whats going on with my lights?

['88740GL]

Hi all,

I have a 1988 volvo 740, and the 'blown bulb' dash light is constantly on...all of the bulbs work fine, i've narrowed it down to the daytime running lights, on the driver side at the front, the bulb is lit, but only very dimly, the otherside however is great, I've even swapped the bulbs round and changed them for the correct new ones, still the same problem with the one side, i've tried cleaning the contacts, wd-40 incase water was getting in, i even found an earthing point from the bulb wiring and took that off, cleaned it, wiggled it and its still the same...

any ideas?


Thank you in advance!

['88740GL]

Originally Posted by '88740GL

Hi all,

I have a 1988 volvo 740, and the 'blown bulb' dash light is constantly on...all of the bulbs work fine, i've narrowed it down to the daytime running lights, on the driver side at the front, the bulb is lit, but only very dimly, the otherside however is great, I've even swapped the bulbs round and changed them for the correct new ones, still the same problem with the one side, i've tried cleaning the contacts, wd-40 incase water was getting in, i even found an earthing point from the bulb wiring and took that off, cleaned it, wiggled it and its still the same...

any ideas?


Thank you in advance!

Another weird thing is when i fiddled with the radio, (removed the horrid ford botch job, replaced it with the original one) the blown bulb light went out only to come on each time i pressed the brake pedal.......i then fiddled with the radio once again to fit the proper fascia on and now this blown bulb dash light stays on all the time again....damn electrical gremlins!

[Chris740R]

If it made a difference when you pushed the brake pedal, you could always go round the back and try cleaning the contacts there too. Especially the rear light/brake light bulb on each side. My bulb out light does this every now and then, it just required the contacts to be cleaned.

['88740GL]

Originally Posted by Chris740R

If it made a difference when you pushed the brake pedal, you could always go round the back and try cleaning the contacts there too. Especially the rear light/brake light bulb on each side. My bulb out light does this every now and then, it just required the contacts to be cleaned.

Cheers, i'll do that and get back to you :-)

[mikealder]

Make sure the bulb holders are 100% intact for the front day running lights as they tend to crack over time from the heat and don't hold the bulb correctly leading to all sorts of strange faults on the lighting circuit (I had this happen on my last two 740's) - Mike

[Jim760]

sounds like a short maybe? are you sure the bulb holder is the correct type for the dual filament bulb? its not uncomon for people to have changed them and not used the proper one. do the spades in the base of the holder look ok? not bent or anything? check if when you press them in, is one moving and trying to toch the other? (assuming yours is the clasic 740 front with dual filament bulb) if it is, can you confirm if its the 21w filament thats actualy glowing, but dim, or is it the 5w thats glowing?

as chris said the fault can flip roudn the car, check the ground leads coming from your tail lights.. them wee bugers can cause allsorts of weird reactions!

['88740GL]

Originally Posted by mikealder

Make sure the bulb holders are 100% intact for the front day running lights as they tend to crack over time from the heat and don't hold the bulb correctly leading to all sorts of strange faults on the lighting circuit (I had this happen on my last two 740's) - Mike

Hi, thanks for reply, the bulb holder do appear well intact, (the car has hardly been used through its life, only has 43,000 orig. miles on it, one of them do look a little burned with use though, and this is the one thats dim, maybe i'll give the bulb a little wiggle and see if its the connection there. I'll try tonight!

['88740GL]

Originally Posted by Jim760

sounds like a short maybe? are you sure the bulb holder is the correct type for the dual filament bulb? its not uncomon for people to have changed them and not used the proper one. do the spades in the base of the holder look ok? not bent or anything? check if when you press them in, is one moving and trying to toch the other? (assuming yours is the clasic 740 front with dual filament bulb) if it is, can you confirm if its the 21w filament thats actualy glowing, but dim, or is it the 5w thats glowing?

as chris said the fault can flip roudn the car, check the ground leads coming from your tail lights.. them wee bugers can cause allsorts of weird reactions!

in both front lamp holders are dual filament bulbs, so and the other side works fine, so i'm assuming that the holders are right, sine the pins on the side of the cap only enable the bulbs to fit in one way round, the connectors look a little grey, they seem to be tight in there and secure, though i can confirm that the spades aren't touching eachother as they still have their springness in them and a well away from one another (3-5mm), I'll check back to you tonight as to which filament is lighting up, and i'll file the earthing points to get them back to shiny metal and see if that helps if not.

thank you for your suggestions