relay click; often after the battery was disconnected, the car was shipped, or the console was out.
Check the 30 A fuse. Key to accessory: look for 12 V on the brown supply wire, then at the relay, and see whether the relay closes. On an H&E car, trace the extra lead from the battery terminal.
Replace the fuse or reconnect the cut or loose supply lead; that can restore both the top and the quarter windows.
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.
Set the conditions
Ignition at position II, selector in Park or Neutral, handbrake fully on. The handbrake warning light must be lit, or the module won't run the top. The lever only needs to be an inch or two up, provided the light comes on. Release both header catches before lowering.
freeListen and use the boot switch
Press the top switch and listen for relay clicks and the pump. Press the hood switch in the boot: if the quarter windows don't drop, one of the module's inputs is missing.
freeBridge the handbrake switch
Lift the lever gaiter from the back and bridge the switch's two wires. Light and top coming back mean a new switch.
a test leadCheck the 30 A fuse, relays and feed
Check the 30 A fuse and the relays in the right-hand stowage compartment; swap the two centre relays. Look for 12 V on the brown supply wire with the key at accessory.
a multimeterTest the switch with a jumper
Pull the console switch and bridge earth to the up or down wire. Pump running means the switch; clean its contacts or replace it.
a jumper wireClean the module earth
For an intermittent top, check the earth on the handbrake and gear selector wires at the module, and clean the module's earth contacts.
freeSplit hydraulic from electrical on the manual valve
Switch the pump valve to manual and move the top by hand; the Driver's Handbook covers it (pages 77-78 on a 1990 car). Moving by hand with no electrical response points at the electrics; heavy and slow points at fluid or rams.
freeWatch the rear window and check under the pump
If the top stops partway down, watch the rear window frame against the seat backs and feel for loose straps on the second crossbar. Look for fluid under the pump in the boot before bleeding anything.
freeBleed the hydraulics, then look at the rams
Top down, reservoir to max, raise with the cap loose to purge air. Only if the pump runs and the top still won't move do the rams come into question.
fluid; rams if neededThe 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.
We have no drawing of this box for this car — find them on the legend printed on the lid of the box itself.
What it usually isn't
Don't spend money here first:
If none of this finds it:
On jagaux.com
- Jaguar XJS Window Motor, Windows Slow or Not WorkingIf only the rear quarter windows misbehave — their motors and gearboxes.
- Jaguar XJS Electrical Problems, Bad EarthsCorroded earths behind other failures too.
- XJS fuse boxes and relaysWhere the fuse boxes and relays 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.