Bulb failure warning

[Peter D]

If there is nothing attached to the tow connector there can not be a current inbalance to bring the light on, unless the wiring is wrong but you would have blown a fuse somewhere. The light out relay unit is a bunch of reed relays bi-filer wound all linked together so as long as the current in each side of the car for each light circuit is within about 15 % the read relay does not activate and turn the light on. DO the test I suggested and come back. Regards Peter

[Peter D]

You do not say what age and model of car this is but if you have 5/12w day running lights I suspect someone has put a 5/21W stop and tail light in there and that is causing the problem. Regards Peter

[paul4be]

Hi again,
Car is a 1984 240 GL (B21A).

The wiring for the tow bar has indeed been scotchlok'd into the wiring for the rear light clusters.

I'll try removing all of the bulbs front and rear and see what happens. As the light was illuminated when the car came to me, I can't say when the indicated "fault" occured. Could be the tow bar wiring, but that's been in place for quite some time and I can't beleive that someone would drive around for years with a bright orange warning light illuminated on the dash.

Thanks again.

[TOOLS]

Check the fuses at the bottom of the fuse box, nos. 15 and 16,for left and right parking lights/instrument and panel lighting. I had the same problem on my 1986 240 saloon, I tried everything as I thought to sort this problem, even changed bulbs for new ones on both sides front and rear but still the warning light would not go out !!. Then by chance while checking something else I took out the two fuses and replaced them and found this had cured the problem. the bulb failure light went out for the first time since I had had the car ! It works fine now, coming on if a bulb fails as it should. My car is also fitted with trailer sockets which are also scotch lock connected. However the bulb failure light comes ON if a trailer is connected but goes out when it is disconnected. It may just be you have the same fault ?

[Alec Dawe]

Originally Posted by Peter D

If there is nothing attached to the tow connector there can not be a current inbalance to bring the light on, unless the wiring is wrong but you would have blown a fuse somewhere. Regards Peter

Can I, without wanting to be rude, say that this can be incorrect sometimes.
I had a tow bar and trailer socket professionally fitted to one car, and had major problems with it, every time it rained, it would track to earth across the socket, not enough to blow a fuse, but enough to bring the bulb failure light up on a Saab, which I assume uses a variant on the same current balance theme.
Temporary cure was copious amounts of WD40
Permanant cure was to dump the socket, and fit a new, more expensive, better weather protected one.

[Peter D]

By any chance has the previuos owner fitted a high level brake light in the rear window. Is so then he will have wired it to one rear brake light thuis the inbalance but only when breaking. I assume he has checked the tow socket is not full of water. Regards Peter