Headlamps not working
Discussion
Just embarking on a fun puzzle.
Side lights work. Main beam works. Low beam has stopped. So no useful lights for driving.
The offside light started not working intermittently a while back. The old trick of giving the lamp a slap turned it on. A couple of weeks ago neither lamp came on and slapping both got them working.
As of yesterday neither come on and no amount of 1970s discipline gets them working.
Connections seem fine. H4 bulbs look fine and have replicated the issue with other bulbs.
I've tried thinking about the wiring but if it were wiring would main beam also not work? It's a 72 Range Rover and it crossed my mind there may be a redundancy in the wiring but wondered if the symptoms of intermittent loss and needing a slap triggered any ideas? I used to have to do similar to a Daimler and a mini in the past.
Side lights work. Main beam works. Low beam has stopped. So no useful lights for driving.
The offside light started not working intermittently a while back. The old trick of giving the lamp a slap turned it on. A couple of weeks ago neither lamp came on and slapping both got them working.
As of yesterday neither come on and no amount of 1970s discipline gets them working.
Connections seem fine. H4 bulbs look fine and have replicated the issue with other bulbs.
I've tried thinking about the wiring but if it were wiring would main beam also not work? It's a 72 Range Rover and it crossed my mind there may be a redundancy in the wiring but wondered if the symptoms of intermittent loss and needing a slap triggered any ideas? I used to have to do similar to a Daimler and a mini in the past.
If you had to slap a light to make it work then the connections are probably not 'alright'. Infrequent use is likely to mean the earth or power connections are a bit iffy. For both main beams to fail then it is unlikely to be the H4s.
My 2cv does this now and then - but only on the right hand indicator! It is an earth problem. Dimple checks with a multimeter will help you to find out whether it is power or earth. Or corroded bullet connections etc.....
My 2cv does this now and then - but only on the right hand indicator! It is an earth problem. Dimple checks with a multimeter will help you to find out whether it is power or earth. Or corroded bullet connections etc.....
Not sure what the wiring is like in a 70s Range Rover but are there any bullet connectors between the main loom and H4 plugs?
I've had the dipped decide not work work/full beams still work and as a "get you home" was able to swap the bullet connectors so I had working dipped (with switches set to full beam)/no full beams. Of course the same swap can be used to help trouble shoot - if you swap and the working lights swap it's a fault between the bullet connector and the bulb. If it doesn't it's the other way between the bullet and the switch/battery.
I've had the dipped decide not work work/full beams still work and as a "get you home" was able to swap the bullet connectors so I had working dipped (with switches set to full beam)/no full beams. Of course the same swap can be used to help trouble shoot - if you swap and the working lights swap it's a fault between the bullet connector and the bulb. If it doesn't it's the other way between the bullet and the switch/battery.
All good advice, except possibly Aladdin's lamp.
Get a multimeter - less than £10.
Use it to check continuity across the bulb terminals - no continuity = blown filament = new bulb. Easy.
If that's good, then earth the 'meter and use the probe end to check for volts at the connector. With the lights turned on, Obviously. No volts = bad connection further up the loom, so move on up until you find Volts. Between no volts and volts is the fault.
Good luck!
John
Get a multimeter - less than £10.
Use it to check continuity across the bulb terminals - no continuity = blown filament = new bulb. Easy.
If that's good, then earth the 'meter and use the probe end to check for volts at the connector. With the lights turned on, Obviously. No volts = bad connection further up the loom, so move on up until you find Volts. Between no volts and volts is the fault.
Good luck!
John
Quick look in the old Haynes manual I've got (my factory manual is 1986 on) shows the mains & dips are separately wired. This also in my '86 manual.
Live feeds from the dip/main switch & depending on the year there is a join either before the fuses or on earlier models (the Haynes doesn't put the year. Helpful - not) somewhere after the fuses.
I do know that the combined dip/main column switch on my type (PRC4606 with white connector plug) are notorious for melting the contacts - which is why I altered mine so the switch just operates relays.
That they worked when you hit the units would suggest the issue is at or near them.
Trace the wires & clean all connectors & earths, using a multimeter to check.
I have a number of lengths of wire with small crocodile clips at each end - a hangover form my Scimitar owning days - and these can be very useful for finding faults. Connect one end to battery earth terminal & the other to the earth of the item being tested.
FWIW few years ago I had a non running fuel pump on mine & that turned out to be corrrosion inside the wiring just up from one of the joints.
Digital Mmeter said battery voltage throughout.
Found by using a pin on a piece of wire & a test bulb.
One side of bulb to earth & push the pin through the insulation until the bulb lit.
Corrosion in the wire was enough to allow a digital mm to show battery volts but not allow sufficient current to power the fuel pump.
Live feeds from the dip/main switch & depending on the year there is a join either before the fuses or on earlier models (the Haynes doesn't put the year. Helpful - not) somewhere after the fuses.
I do know that the combined dip/main column switch on my type (PRC4606 with white connector plug) are notorious for melting the contacts - which is why I altered mine so the switch just operates relays.
That they worked when you hit the units would suggest the issue is at or near them.
Trace the wires & clean all connectors & earths, using a multimeter to check.
I have a number of lengths of wire with small crocodile clips at each end - a hangover form my Scimitar owning days - and these can be very useful for finding faults. Connect one end to battery earth terminal & the other to the earth of the item being tested.
FWIW few years ago I had a non running fuel pump on mine & that turned out to be corrrosion inside the wiring just up from one of the joints.
Digital Mmeter said battery voltage throughout.
Found by using a pin on a piece of wire & a test bulb.
One side of bulb to earth & push the pin through the insulation until the bulb lit.
Corrosion in the wire was enough to allow a digital mm to show battery volts but not allow sufficient current to power the fuel pump.
Edited by paintman on Wednesday 14th December 11:46
Usually, bulbs working after a slap denotes a dead bulb. The other favourite for this is poor earths, dirty contacts in the dip switch or a duff relay. I'd do the easy stuff first - check any fuses, clean earths, replace bulbs, replace relay, clean dip switch contacts. Always start with fuses first though 
Thanks everyone. It's been the aspect that slapping the lamps made it an intermittent fault that has confused me.
Going to attack the lamps with a multimeter later and see what I find.
The lamps should be on a relay from the switch as those switches burn out and I fitted some spots earlier in the year and I'm sure a relay was added at the time.
Going to attack the lamps with a multimeter later and see what I find.
The lamps should be on a relay from the switch as those switches burn out and I fitted some spots earlier in the year and I'm sure a relay was added at the time.
My Defender, which is (slightly!) newer than your Classic, pulls stunts like this every so often. Usually it's the day before the MOT is due.
I expect there's a lot of shared DNA. Most of the lighting wiring is connected with bullet connectors on mine, and much of that looks standard rather than a subsequent bodge by someone. They're generally encased in s soft-ish rubber sleeve, which is anything but waterproof. Wiggling them often brings the light in question back on, so if you pull the offending connector apart and clean it, that will often cure it. It is actually often the earth connector at fault, which correlates with comments above.
I expect there's a lot of shared DNA. Most of the lighting wiring is connected with bullet connectors on mine, and much of that looks standard rather than a subsequent bodge by someone. They're generally encased in s soft-ish rubber sleeve, which is anything but waterproof. Wiggling them often brings the light in question back on, so if you pull the offending connector apart and clean it, that will often cure it. It is actually often the earth connector at fault, which correlates with comments above.
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