Technical Off side brake light not working, bulb ok

[hairyone]

Hi my daughter’s 2009 fiat 500 has the offside rear brake light not working. High level and near side ok.

Tried a few bulbs none work but all good.

Bulb terminals show 5V all the time whether brake pedal is up or down.

What should I test next, fuse? earth point?

Could a damaged wire in the gaiter to the tailgate cause an issue?

 

[Derbyfella]

You wouldn’t have volts if you had a fuse blown.
Have you looked at hatch wiring,

 

[John202020]

Not the hatch wiring
Try this test first.
Turn on headlights
Turn on rear fog light
Turn on right indicator
Any strange going ons either side?
Try removing and plugging in the connector on the rear of the cluster several times
With a helper pressing the brake the green/yellow stripe wire should be +12v on the off side, if not trace the wire back to a non flexed part say in the boot, use a knife blade to push through the insulation to test the voltage, it's not uncommon for the wire to fail internally.
Check the quality of the earth though the first test should show this up.

 

[hairyone]

Thanks JohnJohn,

Next time I have access I will do that.

I did have all the lights an indicator on wit my daughter on the pedal intermittently, and it all looked fine but I'll test again.

Usefuil to know thw wire color, I'll trace it back!