Jaguar Bumpers – fitting parking sensors

Dear Jaguar lovers we all must avoid scratching our modern Jaguar bumpers by fitting parking sensors. Today, bumpers are not one of the most solid parts of car as old day’s vehicles. The old hypothesis of making chassis as strong as possible and then bolting a hefty bumper has now less in style of modern car manufacturing. Because studies showed that in case of accident (when car hit something), they often did more hurt the passengers than any other external source. Therefore, in the running age car manufacturers make the central cabin as strong as possible with the progressively weaker ‘crumble zones’ front and rear to absorb the shock, so in case of accident only car would damage not the persons along for the ride.

As a result today’s Jaguar bumpers are light weight, yet strong enough to absorb the trivial knocks and are attached to the body with mounts that are designed to shatter at a certain force. Although, the idea of modern auto engineers is robust - gives better styling to the modern designs, but the matching colour bumpers look bad if scratched even a little. 

As we all know that whenever technology and human thinking updates, it brings some more and more things with new innovations, thus the ‘parking sensors’ were invented to protect modern car bumpers from scratches or parking damages. But matching colour bumpers with lightweight material need extra care while fitting parking sensors in them. Today, I’ll share some useful tips with you, related with the parking sensors fitting issue.

Here we go:

•        Rear bumper is secured with bolts adjacent to each tailpipe and slip joints behind the rear wheels. Safely remove the rear bumper to fit the sensors. Pull the wheel-arch liner out from behind the bumper lip, and then use a swivel ratchet to remove the two vertical bolts. The threaded hole behind the removable cover is for the towing eye, normally stored in the toolkit.
•        The entire bumper assembly should then slide off. It isn’t heavy but, when refitting, always have help to align the returns to the slip joints.
•        Use plenty of masking tape to protect the paintwork and provide a surface to mark the holes on. Read all the instructions thoroughly and take care positioning the sensors as a mistake at this stage could be expensive.
•        Use a hole-saw with relatively fine and teeth central point drill to drill holes. A small file will be needed to open up a slot for the positioning lug. The sensors are directional so must be fitted in appropriate direction.
•        In order to protect your car colour while painting, most sensors come with barrier rings to cover the insulators. If you got parking sensors without barrier rings then do not paint them, but if you do, please ensure that all the traces of paint are removed. Push the sensors carefully until they engage positively in the outer cover. You must ensure that all sensors are fitted in correct order as they’re numbered. 

Positioning the sensors

The sensors used car directional with sharply defined arcs of operation. To work effectively though, the sensors need to be positioned according to strict rules, which can include:

•       Min/Max distance between sensors
•       Min/Max distance to ground
•       Vertical alignment
•       Horizontal alignment

The last two are particularly important as a curved bumper can easily throw a sensor far enough off vertical to each end, far enough around the corner to read adjacent cars as an obstacle. Most kits come with wedges to compensate for angled bumpers – use them carefully. Also be careful, while keeping within the manufacturer’s spacing, to position the sensors away from any internal reinforcement inside the bumper beam.

•        Bring all the leads together to form a common loom, clipping it to the bumper sub-frame where necessary. Then remove the boot trim and drill a hole in the rear body behind the bumper large enough to feed wires and plugs through. Paint the bare edge then prevent water ingress by using a grommet sealed in with black silicone. There will usually be more than enough length to feed the wires in without refitting the bumper.

Important:

Unlike the XJ and XK range, an S-Type has reversed wiring layout, where power is applied permanently to all the lights, which are then selectively earthed when needed. Obviously, this effectively throws a spanner in the works for sensing system that relies on the lamp feed for its power supply.  Luckily, the solution is simple; just connect the red (positive) wire to the 12-volt supply and the black (earth) wire to the earth signal wire, basically a simple reversing of the normal routine.

•        Both the XJ and XK use this type of bumper mount, though the actual dimensions differ from each other. Bolted to the body is relatively weak composite bracket with an aluminium adjustable platform through which the bumper is bolted. To prevent problems in the future, note the height of the platform then unscrew the inner section and coat with Copper Ease, or similar, before refitting.
•        Likewise, give both the mounting bolt and spacer a through coating, as steel and aluminium do not a happy couple make. Sit the bumper back in place, feeding the wires through as it goes, then, before fitting the bolts, make sure the body gap is even all the way round.
•        The control unit will have numbered plugs for each sensor lead plus a further one for the beeper/display unit. I strongly urge you to go for the basic beeper and hide it under the rear parcel shelf between the body and the cover panel.
•        Regardless of how car is wired, the reverse light circuit needs to be identified. This can be done easily by tracing the metal strip back from the reverse bulb to the plug, then refitting the bulb holder and checking the wire with a circuit tester or test light while the lights are illuminated.
•        If you got parking sensor unit which has two wires, the red (positive) is spliced into the reverse light feed while the black (earth) is spliced into the common earth wire. All the joints are soldered without cutting and then insulated with tape.
•        The XK8 has a convenient recess with the fuse box. Feed the wires up from below and mounted the control box using the adhesive Velcro pad supplied. With all the boot trim back in place the installation will be completely hidden.
•        If you think, you can’t do all this then please leave this job to a skilled professional.

Calibration

Some parking sensor kits (like marketed by Cobra) require calibration before use; there are four simple steps.

     (1) 

Park your car 50cm from a convenient wall.

     (2) 

With reverse selected, turn ignition on until unit sounds constant tone for approximately two minutes.

     (3) 

Turn the ignition off and cut the blue looped wire exiting the control box.

     (4) 

Insulate the cut wire ends. If a sensor has to be replaced this wire will need to be reconnected and the above procedure repeated.                                  

  GOOD LUCK!