Jaguar S-Type Rear Light and Brake Light Problems
On the S-Type, a rear light that goes dim or dead on one side is most often a blown 10 A fuse in the luggage compartment fuse box, even when the fuse was looked at once already. The lamps take a permanent feed and the rear module switches their earth, so a dead fuse can still leave a faint glow that looks like a wiring or module fault. I'd test both rear fuses for that side with a meter before buying a cluster or a module.
How bad is it · Garage, carefully
Fine to drive gently to a fix, but get it sorted soon
A missing brake light gives the car behind less warning, and a dead rear lamp is an MOT or inspection failure. Most of these faults come down to a fuse, so it is rarely a long job.
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.
Dim or dead on one side: a blown rear fuse
Each rear cluster takes a permanent 12 V feed through its own fuse, and the rear electronic module lights a lamp by switching its earth. With that fuse blown, a little voltage still creeps back through the other bulbs, so the lamps glow faintly and the fault looks like a bad earth or a failed module.
Tail and brake lights on one side are both dim, the tail light goes out when you press the brake, or the dash swaps between 'right brake light failure' and 'right tail light failure'. On the other circuit, an indicator is dead and the reverse lamp flashes in its place. It often starts straight after a bulb change or body work at the back.
Pull the fuses for that side and test them with a meter, not by eye. Then measure the supply wire at the cluster against the good side: for example, about 13.2 V on the healthy side and only 13 to 15 mV on the faulty one is a dead feed, not a dead earth.
A new fuse of the right rating. If the indicators and reverse lamps misbehave, change both F48 and F44: with only one replaced, the reverse lamp can still flash where the indicator should. Unplug the cluster connector before you pull a bulb holder, or the holder can touch the body and blow the fuse again.
One circuit dark with a good fuse: the rear electronic module
The rear module handles both the feed and the earth switching for the rear lamps. When the bulbs, fuse, wiring and plug all check out and earthing the lamp holder by hand lights it, the module's output for that circuit has gone.
One function on one side stays dark, for example the left tail lights with the headlamps on, while brake lights and indicators on that side work.
Swap bulbs side to side and confirm the fuse. Then unplug the module, make sure no pins have backed out of the connector, and refit it before you condemn it.
A replacement module with the same part number and revision letter. Check afterwards that the car still starts every time: a mismatched used module can cause a no-start of its own, cured by refitting the original.
Failure message while the lamp still lights: the bulb monitor
The car decides a lamp has failed by comparing the resistance of its circuit with a fixed value. Anything that shifts that resistance brings up the message even though the lamp still shines: one dead element of the two tail bulbs on a side, a corroded socket, or LED bulbs drawing too little current.
A 'rear brake light malfunction' or brake lamp failure message on braking, sometimes coming and going, while every lamp you can see is lit. Or the message arrived the day LED bulbs went in.
Look at both tail elements on that side, not only the bright one, and at the socket contacts for green corrosion. The high-mounted stop lamp is a row of LEDs, and a single dead LED there is worth suspecting too.
A new bulb or a cleaned socket clears it. With LED bulbs, worth trying a resistor in parallel so the circuit looks like a 5 W bulb, about 32 ohm; measure the LED first and expect it to look a little dimmer.
Dim on one side with the fuse intact: corroded earth, contacts or a wet boot
With the lamp off there is battery voltage on both of its contacts, and it lights when the module switches the earth. A corroded contact in the lamp unit or a dirty earth screw behind it dims the lamp without blowing anything. Near the right-hand rear lamp there is also an unused connector left from a transit relay taken out before delivery; in a flooded boot it can sit in water and short.
Lamps on one side dim with a good fuse, or the tail light on that side works but the brake light reports a failure. Water under the spare wheel makes it more likely. Brake lights lit all the time with the ignition on, with the ABS and brake warnings, are worth checking for the same reason.
Measure across the bulb contacts on both sides with the lamp off; for example, about 13 V on each contact is normal. Lift the boot floor, look at the terminal screws behind the lamp, check for standing water, and find any loose connector hanging near the right-hand lamp.
Worth trying: clean the contacts and earth screws, dry the boot and clear its drain, then tape up the unused connector and tuck it out of the water.
Indicator and reverse lamp dead with good fuses: a broken feed wire
On facelift cars the right-hand cluster plug, CA68, carries the indicator and reverse feed on pin 2 and stop, tail and fog on pin 6. No voltage on pin 2 with F48 intact means the wire is open somewhere upstream. Earlier cars use a different diagram and different pins.
The indicator and reverse lamp on one side flash dimly together and the other side's indicator joins in. Pulling the reverse bulb stops the flashing, but the indicator stays dead.
With the plug off, measure each pin against the diagram for your car, facelift or not. Where the 12 V goes missing, trace the wire back from there.
Bridging pin 2 to pin 6 brings the lamps back, but it ties two separate circuits together. The proper cure is to find and repair the open wire.
Rear side light stays on after you switch off
If pulling the fuse doesn't put the lamp out, it is being fed from somewhere else. A shorted diode between the side light and the rear module would do exactly that.
One rear side light stays lit with the engine off, often straight after a fuse in the boot was changed, and pulling that fuse again makes no difference.
Find from the fuse list for your year which fuse really feeds the side lights on that side, then test the diode between the lamp and the rear module.
No cure confirmed yet; the diode is the part to test 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.
Which lamps, which message
Note which lamps on which side are dim or dark, and the exact dash message. Tail and brake on one side share one fuse; indicator, reverse and side marker share another.
freeThe rear fuses
On 2007–2008 cars the luggage compartment fuse box has F53 for right-hand stop, tail and fog lights and the high-mounted stop light, F57 for the left-hand stop, tail and fog lights, F48 for right-hand reverse, indicator and side marker, and F44 for the left-hand ones, all 10 A. If no brake light works on either side, check F35, 5 A, in the passenger compartment box: it feeds the brake switch. Earlier cars differ, so check the fuse list for your year, and test fuses with a meter.
freeBulbs side to side
Swap the bulbs left to right and check both tail elements. Unplug the cluster connector first so a holder can't short to the body.
freeVoltage at the cluster
Compare the supply at the cluster with the good side. Millivolts where the good side shows about 13 V is a dead fuse feed, whatever the lamps look like.
free with a multimeterEarths, contacts and water
Lift the boot floor. Check the earth screws behind the lamp and the bulb contacts, look for water under the spare wheel, and tuck away any loose connector near the right-hand lamp.
freeLED bulbs and the high-mounted lamp
If the message came with LED bulbs, refit filament bulbs to confirm it, then add load resistors if you want to keep the LEDs. Check the high-mounted stop lamp for a dead LED.
a bulb or a resistorThe rear module last
Only when feed, earth and plug all check out. Match the part number and revision letter, and make sure the car starts reliably afterwards.
a used moduleThe 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 handbook, 2007 edition, p. 9, 10. 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 handbook, 2007 edition, p. 7, 8. 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 S-Type Headlights Not WorkingFront lamps, xenon levelling and the light stalk.
- S-Type (X200) fuse boxes and fuse listRear stop, tail, indicator and reverse fuses for 2007–2008.
- S-Type fuse boxes, 2000Early layout, where the rear lamp fuses are numbered differently; other years from the same page.
- Jaguar S-Type Water Leak, Water in BootWater in the boot itself: seal, seams, lamp gaskets and vents.
- 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.