Jaguar XJ6 (X300) ABS Light On, ABS Pump
On the X300 the moment the ABS lamp comes on tells you most of the story. On from start-up usually means a wheel sensor or its wiring; out at start and back at about 12 mph usually means the module under the pump, most often cracked solder on the motor pins (code C1095). I'd charge the battery and clean the plugs before spending anything, and if traction control cuts the power with no lamp at all, look at the tyres first.
How bad is it · Garage, carefully
The brakes still work, just without ABS or traction control
When the lamp is on the system falls back to ordinary brakes. Leave more room in the wet, and in the UK the lamp is an MOT failure.
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.
Cracked solder on the ABS module's motor pins
The control module is the black plastic box bolted under the ABS pump. The joints that carry power to the pump motor crack with heat and vibration, often without looking broken, and the module fails its own test.
Lamp out at start-up, then on at about 12 to 15 mph and on until the next restart. Often temperature-sensitive and intermittent for months before it stays on. The ABS code is C1095, pump motor circuit. The same pattern can appear straight after hub work and still be the module.
Read the ABS codes. Measure the four sensors at the module plug first; if they are all in range and the code is C1095, the module is the suspect. The pump motor itself reads about 0.8 ohm at its plug. Even with C1095, clean the four hub sensors and look at the earths first: they cost nothing.
Send the module to a rebuilder, or open the case along the seam, scrape the clear coating off the motor terminals and re-solder them even if they look fine, then seal it again. The module can usually be unbolted from under the hydraulic block without opening a brake line. A used module has to match: there is one type for cars with traction control and one without.
Dirty plugs on the ABS module and pump
The unit sits low in the engine bay by the bulkhead and its plugs collect damp. A corroded or half-seated pin is enough to fail the test and bring on ABS and TRAC FAIL together.
Lamps come and go, sometimes clearing with a restart, sometimes after rain or after work nearby. Blackened pins in the large connector. Lamps can also clear for good once the big module plug has been cleaned and greased.
Undo the bolt that draws in the big multi-pin connector on the side of the unit, pull the small two-pin plug to the pump motor and, if fitted, the traction control actuator plug. Look for green or black pins.
Clean every pin with contact cleaner, add a little dielectric grease and refit the big connector by its bolt. If the lamp returns after a few months, the joints inside the module are next.
A wheel-speed sensor or its wiring
Each wheel has a passive magnetic sensor reading a toothed ring on the hub. A sensor coated in grime, a corroded plug or a chafed harness drops the signal and the module lights the lamp. The sensor is rarely dead; the wiring usually is.
Lamp on from start-up and staying on. If the speedometer also stops or wanders, look at the right rear sensor first: it feeds road speed to the instruments, cruise and gearbox.
At the 28-pin module plug, pins 5/6 are left front, 7/8 right front, 9/10 left rear and 11/12 right rear. Each pair should read about 1.1 kohm, within 50 percent, and hold steady when you wiggle the harness. Open circuit means a broken wire or sensor. With the plug off, put a voltmeter across one pair and spin that wheel: a small voltage, around 1 V, should appear. A sensor lead parted inside its grommet gives an on-off contact that only shows when the harness moves.
Pull, clean and refit the sensors, clean the toothed rings and the plugs (fronts in the engine bay at the wheel arches, rears under the rear seat). Repair a cut or chafed wire before buying a sensor. Hosing the grime out from behind the wheels has cleared a lamp for good. Clean the sensor faces and the toothed rings at every pad change, and refit with copper grease: water rots the aluminium round a dry sensor and it seizes.
Traction control misreading odd tyres
Traction control compares the wheel-speed sensors. A rear wheel turning faster than a front one looks like wheelspin, so a smaller spare, a soft tyre or worn rears against new fronts make the actuator close the throttle.
No warning lamp. The car won't pass about 30 mph or 50 km/h, or the pedal pushes back and pulses at speed like cruise control. It drives normally with TRAC OFF, and it started after a tyre change, a puncture or a wheel swap.
Press TRAC OFF and drive: if it pulls normally, the engine is fine. Compare the size on all four tyres and look for a spare on one corner. Check the pressures: one soft tyre is enough.
Fit four tyres of the same size and set the pressures; renew worn rears in a pair. If it still cuts in over potholes and broken corners, tired dampers are worth a look next.
The throttle cable through the traction actuator
The pedal cable runs into the actuator drum and a second cable runs on to the throttle. The two halves of the drum are joined by a spring clutch, so a stiff cable, a binding throttle or a broken cable fitting lets them slip and the throttle stops short.
Flat performance with the pedal on the floor, the throttle hanging open between gears, or the engine dropping to idle with no response at all. Switching TRAC OFF makes no difference.
With the engine off and then running, have someone press the pedal while you watch both cables: their travel should match. Read throttle opening with a scan tool at full pedal; for example, one car opened only 33 percent and another 51. Work the throttle by hand when cold: if it binds, the actuator cannot overcome it.
Lubricate a stiff cable, set both cable adjusters between slack and tight, and repair or replace a cracked fitting where the cable leaves the actuator. If the throttle body itself is sticking, clean and free it before blaming the actuator.
A tired or flat battery
The ABS module is very sensitive to supply voltage. With a weak battery the pump can't build pressure quickly enough and the after-start check fails.
