My brake lights don't...(light, that is) (1 Viewer)

Bryan

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Jul 19, 2007
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Hello all you electrically mined people in fun land :thumb:


The brake lights on my Rv don't light. They used to, but now they don't.

There are two switches on my brake pedal, one has two wires and the other has three. I think the two wire switch is for the cruise control cancel operation but I may be wrong.

The three wire switch has one wire which I've been told is to do with the transmission (?) and a permanent live and when I depress the switch the 12v goes down the third wire. So I don't think it is the switch.

All fuses are fine and the bulbs are fine too.

I have a tow socket which I think is scotchlocked into the light clusters. A light board on this socket also fails to light it's brake lights.

If I connect my toad and apply it's brakes, the RV brake lights illuminate also - hence my knowledge that bulbs are okay.

I had hoped to trace the wire from the brake pedal to the light clusters and to this end I bought a tone generator and wire tracer. I have put the tone generator on the wire that get's 12v from the switch mentioned above (when switch activated) but I can't seem to trace it anywhere - even away from the switch.

I don't have a chassis manual unfortunately (workhorse 2001)

Can anyone offer any suggestion?

(Note: Possibly unrelated but my cruise control also stopped working at about the same time)

TIA

Bryan
 

davejen

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Hi, Bryan if I were you I'd check the scotchloks - they're notorious for being crap and not working properly. If you can replace them with proper connectors 1 at a time so you don't get them mixed up. Hopefully this should solve both problems as the c/c won't be getting a signl so won't work.
Cheers, Dave:thumb:
 
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Bryan

Bryan

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Thanks Dave,

Because my toads brakes activate the RV brake lights, surely that means the scotch locks are okay?

Also, wouldn't a nasty scotch-lok failing just take out the one light, not bboth + the high level?

The scotch-loks are in the light clusters...

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pappajohn

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hi Bryan,

does the two wire switch work ? power in and out when pressed or possibly earth return from lights through switch to earth.
easiest way to check....remove both wires from the switch and join together...if they work its the switch, if not its a fuse or wiring fault.

i would expect the 3 wire switch to be for the cruise and transmission switching (both circuits in one switch) and the 2 wire switch for the brake lights.

saying that, the yanks have some strange ideas of lights and wiring.
side lights and tail/brake lights flashing for indicators etc.:Doh:
 
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davejen

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Thanks Dave,

Because my toads brakes activate the RV brake lights, surely that means the scotch locks are okay?

Also, wouldn't a nasty scotch-lok failing just take out the one light, not bboth + the high level?

The scotch-loks are in the light clusters...

Probably, so look then at the feed from the switch, get someone to press the brake and then see if there is a feed to the lights, if not then you'll have to check the switch again- is the 3rd wire live when switch operated? and where does it go- it may be to the indicators if they have been changed to amber.
Dave:thumb:
 
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Bryan

Bryan

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Probably, so look then at the feed from the switch, get someone to press the brake and then see if there is a feed to the lights, if not then you'll have to check the switch again- is the 3rd wire live when switch operated? and where does it go- it may be to the indicators if they have been changed to amber.
Dave:thumb:


Am I missing something? Why would a wire from the brake pedal switch go to the indicators ?:Eeek:

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davejen

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hi Bryan,

does the two wire switch work ? power in and out when pressed or possibly earth return from lights through switch to earth.
easiest way to check....remove both wires from the switch and join together...if they work its the switch, if not its a fuse or wiring fault.

i would expect the 3 wire switch to be for the cruise and transmission switching (both circuits in one switch) and the 2 wire switch for the brake lights.

saying that, the yanks have some strange ideas of lights and wiring.
side lights and tail/brake lights flashing for indicators etc.:Doh:

I'm sure the brake lights and indicators are the same light so I think they are wired through the brakelight switch as pappa says.
Dave:thumb:
 

haganap

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Sorry Bryan, But I just can't resist it




HAVE YOU CHECKED THE FUSES:ROFLMAO::ROFLMAO::ROFLMAO::ROFLMAO::Doh:



In fairness though, i think a long trace through the wiring starting at the brake switch would be a good start. Find where you are live to from the begining of the switch and then start tracing through. Tough job me thinks, also a long shot would be if your tow equipment has shorted something.

