960/90 headlight relays?

[Jim760]

Originally Posted by Mike Arnold

The fact that the bulbs are blowing so quickly (immediately?) does not seem to be a relay thing. Either the bulb is overheating (which would take between several minutes to hours to blow) or else the voltage is too high. The latter can be caused by the alternator regulator going bonkers.

Headlight bulbs are more vulnerable to over-voltage than sidelight bulbs. The voltage across the bulb should be no more than 14.5V (but more likely to be 13V) with the engine running.

Maplin sell multimeters for under a fiver and they are well worth buying.

hi
yes they pop instantly, dont even try to light. i tryed this with out the engine running so it cant be over voltage can it? the only 2 possable probs being, is that i hve replaced the dash board maybe caught a wire or something? and not checked the headlamp relays atall.. i had the light switch apart for cleaning, and i thought it may have been that which was causing the probs, but trying another switch has proven that to not be the case. i will gobuy a multimeter asap.

Pleas note!! the car in question is a 760 GLE, wich was designed to run H4 headlights (dual filaments) and now with H1 single filaments as per the 960 i got the parts from!
cheers

[CTCNetwork]

Hi,

The H4 bulb has two supplies for the different filaments, dipped and main beam and a common earth....

The 960/90 has for this two different bulbs each with a single supply and a single earth...

Maybe you have crossed your supplies and given two +ve supplies to the bulb and therefore are blowing the bulb before the fuse??

Des. . .

[niloc]

Originally Posted by CTCNetwork

Maybe you have crossed your supplies and given two +ve supplies to the bulb and therefore are blowing the bulb before the fuse??

Can't be 2 +ve supplies - only 1 battery.

[CTCNetwork]

Hi,

Originally Posted by niloc

Can't be 2 +ve supplies - only 1 battery.

You can have two +ve feeds instead of the normal +ve and -ve..

Des. . .

[niloc]

Voltage = potential difference.
+12v on one side and 0v (-ve) on the other side = a 12v potential.
+48v one side, and +36v the other = 12v potential, so a 12v bulb could be used.
+12v and +12v = no potential, therefore no light.
You need to understand the principle of electronics!
As there is only 1 battery (power supply), and no transformers in the headlight supply, there can never be more than battery voltage at each bulb.
The fact the bulbs are blowing is either severe arcing on the circuit, or the bulbs are not rated at 12v.

[Jim760]

Originally Posted by niloc

Voltage = potential difference.
+12v on one side and 0v (-ve) on the other side = a 12v potential.
+48v one side, and +36v the other = 12v potential, so a 12v bulb could be used.
+12v and +12v = no potential, therefore no light.
You need to understand the principle of electronics!

err.... yeah i sort of follow that

Originally Posted by niloc

As there is only 1 battery (power supply), and no transformers in the headlight supply, there can never be more than battery voltage at each bulb.
The fact the bulbs are blowing is either severe arcing on the circuit, or the bulbs are not rated at 12v.

now i FULLY understand that... wellwe know H1's ARE 12v.. so it looks to be a short then? wonderfull. i bet ive damaged something when removing and fitting the new dash!

[Jim760]

well well...

spent today going through every wire in the lighting system, tested every other light on the car. i seen some mad flashing light combos i can tell you! like,locking the brake light on preduced 7, yes 7! rear lights to glow..those being the 4 running lights both fogs and the 3rd level brakelight! left indicator produced a flashing running light rathert han indicator,and a faint glow in the reversing light in the LH side.. and on the right we had a foglight onA ND a front sidelight!!! thats only part of what i seen.

so after going though everything (have been at this all day) is:

rear LH light cluster earth point and the solder on the board its self.

water ingress has made flood in RH rearlight

number plate bulb shorting to bodywork

wires for AC fan + and - sorting to body

common earth for RH front headlight corroded and loose

and the biggest cuprit: headlight relay malfunctioning!

relay fixed itself when i had sorted the above faults. also the indicator relay was playing up in the same way, was making a continuesus "nreeee" sort of noise when trying to oporate.. just like the headlight relays where!
so thats it all working! every lastlight as it should be and no more poping ofbulbs!! mind you, the sidelight had the last laugh... poped on meafter putting everything back together!!!!
thanks to all who gave help in trying to sort this problem, just shows that a good bit of digging about can find underlying probs!

[cumbrianmale]

Well done

[CTCNetwork]

Hi,

Glad you got that sorted...

Hate to have an electrical problem on any of my cars...
Probably weld myself to something..!!

Des. . .

[s60ben]

Originally Posted by CTCNetwork

Hi,

Glad you got that sorted...

Hate to have an electrical problem on any of my cars...
Probably weld myself to something..!!

Des. . .

Given your knowledge of electrical theory, you'd be lucky to strike an arc.

And just think, not one person got the correct answer.

You all failed the Faraday Law exams

Shame I only just spotted this


PS. I've never seen so much b*****ks written about electrical systems in my life as in this thread. And yes, before anyone asks, I do have qualifications in Electical, Electronic & Instrumentations