Check your 1988-1994 XJ6 Soldered Joints to Prevent Electrical Failures
Virtually all XJ40 electrical failures are caused by joint failure that is a poorly soldered joint on a printed circuit which, with continual heating/expansion and cooling /contraction eventually separates-intermittently at first, but leading to permanent failure. Once located, bad connections can often be re-soldered, the tricky part is finding them in the first place. From 1989 improved quality control, together with change to analogue instruments improved things in this area considerably.
The most common problem areas seem to be the lighting relay units, misleadingly known as bulb fail modules, the circuit boards behind the instruments cluster and the over-voltage relay for the ABA, previously mentioned. Should the wipers fail without reason, look for blown inline fuse behind the glove box - it was put there at the last minute to protect the motor should the wiper arm freeze to the screen.
When fitting a tow bar, the proper interface unit must be used for the trailer/caravan plug, otherwise permanent and costly damage may happen. The square headlamps found on Sovereign and Daimler cars are both costly to replace and can be limited in output, but it is possible to fit the quad round headlight arrangement(utilizing standard five-inch lamps) from a standard XJ6, as long the twin output control units are also fitted. Being body color the surrounding trim may have be painted to match the car.
See our Jaguar Parts Store Catalog to order parts.