Tow Hitch wiring problem

Damien360

I am having problems with the wiring of brake lights. I have checked the wiring and it is good. I have got indicators working ok, main lights working ok but no brake light.

I have checked

the wiring on plug by continuity test on all wires was good

wiring on car by voltmeter from brake connection to earth (12V)

both bulbs have both filaments intact

checked each filament by swopping brake and main lights wiring

confirmed wiring is correct on plug for 7 pin connector

removed and re-seated each wire on plug

I should add the car is toyota avensis with toyota fitted hitch and plug. The part is a towbar fitted bike carrier by thule (with no reverse or fogs). Not a caravan but I figured you guys would be best to help as you would have to deal with hitch problems regularly.

I cannot imagine the bulb can pull down 12V input from car but maybe you can tell me if this is possible. All the cars lights continue to work correctly even when this bike carrier fails to work it's brake light.

Mods: if this does not belong here, please move it. Apologies for picture sizes but photobucket does not seem to have option to use smaller sizes.


Connector wiring diagram



My wiring from 2 angles





Left hand side wiring



Right hand side wiring

Wow shiny everything!
I reckon it's a simple matter of chasing 12v until it doesn't appear where you expect. You've done the hitch point, try the add-on brake light bulb contact. Anywhere it doesn't appear you have a broken core/connection between these two points.
Is that screw on the red line cutting through the insulation? ...maybe strip it down a smidge further.
Continuity test red core.

johnayo

Plug it into car and press brake. You should have 12v at red
Connection at bulb. If you have then check the earth.

Common ground, the other bulbs are working. Problem's in the red 'un.

paddyp

Looks like red is screwed down on the insulation that could be your issue there.

Damien360

Thanks for the replies folks. I will rewire plug again and let ye know.

Damien360

Damien360 wrote: »

Thanks for the replies folks. I will rewire plug again and let ye know.

I found the earth and red wire crushed under the sheath. I recut and re-wired.

All working now

Thanks again

I'd say you're almost too neat the sheath is only supposed to go to the terminals, everything inside ought to be exposed copper.
Good to hear you got it going. Kudos.