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Bryan

Bryan

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Thanks John and Dave for the help...Paul? You can just shutup, alright :ROFLMAO::ROFLMAO:


I have it on good authority that the three wire switch is the brake light doofer...but you make a good point about the indicators of course...Originally the RV when in the states will have been wired for flashing brake/tail lights for the indicators. Altered in the UK and that will be why some of the wires are scotch-lok'd

I'm leaning towards a dodgy/broken wire rather than the switch. The switch with three wires, when activated, allows 12v through.

I now think the other switch (2 wire) is a lockout for the gear lever (Won't move out of park unless brake pedal pressed.

I just wish I had the chassis manual - I'm sure it would help :Doh:
 

Boo

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Is it relay assisted? have you checked them?

Just a thought............good luck :thumb:

Boo

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PenelopePitstop

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..Paul? You can just shutup, alright :ROFLMAO::ROFLMAO:


Hmmmm - think I may just have to publish the photos of you upside down on your driver's seat in Couhe !!!!! :ROFLMAO:
I'm dong a good line in blackmail after France!!!!

He he he!!:ROFLMAO::ROFLMAO::ROFLMAO:
 
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Bryan

Bryan

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Right, I've been upside down again...:Doh:

There are two switches on the brake pedal...One with two wires that activates a solenoid(!) that prevents the gear lever being moved unless the brake pedal is pressed...This works fine.


The other switch has three wires. 1 x white, 1 x orange and 1 x purple.

I've been told that the purple wire is something to do with the transmission...

The orange measures 12v all the time.

With the ignition off the white measures 0v with the brake off, 12.4v with it pressed.
With the ignition on the white measures 4.4v with the brake off, 11.6v with it pressed

Voltage drop aside, this indicates to me that the switch is working (assuming that the orange IS the feed and the white IS going to the brake lights.

BUT my brake lights never light :cry:


Does this help anyone to help me? :thumb::cry::thumb:

Bryan
 

haganap

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Ok Bryan, I will shut up about ya fuses.

Ok, You have power out of the switch. Which blows my theory of the solonoid.

Have you checked power at the lback lights on both side? I know we checked the bulbs but did we check the circuit at the bulb end? if so and there is no short at the tail light holder then somewhere in between your problems surely exist. I have acdcdave staying on my drive tonight with staging lady in there new van. They have just gone to bed but dave is an electrical engineer, I will ask him in the morning if he can make any sense of it.

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dazzer

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If i were you id stop wasting any more time trying to find the fault and just fit a new wire from the white brake switch wire to the rear brake lights or even try and find the original wire fitted when it was converted to UK spec and connect a new feed onto that :thumb:

You could be there for hours and having no idea what does what a new start could be the easiest solution all round :winky:
 

pappajohn

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do your brake lights usually work with ignition off ?

if so do they work now with ignition off ?

you're getting a voltage in the white with ign off so it should light the lights.

the 4.4v in the white with ign on is a puzzle as is only 11.6 with ign on.

ign on will be a higher battery drain so the 11.6 isnt too worrying but it seems there is some kind of backfeed from the ign to the switch get a 4.4v reading without the pedal pressed. (brake switch open)

what readings are there if the engine is running ?
 
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quicksam

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Earth fault

Hi Bryan,
my therory is that you have a loose/broken earth wire on your van.
When the toad is plugged in you are completing the circuit through the toads circuits and the vans lights will work.
Worth looking eh ?

cheers
Sam

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Bryan

Bryan

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Thanks for the replies ::bigsmile:


Ok Bryan, I will shut up about ya fuses.

Ok, You have power out of the switch. Which blows my theory of the solonoid.

Have you checked power at the lback lights on both side? I know we checked the bulbs but did we check the circuit at the bulb end? if so and there is no short at the tail light holder then somewhere in between your problems surely exist. I have acdcdave staying on my drive tonight with staging lady in there new van. They have just gone to bed but dave is an electrical engineer, I will ask him in the morning if he can make any sense of it.

