Sporadic headlights...!!!

G

grifterkid

Member
I'm sure this is a simple connection problem but the other evening when driving along with the headlights on they suddenly died...! When I switched to full-beam all 4 lights operated perfectly and then when I went back to normal operation (non full-beam) the headlights came on and went way intermitenttly...! They all work 100% on full-beam but not on normal beam so do any of you fine people have any suggestions for me...? The sidelights operate normally too... Any help would be hugely appreciated...
 
if you have the fuse box in the glove compartment check the contacts are clean. I have had these melt in the past. Also look out for cheap fuses.

Colin
 
You could have a bad contact on the dipswitch which is heating up then cutting the power. Possible to clean with a bit of fine wet and dry paper
 
DaveHerns said:
You could have a bad contact on the dipswitch which is heating up then cutting the power. Possible to clean with a bit of fine wet and dry paper
Click to expand...
As a mechanical simpleton (!) where would I find the area I need to clean up...?
 
grifterkid said:
I'm sure this is a simple connection problem but the other evening when driving along with the headlights on they suddenly died...! When I switched to full-beam all 4 lights operated perfectly and then when I went back to normal operation (non full-beam) the headlights came on and went way intermitenttly...! They all work 100% on full-beam but not on normal beam so do any of you fine people have any suggestions for me...? The sidelights operate normally too... Any help would be hugely appreciated...
Click to expand...

Sounds like a fusebox problem to me - if you have a post October 1971 car they're prone to melting down with age....even on low mileage cars...
 
I had the opposite problem until recently. I was driving along with the lights on full beam when all of a sudden it went dark :eek: I switched back to dip and the lights came on (phew!)

The main beam flash worked but the permanent main beam didn't. I removed the switch and gave it a good clean but the permanent main beam refused to work. I'd been keeping an eye out on eBay for a replacement for ages with no joy. There are loads of indicator switches but never any dip/main beam switches. Anyway, the main beam started working again all by itself over the weekend (well I had to move the switch but it worked this time) so I've no idea what caused it not to. Dodgy switch probably. Guess what turned up on eBay the same day??????? You guessed it....... a dip/main beam switch. I've snapped it up as a spare.

Doesn't help your problem I know but it's a good story :)

Good luck with your switch/fuse/bad earth (have you thought of that one?)

The switch is a bugger to get out without taking the steering wheel off by the way.

Dave
 
NickDunning said:
grifterkid said:
I'm sure this is a simple connection problem but the other evening when driving along with the headlights on they suddenly died...! When I switched to full-beam all 4 lights operated perfectly and then when I went back to normal operation (non full-beam) the headlights came on and went way intermitenttly...! They all work 100% on full-beam but not on normal beam so do any of you fine people have any suggestions for me...? The sidelights operate normally too... Any help would be hugely appreciated...
Click to expand...

Sounds like a fusebox problem to me - if you have a post October 1971 car they're prone to melting down with age....even on low mileage cars...
Click to expand...

Is a new fusebox the solution to this (obviously I'll test all the theories)...?! I know it sounds silly but do they melt in an obvious way i.e turning into a plasticy blob...?
 
I have had in the past had the headlamp relay go faulty which produced intermittant lighting problems which when you flicked the dash knob cured the darkness for a time.

Graeme
 
grifterkid said:
NickDunning said:
grifterkid said:
I'm sure this is a simple connection problem but the other evening when driving along with the headlights on they suddenly died...! When I switched to full-beam all 4 lights operated perfectly and then when I went back to normal operation (non full-beam) the headlights came on and went way intermitenttly...! They all work 100% on full-beam but not on normal beam so do any of you fine people have any suggestions for me...? The sidelights operate normally too... Any help would be hugely appreciated...
Click to expand...

Sounds like a fusebox problem to me - if you have a post October 1971 car they're prone to melting down with age....even on low mileage cars...
Click to expand...

Is a new fusebox the solution to this (obviously I'll test all the theories)...?! I know it sounds silly but do they melt in an obvious way i.e turning into a plasticy blob...?
Click to expand...

Fairly obvious yes

melted.jpg


The reasons they melt are many and varied but all make the fuse box very hot.

1/. The plastic bits beside the spades act as springs to keep the fuse tight. They get weak with age and the fuse becomes loose, which can create heat when current flows. The heat weakens the plastic more, weakening the springyness and creating more heat. Vicious circle, fuse box melts.

2/. The spades can become dirty with age creating the heat when current is bridging the scale.

3/. Smaller fuses can be used as the proper size ones are difficult to obtain. Less area for current to flow, creates the heat.

4/. More electrical or upgraded items may have been fitted which uses more current, creating the heat. Upgraded headlights for instance, or kenlowe fan wired into the wrong circuit without a relay.

So get some emery cloth and clean up the ends of the fuses, clean up the spades which hold them in the fuse box, and check there is nothing wired into the headlight circuit which could overload it. Check the fuses are 31mm long, and check the headlights have not been upgraded.
 
Expected splendid answer from Nick! Just to emphasisethat the item 3 defect - small fuses - relates to fuses that are too short - as in the picture.

Melting fuse box is a standard defect with the P6. Worse, it is established that melting fuse box is alrmingly easy to transform into burning fuse box. Curiously the same fuse box is used without apparent issue in the P5. The only obvious thing that could explain this is that different sub contractors making up the respective wiring looms had different success rates in crimping up the terminations onto the fuse box. A further recommendation is therefore to take the time and trouble (its not in a very accessible location!) to crimp up your connections as tight as you can.

Or of course change for a modern fuse box!

Chris
 
Forgot to mention that the bullet connectors in the headlamp wiring can get scaled up. This will mean more current is needed and can heat up the fuse box.

Richard
 
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