XJ40 Bulb Failure Modules (Again!!)

Like most owners of early XJ40's I suffered with the Bulb Failure Module problems and that accursed huge flashing warning light.

Again like most XZJ40 owners I searched the newsgroups and avidly read up on the issue on

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only to find a heap of info, some good and some not so helpful. These BFM's really can be a pain and isolating which one (or more than one) that has failed is troublesome to say the least.

On my travels I did learn something that may be of use to others and which I had not come across elsewhere.

My XJ40 is a UK 1987 3.6 Sovereign with the large rectangular headlights although this might be appropriate for other varients of the XJ40.

As all of us who have experienced this problem know, there are 4 BFM's, two at the rear in the boot (one each side in the wings just forward of the light clusters) and two at the front (one each side of the radiator just backward of the headlights). It seems that is more often than not one or both of the front BFM's that fail, partly I guess due to their relatively exposed location and also because they are more complex than the rear modules, the fronts having two circuit boards one piggy-backing on the other.

Assuming you have already removed and cleaned all bulb connections (including the side repeater bulbs) BEFORE you go removing the front BFM(s) to attempt a resolder job have someone turn the lights onto position 1 (i.e. side - parking - lights only). The Sovereign with the rectangular lights were designed to illuminate the small side lights in the front bumper and also have the main 60/55 headlamp bulb run in a dimmed mode at the same time.

When the light switch is turned to side (parking) lights both the headlights will flash momentarily as if being turned on and then immediately operate as dimmed lights. If either tof the headlights do not light up in dimmed mode then you can be fairly sure that it is that respective front BFM that has failed.

If I knew this when I started out I would have saved myself countless hours replacing bulbs, soldering etc.

Bye the way Dave Manners in Wolverhampton (UK) sells reconditioned front BFM's for about £145 a shot.

Hope the info may be of use to someone else.

Andy

Reply to
Bruce
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Somebody needs to design a clear plastic applique with the bulb warning imprinted on it. Then you could paste it on the warning screen and it would blot out that irksome, impossible to cure, bulb warning message!!!!!!!!!!!! Trouble with modern cars is that the warning systems fail far more often than the actual devices they monitor. Maybe somebody could design a cheap replacement for the BFM's that always sends a signal that all's well.

I finally have my problem down to the point that I only need to erase the bulb failure message once, after I first start the car. Been living with it for 8 years and just got tired of throwing money at the problem. I've done everything I can think of, including swapping BFM's side to side, re-soldering the cards, removing/replacing all the bulbs, cleaning all the sockets, paying a shop to look at the issue several times, and replacing 3 modules (1 front, 2 rear).

Arrggghhh!!!!

End of rant.

Never heard of the dimmed headlight mode, and doubt my American

89 XJ40 n> Like most owners of early XJ40's I suffered with the Bulb Failure Module
Reply to
WayneC

Bruce, A couple of things. First off -- the US versions of the BFM are totally different than the UK versions. There is a different lighting sequence -- especially in the rear. The rear US BFMs have the second "piggyback" board as well.

As for complaints with these boards. They are painstaking to deal with BUT that being said, I have my '88 and 4 other friend's '88/'89s and NONE of them have the BFM warnings anymore. Most were a simple process of CAREFULLY resoldering the boards and the warnings went away. In two cases, we simply snipped the pink/slate sensor wire and the warning went away. Just make sure everything is working properly.

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