[Dave57]

Yes plugging in the trailer plug does disable the reverse sensors, never checked the lights functionality when plug is in - I did however as stated above disconnected the trailer plug loom to return the circuit to normal. Bulbs checked ok. I fear that the circuit is ECU/Canbus controlled.... but is hard to find a circuit diagram, not quite ready yet to fork out 50 notes for a VIN related online manual but may have to - before going into a dealer for diagnosis.

 

[Dave57]

Can you identify the pins used for the reversing lights

That's part of the problem - they are part of the rear light assembly and it's a bit cold out there to dismantle the rear cluster; trace the RL track to pin/socket number then the same on the loom plug...

I will have to dress for the North Pole temperatures tomorrow and have a go, assuming the forecast snow holds off

 

[Dave57]

Go back to your gearbox switch and see if manually operating it puts the lights on.
These switches can be position sensitive and even half a turn too far or not enough can bu55er up the system.

Yes done that both connected and unconnected with a meter. Switch operation went from open to closed on actuating button being pushed in but did not switch on the lights.

From another thread with a MOT fail due to rear fog light fail appeared to mend itself after disconnecting the battery and reconnecting. I might give that a try soonish.

 

[Dave57]

I perhaps didn't explain too well.
If I am right, the switch acts not only as a reverse switch but also a neutral position sensor.
As such it has 3 positions, unactuated, part actuated and fully home.
You should be able to check, ie open poles, one closed, the other (or both) closed

Mmmm...
A switch circuit diagram on an ebay add. put both output poles level. I took that the second output is for the u-sonic sensors. Neither are functioning.

Next time I take the switch out I'll investigate....

 

[Dave57]

There is a bleeper cancellation switch (auto resetting with ignition off) on the dash facia. The sensors would need their own power feed an case of both bulbs blowing.

 

[Dave57]

I can't find a diagram ATM but 3 poles often means 3 positions and switch fail is more likely then system fail (no guarantees)

Here is the diagram I found...

 

[Dave57]

It stopped raining so I popped out did a battery disconnection and a re-boot no change.

So removed the switch...

Now holding the switch as in the diagram above button depressed - RHS to middle pin closed 0.006
LHS to middle pin open, released it slowly to see if it made contact at a different position - it remained open unlike at the weekend when both closed 🤔. I removed the switch so as to order the right one and having checked size will get one in the post and keep fingers crossed..🤞

I will report back next week once fitted.

Thanks all for the discussion -

 

[Dave57]

I now have working reversing lights and sensors. The job took a while as the first replacement reversing switch for the gearbox effected a single bleep when tested and that was it, - no lights and sensors not responding. Since it was an eBay cheapy I took Dremel to it and stripped off the top plastic shroud to find one of the spring contacts was bent out of shape. The attached photograph shows the 2 contacts, on the left the spring makes a momentary contact halfway along the switch travel. On the right the spring contact should remain closed while the actuator is pushed in all the way. I obtained a 3rd switch from Amazon which looked more like the original.

Note: I painted the green onto the contact actuator to clarify its shape. IMHO i expect the LH momentary contact is to tell the cruise control system to disengage when a gear change is made.

On manual testing before installation there was no activity. Deciding to check the under bonnet fuses again – unbolt and set aside the radiator header tank, unbolt and remove fuse box cover, release and turn over the upside down unit with multiple socket connections and a quantity of unidentified fuses. I repeated checking all of the fuses eventually finding a fault with the hardest to reach in the middle of all the plugs and cables. It was a 10 amp and had blown, replaced it using a pair of long nosed pliers. And retested everything worked. Hurray!

Re-assembled the fuse box and cover, tidied up, job jobbed.


For future reference;- if your Renault Master reversing lights fail then check the under bonnet fuse box, fuse F12 – a red 10 amp fuse near the centre of the upside-down fuse and connection panel. The panel is cream plastic and the fuse identities are about 6pt in size and of course cream on cream, shining a torch sideways can help.

Thanks for the responses above I got there in the end...
David

 

[Dave57]

Great result and I admire your tenacity.
Doesn't pressing the clutch tell the CC to stop?
So under normal driving use is the switch is as shown, relaxed?
Does the switch have 2 working positions depending on what gear you're in or is is momentary? (I'm asking because of an earlier comment about difficulty in setting it up).
It looks from the photo that one pin should always be connected to chassis? (the LH as shown).

1. CC will stop if either the clutch or brake pedals are depressed, but if the drive is disconnected by just shifting to neutral then the engine could over rev. The LH momentary contact would give a signal to the CC in such circumstances if that is its function -- not that I've ever tried it or going to
2. The LH switch in the photo is held open -- it closes when it drops into the V notch of the actuator, sorry the gap is not very clear in the photo due to the slight (sight) angle.
The RH switch closes once the actuator is pushed further in. It also has proper contact points indicating that (to me) it probably carries some loading. Similar to contacts in a petrol engine distributor - remember them??

David

 

[Dave57]

Nice one Dave, well done.
View attachment 195452

And thanks for the switch picture.
That was what I was trying to explain.
As the switch is pushed in, one contact makes and if pushed further, the other.
Inside the gearbox are selectors that will push the switch X amount when in reverse and Y when in forward.
So it can show three states, neutral, reverse or forward.
Nothing to do with Cruise Control but rather starting conditions and reverse light.

I read what you were getting at, the LH only makes contact at the halfway point and opens again in the reverse - pressed fully in - position. As in 2. above I'm not not going to try a 'live' test....