ABS and TRAC FAIL lamps, or TRAC FAIL alone, after the car has stood for weeks, in cold weather, or on a short trip straight after starting. A restart on a charged battery shows no warning. The lamps can come on with the battery only slightly below full.
Charge overnight and load-test the battery. Watch whether the lamps return once the voltage is healthy.
Worth trying first: charge or renew the battery and let the engine run a minute before driving off. If the lamp then stays out for a week of driving, nothing else needs doing.
The traction actuator's plug and wiring
On cars with traction control a motor unit sits in the throttle cable, on the left of the engine bay behind the coolant tank. Its plug and wires live in engine heat; the insulation cracks and the plug corrodes or crumbles, and the module lights TRAC FAIL, usually with ABS.
TRAC FAIL, often with the ABS and TRAC OFF lamps, that comes and goes. Touching or moving the wires at the actuator changes it.
Take off the plastic cover over the actuator and look at its plug and the first few inches of wire for bare copper or a cracked shell. The throttle position sensor plug is worth a look too: unplugged, it also brings on the TRAC and TRAC OFF lamps. Pulling the actuator plug brings on the same lamps, so a poor contact there will too.
Worth trying: clean and re-seat the plug and sleeve any bare wire in heat-shrink. If the plug has gone to dust, a used actuator from a breaker, bought with its plug and a few inches of wire, is far cheaper than new (actuator MNA5930AA, cable to the engine MNA4620JC).
Old or contaminated brake fluid in the ABS valves
The valves in the hydraulic block have tiny orifices. Debris from a careless fluid change, or old fluid pushed back when the caliper pistons are retracted, can make a valve hang.
ABS acting on its own near the end of a stop, or a sporadic lamp, starting soon after a brake service.
Look at the fluid colour and ask what was done at the last brake job.
Worth trying: a careful full flush and bleed. When pads are changed, open the bleeders before pushing the pistons back so the old fluid goes out rather than into the ABS block.
A worn wheel bearing or a loose sensor
The sensor needs a steady gap to its toothed ring. Play in a hub bearing, a ring slipping on the hub or a sensor bolt that has worked loose makes the signal jump and the module thinks a wheel is locking.
The pump buzzing or the ABS pulsing on turns or at low speed with no reason, sometimes with a growl from that corner and cruise dropping out.
Jack the car and rock each wheel for bearing play. Check each sensor bolt is tight and the sensor isn't rubbing.
Worth trying: renew a worn bearing together with a damaged ring, or replace a missing sensor bolt. Regreasing tired bearings is worth a try before replacing them, unless they are already shot.
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.
Charge and test the battery
Charge it overnight and load-test it. Low voltage alone brings on ABS and TRAC FAIL, so rule it out before anything else.
freeWatch when the lamp comes on
It should light with the ignition and go out. If it never lights at all, the bulb in the instrument pack has gone. On from start-up points to a sensor or wiring; out at start and on at about 12 mph points to the module.
freeIf only traction control misbehaves, press TRAC OFF
If the car drives normally with TRAC OFF, look at tyre sizes and pressures first. It switches back on at every start and can't be latched off. No TRAC button on the console means the car has no traction control, even though the lamp lights in the bulb check.
freeRead the ABS codes
An engine code reader won't see the ABS module. You need Jaguar's own diagnostic tool or a scanner that reads Ford ABS; it names the silent sensor or gives C1095 for the pump motor circuit.
cheap at an independentClean the module and pump plugs
The big connector on the side of the unit is drawn in by a bolt; the motor plug and any traction actuator plug pull off. Contact cleaner, a little dielectric grease, refit.
freeCheck the traction actuator
On cars with traction control, look at the actuator plug and wires on the left behind the coolant tank, then watch both throttle cables move together while someone presses the pedal.
freeMeasure the sensors at the module plug
Pairs 5/6, 7/8, 9/10 and 11/12 on the 28-pin plug, about 1.1 kohm each. Wiggle the harness while you read; a jumping or open reading finds the bad corner.
freePull and clean the sensors
Each is held by one bolt. Soak with penetrating oil for a day, then twist gently and never lever: rear sensors seize in the aluminium hub and break. Coat them with anti-seize before refitting.
freeRebuild the module
If the sensors and plugs are good and the lamp comes on at speed, have the module rebuilt or re-solder the motor pins yourself. A dealer's new pump assembly costs many times more and is rarely needed.
about 50 to 200 dollars by postWhat it usually isn't
Don't spend money here first:
If none of this finds it:
On jagaux.com
- Jaguar XJ6 (X300) Instrument Cluster, Dash LightsIf the speedometer has died along with the ABS lamp, or every warning lamp is flickering.
- Jaguar XJ6 (X300) Alternator Not ChargingIf the ABS and TRAC lamps keep coming back with a battery that won't stay charged.
- Jaguar XJ6 (X300) Battery Drain, Flat BatteryIf the lamps appear after the car has stood and the battery is low.
- XJ6 (X300) fuse boxes and relays1996 and 1997 from the same page.
- Jaguar XJ6 (X300) Wheel Bearing NoiseIf a worn or loose wheel bearing is the suspect behind the ABS lamp.
- 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.