Intermittent rear light fault

[Chuffer]

I think I have just discovered the possible cause of the recent occasional battery drain on my 1980 C3 . My neighbour called me tonight to say that the rear lights were on despite the car having the ignition switched off and car all locked up for the night . This can only be an intermittent fault as I have not noticed it before . Any thoughts ?

 

[teamzr1]

Did you ask which rear lights were on ?

Could it be the brake lights and the switch on brake pedal sticks closed state randomly ?

 

[Chuffer]

Did you ask which rear lights were on ?

Could it be the brake lights and the switch on brake pedal sticks closed state randomly ?

I need to get someone to stand behind the car to check if its brake lights or rear lights when i press the pedal . I would have thought that the circuits should be dead when ignition is off ??

 

[Oneball]

I need to get someone to stand behind the car to check if its brake lights or rear lights when i press the pedal . I would have thought that the circuits should be dead when ignition is off ??

I believe brake lights and horn are both always live. It’s very easy for the switch to be out of adjustment so they’re on.

 

[Chuffer]

I believe brake lights and horn are both always live. It’s very easy for the switch to be out of adjustment so they’re on.

Thanks guys for the quick replies . How odd that the brake lights are live when ignition is off , don`t see the point in that ! As the problem is intermittent it rather does suggest a sticky switch .
I will have a poke about today and what`s going on .

 

[Roscobbc]

Most American cars of the period had 'live' brake lights.

 

[Chuffer]

Most American cars of the period had 'live' brake lights.

I am sure there was a good reason but I certainly can`t think of one !!

 

[Chuffer]

I have depressed the brake pedal several times and checked the switch and it appears that the switch sticking was the problem . The bracket that holds the switch in place was solidly fixed which is good news as would be a bugger to get to the bolts to tighten up . A generous dose of WD seems to have cured the sticking but I will monitor things closely for a while .

 

[teamzr1]

As the drawing shows, hazard/stop/brake circuit is hot at all times so they function when the car is broke down
and lights help show car to traffic

 

[Chuffer]

Thanks for the wiring diagram Team ZR-1 , it will be useful for future reference . I can see now the reason for stop lights and rear lights being `live` ( UK speak for `Hot` ) . UK and European cars use the indicators as hazard lights so the wiring is separate from the tail lights / brake lights .

 

[teamzr1]

You're Welcome

You can see that from that 20 Amp fuse supplies +12 to both the hazard switch and to the stop switch
so both are hot all the time to assure vehicles behind could see the C3 stopped ahead even with ign key off

With hazard switch on then if also supplies the +12 to same lights as stop lights
and if off, the stop switch still gets the +12 hot all the time

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