main beam headlight problem 240z

[nospark]

All my lights work fine except the near side main beam (the offside works ok). I changed the bulb on the nearside but no difference. I am aware that the lights are switched on the earth circuit. Do the main beams have a separate circuit and more relevant do the nearside and offside lights have a separate circuit ? I ask this to rule out a fuse issue. Is it likely to be the stalk/switch combo unit ?
Your help would be greatly appreciated as I was planning an MOT tomorrow

 

[Rob Gaskin]

Do the main beams have a separate circuit and more relevant do the nearside and offside lights have a separate circuit ?

Have a look at your fusebox in the centre console

 

[nospark]

Rob, thanks for your input
I've swapped the left and right headlight fuses with no result. It's my understanding that the fuse holder connections under the fuse face plate can get dodgy ? If so, might be a long shot ?.

I've got Hellas H4's with what looks to be 5 wires going into the headlight bowl. I assume 2 to the small "parking" light bulb and three to the halogen bulb. I have just noticed that all these wires have extra taping about 5 inches from the headlight bowl and have probably been cut and reconnected at some time. (this makes sense as its the easiest way to remove the bowl from the car).

A previous owner has really taped and plastic channelled up all the wires so they are difficult to trace. I will be loath to start undoing everything. Its raining here so I'll get investigate this possible cut wiring tomorrow. Perhaps a connection has gone bad.

Could someone confirm that the stalk headlight combi switch activates the negative/earth circuit to BOTH the main beams at the same time ??? IF that is the case then I can rule out the combi switch as the source of the problem.
Ta for your help

 

[nospark]

thinking through my own problem. The power TO the headlights from the battery is on a separate circuit for left and right (each has their own separate fuse in the fusebox). But each power feed serves both the main beam AND the low beam lamps. Both my low beams are working so it can't be the power feed that's the problem. The "return" left high beam circuit (red/white) from the lamp connects with the "return" right high beam circuit (red/white) to then lead on to the dimmer/stalk switch where it is activated/grounded by the switch stalk (toggling between high and low beam). My right high beam works but my left high beam does not. Therefore the fault must lie between the left main beam bulb and where it connects in with the right high beam circuit.

I am not knowledgeable about electrics but have pieced together info from USA forums. Could someone please confirm that my above thinking sounds logical.
Thanks in advance

 

[SKiddell]

Often the fault lies in the column rotary stalk, there are a set of "seesaw contacts activated via a nylon "tits" these often wear or the contact bars oxidise, be careful when stripping down.......internals are small components and bouncy small springs.

 

[nospark]

skidell, thanks for your comments. If BOTH my high beams were not working then i would look at connections within the dimmer/turn stalk unit. However, I've now dug out a spare stalk unit and can see that the high beam circuit wires (coloured red/white) from the left and right headlights share a common wire input into the stalk unit. My nearside high beam doesn't work but my offside high beam does. Logic seems to suggest its not the stalk unit thats the problem

 

[Rob Gaskin]

How about running a wire from the working main beam across the car?

Then sort it later. Bit tongue in cheek tbh - have you got a wiring diag?

 

[nospark]

Rob,
Yes, I,ve got a wiring diagram for a 1972 240z (and a spare dimmer/turn combi switch which has been very useful to see what goes where). Plan of attack is to:-
1)Look under that tape 5" from the n/s headlight and check if its been cut/reconnected and the r/w wire has failed
2)Undo the connector block a bit further on and clean connectors
3)Check where r/w wire n/s and o/s circuits combine
4)take n/s headlight bowl off and test lamp along the circuit

Well I guess a reason I bought an old car is to potch about and learn new things. Happy days!

 

[AliK]

Nospark, I think your logic is sound and I'm willing to bet it's under the tape.

Do what Rob suggested and I'm pretty certain you'll prove it's the wiring close to the light. I had a few issues like that with hacked wiring by PO on mine close to the lights.

 

[nospark]

Victory. The fault lay with the plastic connector block located under the radiator. It was quite loose. Even though it has a good plastic sheath over it the 3 pins were corroded.

I post this for anyone else coming along in the future with a headlight problem. Might be of use

 

[Rob Gaskin]

Victory. The fault lay with the plastic connector block located under the radiator. It was quite loose. Even though it has a good plastic sheath over it the 3 pins were corroded.

I post this for anyone else coming along in the future with a headlight problem. Might be of use

Well done and thanks.