Cheers Paul :thumb:

If i were you id stop wasting any more time trying to find the fault and just fit a new wire from the white brake switch wire to the rear brake lights or even try and find the original wire fitted when it was converted to UK spec and connect a new feed onto that :thumb:

You could be there for hours and having no idea what does what a new start could be the easiest solution all round :winky:

I have considered this but I cannot be sure that the white wire goes just to the brake light directly...If I put a new wire in I may bugger summat else up :Doh:

do your brake lights usually work with ignition off ?

if so do they work now with ignition off ?

you're getting a voltage in the white with ign off so it should light the lights.

the 4.4v in the white with ign on is a puzzle as is only 11.6 with ign on.

ign on will be a higher battery drain so the 11.6 isnt too worrying but it seems there is some kind of backfeed from the ign to the switch get a 4.4v reading without the pedal pressed. (brake switch open)

what readings are there if the engine is running ?

Will check with engine running tomorrow...
Can't remember if they work with ign off - but suspect they do, usually, but at the moment NO brake lights work...On the RV or the toad (scotchlok'ed from light cluster methinks.)

Hi Bryan,
my therory is that you have a loose/broken earth wire on your van.
When the toad is plugged in you are completing the circuit through the toads circuits and the vans lights will work.
Worth looking eh ?

cheers
Sam

when i press the brake on the toad it sends the power up the cable to the lights via the scotchlokd connections so wouldn't the bad earth stop that working too?

Thanks
Bryan
 

pudseykeith

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hi Bryan. Quicksam's advise seams sound. If the earth on your brake lights is not existing, when the toad is attached and the brake peddle is pressed the earth on the toad is completing the circate and so lighting the van brake lights . With problems like this always look for the obvious. Kiss - keep it simple s :winky:
pudseykeith :thumb:

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Oct 15, 2007
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Switch?

My experience, having had to muck about with the wiring on both of ours is yes the norm seems to be chop the feed out from the switch and re run the stop light wiring to overcome the indicator/stop light US wiring and as above/previous if memory serves it's the white wire. If you've lost cruise control also that would to my mind point to a switch/initial feed, or possible earth problem as this is a safety feature for cruise, try having your foot on the throttle and stoping any vehicle:Eeek:

IF you're confident, trace the three stop switch wires and try a switch, and a low amp fuse, to switch the wires and see what you get? Momentry here just in case, ie have an assistant, RV wiring, especially on the convertion side is usually pretty heavy guage, this is the caveat bit by the way, so as long as momentry and fused you shouldn't do any harm if......

On the earth question, again a good theory. Have you tried a full lighting check, indicators, side, stop, reverse etc etc and various combinations as usually, again my experience, at some point you'll get the disco effect if the/a earth is missing as those little electrons will find a way of getting home, hence disco effect?
 

Andy 01424

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Brake lights work when toad is hitched ,as toad lights will be earthed probably on the frame,when hitched you are creating the earth circuit,,so suggestion would be is to take lights out of the RV connect a tempray earth somewhere [tow ball see if they work then,eleimnates bad earthing problem:winky:
 

haganap

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Go to any good auto electrician who will locate the fault in seconds and rectify it in minutes.

go to any bad one and he will locate the fault in hours, rectify it in days and charge you by the second:thumb:
 
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Bryan

Bryan

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WOO HOO!

They work!!!



:clap::rollonfloor::clap:
:yeah::rollonfloor::yeah:


Following some more diagnostics at the Morecambe Festival meet (thanks Brian, oh dweller of hills) and some logical thinking and analysis (thanks again Brian) I managed to find a loose conection under the dash :thumb:

It was actually a connector that was working loose so it may also have fixed my cruise control problem too.

So not only do I have working brake lights but I know more about the wiring in my RV too ::bigsmile:::bigsmile:

Thanks to all for your help and advice and special thanks to Hildweller for his dogged determination :thanks2: :notworthy:



Bryan
 

Black Five

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Brake lights

Well done Bryan, I knew you could do it. I'm sure it will sail through it's mot now:thumb:
 

PenelopePitstop

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Just thought I'd share some photos with you all of Bryan trying to fix his lights when we were in France! :ROFLMAO::ROFLMAO:
Oh and one of the 3 would be mechanics!!:Eeek:

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