low beam headlights kaput

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jvrenaudon

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The low beam headlights suddenly went dead last night, or, rather, they failed to come on when I started the car and switched them on. It's a Series 2 CSi December 1973 build car VIN 4350022 which means that, for a right-hand-drive car, the combined high/low beam and indicator switch is the left-hand stalk. I cannot locate a corresponding relay serving this circuit. All fuses are intact and test out. Bulbs work. I wondered if any one has any ideas? Everything else works fine. Thanks in advance. John.
 
jvrenaudon said:
The low beam headlights suddenly went dead last night, or, rather, they failed to come on when I started the car and switched them on. It's a Series 2 CSi December 1973 build car VIN 4350022 which means that, for a right-hand-drive car, the combined high/low beam and indicator switch is the left-hand stalk. I cannot locate a corresponding relay serving this circuit. All fuses are intact and test out. Bulbs work. I wondered if any one has any ideas? Everything else works fine. Thanks in advance. John.
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Check the wiring harness behind the bulb assembly. Mine came loose and wouldn't turn on, I had to remove the grill and some screws holding the light bulb. The wiring harness slides in and off a little metal connectors thats behind the bulb. Check to make sure it hasn't slid off or loose.

Sent from my SM-N910P using Tapatalk
 
On my car there is no relay serving this circuit. I am planning to add one to diminish the current flow through my light switch, in the hopes of extending the life of the switch.

You can check the wiring harness by removing the metal plate under the hood above the headlight assemblies, which if you are lucky is held in by three white plastic knobs (I say this because often these knobs get broken or are lost). After checking the wiring harness behind the light, follow the brown ground wire to the chassis ground and check the ground. Even if it is ok, clean up the wires, the screw and the contact point on the chassis. I use phosphoric acid to clean electrical contacts and the screws.

If those steps don't solve your problem, the next thing to check is the switch.
 
If both low beams are dark, then I wouldn't bother checking the wiring behind the bulbs. Yea, that wiring can come loose, corrode, etc. but the odds that both sides have failed simultaneously are pretty low.

I would concentrate on components that serve both bulbs: scanning my wiring diagram, the high beam / low beam switch seems like the most probable culprit.
 
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Thank you. I have sorted it. There IS a low-beam relay fitted to this RHD car. It is located just above the bonnet/hood pull handle to the left of the fuse box , looking forward. This relay had packed in. This relay is not shown on any wiring diagram I have in my possession but I can assure you that it is there. The relay could not be replaced by any relay I had in my spares box. Taking such a relay out of my spares, when I fitted it to the holder with everything turned off in the car, I heard (and felt) a distinct click from within the relay but, hey presto, the headlights worked. However, the relay warmed up. I took this four-point relay down to my local auto electrical shop and explained what had happened and he sold me a RLPA/4-12 NAGERES. This works fine; no click when I fit it and no warming up when the lights are switched on. Before I close this thread; two things. First, thanks for the ready help. Second, going through my spares box I came across no fewer than four headlight switches- two large pin and two small pin. I tried the two small pin and they tested out ok. One of these is available if anyone is stuck. Same goes for the large pin but, again, I need to save one as a spare for my RHD CSL which I know is fitted with this type. Best wishes, John.
 
That's interesting - LHD cars did not have a relay in the low beam circuit (at least not the pre-'74 models).

I wonder if RHD cars came with a low beam relay, or if a previous owner fitted one to your car. Its location (just above the bonnet/hood handle) seems odd; I would think the factory would have put it next to the high beam relay.

Glad you got it solved!
 
Since it was built Dec 73 it probably has all of the features of the 74 coupes which do have the low beam relay which earlier cars did not.
 
Simon, Yes, I will try but you're welcome to inspect for yourself if you're passing. Chris, I think you are correct. The installation bears all the hallmarks of OE, in my opinion. The relay holders are typical of others elsewhere on the car and the integration of the relay into the wider loom shows no sign of being a "lash-up" or post-build modification The car itself is itself considered a 1974, being one of the first of the Series 2 CSi's, I believe. However, the instruction manual which appears to have come with the car gives a wiring diagram which does not correspond with the as-built features of the car in this and other respects.

My December 1972 built- and shipped- Citypack CSL VIN 2285295 is different again . Here, though, the original set-up no longer exists because shortly after I bought the car I had the twin-headlamp dip- and main-beam conversion done. This does involve the fitment of a low-beam relay in order to cope with the increased wattage of four bulbs in each mode involved. Consequently, the original build is not present for comparison.

Happy to say that I went for a spin in the CSi tonight and can report everything ship-shape and Bristol fashion.

Thanks again for the assistance,
J.
 
In fact, the 74 wiring diagram shows it near the instruments, not near the headlights where the horn and high beam relays are.
 
Chris, On my December 1973 build RHD CSi the horn relay and the high beam relay are located under the hood close to the battery on the left hand side of the car. There are more relays (five in all) arranged just above the hood release lever inside the inner wing behind the left hand "A" post and the glove-box which opens to reveal the fuses on the cockpit side of the front bulkhead. The low-beam relay is the rear-most one of these five. I will post some pics on Monday. Best, John.
 
Simon,

As promised I attach a photo of the relay position, as requested, and I apologise for the quality of the image.
 

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