Here's another problem I'm having in getting ready for Hay.

Have a new trailer, but the Moke is wired up a bit weird. Yes, I should probably change the Moke, but then I would need to change the Mini and the other trailer as well.

so, me thinks, easier to change the trailer.

After much fiddling and cursing I finally have everything working except brake lights.

I have power to the point for the brake lights on the plug on the back of the Moke.

I have checked that I have the plug on the trailer wired up correctly by supplying power from a battery and lighting up the brake lights.

But when I plug the two together, I get no brake lights on either the trailer or the Moke.

I thought it was a bad earth or poor connection, so spent ages cleaning everything, checking connections, checking the earth, but to no avail.

Taillights work fine. Indicators work fine. But no brake lights.

Any ideas?

Cheers,
Watto.

I work at a place that hires trailers so we get this kind of stuff all the time



are you running globes or LED lights? Flat or round plug?

To much voltage drawn with all the lights on?

if you have lights on the car and on the trailer when tested independently
i'd be re-checking your plug for a mismatched connection.

Try using a plain piece of wire to test the brakes between the two plugs. you can also use this to run your trailer brake of you car blinkers as another test.

Alternatively unhook the brake wire from both plugs and twist them together and see if that works.

people often overlook that a pin in the plug is pushed in and not making a connection too.

Good luck Watto

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1962 850,Frog

Sounds like the plug to me. Go and buy a new one, there cheap.

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Have a Nice Day.
If already having a nice day please disregard.

Have you checked all of the connections inside the plug? they're usually the first to go.

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Simplify and add lightness

Rather than depend on the trailer chassis as a ground, run a wire all the way from the ground terminal on the plug.

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Thanks guys.

The trailer plug is new. The Moke plug is old, but has been working fine on the previous trailer.

I have pulled all the plug apart and cleaned all connections, made sure all wires are in good condition and checked everything is together properly.

I have tested the brake lights on the trailer with power from an alternate battery and the wiring and lights appear to be fine.

Wiring directly from the Moke brakes wire to the trailer wire gives the same result - ie no brake lights on either, so I don't think it is the plug.

I am using globes, not LEDs.

When the trailer is not connected, the brake lights on the Moke work fine and the brake lights on the trailer work fine. Connect them up and nothing on either.

Still frustrated.

Cheers,
Watto.

There's nothing for it but to chase it out step by step, something which will identify the problem in a few seconds.
Grab your multimeter and test the back o the plug for 12 volts to the chassis, if its not there, its one or the other plug causing a contact issue, or the terminal in the trailer plug.

Test the bulb socket for twelve volts, if its not, blame the trailer loom brake wire. Check both sides for 12 volts, they usually loop out of one side and then carry onto the other, so if one light does not work the fault may be hidden in the other.



Clean the bulb contacts in the lamp fittings as well.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

sounds like a short circuit in the brake light circuit on the trailer to me. With the plug disconnected, check for a dead short between the "live" terminal on each globe/bulb holder to the trailer chassis.

Good luck with it mate.

_________________
1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

Is one of then wired up with pos earth and one with neg earth? would that cancel out the voltage at the brake lights?

But the other lights work so I'm not sure. I hate electrickery.

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Simplify and add lightness

No. Filament bulbs don't have a polarity.

My bet is on a bad earth, either on the moke's plug or on the trailer.
Is the trailer earth pin actually grounded to the chassis?

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Too many cars, and too little time.

my moke did exactly the same thing when i tried to connect a trailer up, only for the indicators not brake lights.. ended up being a dirty connection between the fuse and the holder. cleaned them up nicely and it worked. That's probably not going to help you much, but atleast now you know you're not the only one who has had this problem

Problem solved folks.

Thanks for all the suggestions. Some I had already looked into, others helped give a few new ideas, but the winner is.......

Nobody.

Well, me actually.

While checking out all the connections at the lights on the trailer, and getting ever more confused as lights did all sorts of strange things, I accidentally touched the wire for the brakes to the wire for taillights - while the taillights were on. In theory, nothing should have happened except the brake light coming on, but I got a spark.

So, I touched them again deliberately and got an even bigger spark.

Hmmmmm......me thinks one of the wires is earthing out somewhere, but it can't be the taillights, as they were working.

Must be the brake lights.

Starting from the front of the trailer's wiring I began to trace the wires back and eureka, there it was.

When the trailer was assembled, the wiring harness had got caught between two parts of the the trailer, and squished between them - on a sharp edge. The edge of the metal had gone through the wiring harness and shorted out the brake wire only.

Phew - 4 hours work for what should have been a ten minute job - and Lucas, the Prince of Darkness wasn't even involved.

Just some bloke called Murphy.

Now, I just have to sort out this hydraulic handbrake - and I've got a couple of ideas, but I won't be able to do anything until after Hay. Oh, well. So much for having a good handbrake for Hay.

Cheers,
Watto.

I've been telling myself "next Hay will have a hydraulic handbrake". It's now Hay in 40 hours, and i've just finished getting the car WORKING.

Ohwells... next year, and hopefully a lot of practice before.

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as fas as I'm concerned, I won

_________________
1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

Obviously not fine!

_________________
Have a Nice Day.
If already having a nice day please disregard.