Reverse Lights not working

[DiveTramp]

Hi folks, I'm fairly new to Berlingos and I'm having an issue with reversing Lights not working. I'm trying to fit a reverse camera using the reverse light as a trigger. 
Bulbs are fine, I've shorted the Reverse Switch Plug but still no lights. I'm getting 3.5 - 4volts on these wires tho. 
It's a 2008 plate, 1.6hdi diesel with only 64,000 miles on the clock. 
I also can't find fuse number 33 which, according to Haynes Liars Manual, is for the reverse light and ECU (?).

[Sol]

Hi there,

Engine bay fusebox PSF1 , Fuse F1 (10A) is for the reversing light switch, but it also does the vehicle speed sensor so it if was blown, you would have no speedo.

The reversing lights do not light unless the engine is running, so you cannot test them alone with just the ignition on, and in reverse gear. Doesn't work.

Also, you should not connect anything to them, even a rear camera. You have to use an intermediate relay which draws less than 10ma as the lights themselves are powered from your BSI (Body Systems Interface) computer. If you blow those outputs, you have a world of hurt trying to repair that. The lights themselves are not fused, the BSI outputs drive them directly. I have my reverse camera powered from the rear 12v socket and on all the time with the engine. Works perfectly.

The low voltage you are finding is the Canbus test voltage supplied by the BSI to check if the bulbs blow. It has a warning system of bulb failure. That's why you are not supposed to connect anythign else to them that draws more than 10ma. Massive red & white warning sticker on the light harnesses at the rear tells you that.

Fuse diagram attached.


  M59 PSF1.pdf (Size: 262.49 KB / Downloads: 5)

[DiveTramp]

Wow! Thank you very much for that detailed reply. I'll hope that there's not too much "pain" and I'll cut that wire and just use another supply.
Cheers.

[Sol]

Did you check while the engine was running, and did you have reverse lights before? (I can read posts you've deleted.)

Just so we know the chain of events.

[Gryffindor]

What about using the gear stick reversing position sensor contacts?

[Sol]

The BSI doesn't turn on the reversing lights if the engine isn't running. Putting the ignition on and putting the gearbox in reverse has no effect unless the engine is actually running.

[Gryffindor]

Sorry, I meant as a feed from the gear selector to a relay feeding the rev cam, thus leaving the rev lights wiring well alone.

[Sol]

Sorry, I meant as a feed from the gear selector to a relay feeding the rev cam, thus leaving the rev lights wiring well alone.

Ah I get you. Sorry, that may have actually worked. I wasn't thinking in the same lane as you, sorry bro. 

Smart idea as usual!