Td5 D2 electrics - P38 Courtesy Light (2)

More research into fitting the P38 lighting unit. 

It arrived with bulbs already fitted but I decided to replace the tungsten bulbs with LEDs. Red in the middle with white either side.

Fortunately, the Rave copy I have also contains info on the Freelander1 and the P38 Range Rover, so I already had access to the wiring schematics.

This is the control board for the lights. The three push switches are at the top and the 4 circuit board terminals are at the bottom  ( I have already labelled them to correspond with the Rave schematics ).

The first thing I wanted to know is what does  the loom connector look like.?

  Rave and the web to the rescue... 

Three photos of  'C0355'.  It's a custom right angled board connector of a kind I haven't encountered before. It has 4 terminals available but only three (1,3,4) are used in the Freelander install.

The last photo shows one of the terminals removed from the connector body and it can be seen how it would 'pinch' onto the circuit board tails.

This photo from the Web is of a Discovery 'Metropolis' and shows the same connector in use. The three wires are the same ones used to connect the front courtesy lamp on every D2.

So, it would seem that all I need to do is get hold of one of these connectors and wire it onto Hx and connect up.....  As if...

Reading up on the Web about these connectors revealed a lot of common connection problems leading to inoperative lights. Corrosion of the Earth  
(black wire, terminal 1) connector is down to the flimsy construction and water ingress probably from a leaky sunroof. If this connection fails then none of the lights will work in 'manual' mode. 

Here is s close up of a connector terminal. It's construction does seem a bit fancy to me. I can easily see how even when attached, it's design will allow moisture access to the terminals. 

I can probably only source this connector from a breakers yard and assuming it to be in good condition I will still need to lengthen the wires or even remake the connections to the flimsy terminals. 

A better solution would be to solder 3 cables direct to the board terminals, insulate them with 'hot-melt' and run the cables to the installed front interior light on Hx were they will connect via a generic 3-way connector to the loom of Hx. .....  job done..

I got a bit carried away with the Freelander wiring schematics. Quite rightly so, because it closely resembles what is already on Hx. The big problem I was soon to encounter is that this unit is designed for the P38.

A big clue is in the P38 schematic. The same black connector is used but all 4 terminals are wired and connect to the board on the unit. The P38 connector has its own ID  number. . C329.

A photo of my notes from the P38 schematic. Terminals 1,2,3, have the same function (but not the same terminals)  as the Freelander install, and will be the terminals that I will use for Hx.

T4 on the P38 board runs straight across the board without connecting to any component on the board. It then feeds the black micro switch mounted off-board (at the top of the picture) which returns a wire back on to the board to then exit at T1. 

That black micro-switch is 'non-latching' and it's function is to generate an earth path via T1 which after 2 seconds causes the vehicle computer/bcu to 'deny' any further 'requests' for any internal light to operate until the switch is again held down for another two seconds.

This function is better explained in the P38 Drivers Handbook where it mentions an accompanying 'beep' from the dashboard console each time the function is selected.

I fail to see the benefit of this 'function' particularly as it denies the use of the switch to 'manually' operate the central lamp.

I need to work out how to achieve this before I install the unit on Hx. First thing to do is to strip-out that central black non-latching micro-switch and replace it with a latching one the same as the other two micro-switches.  Next will be to run a wire direct from the 'negative' central lamp contact direct to the switch and then replicate the return path from the current switch back to the board.

This should give me the functionality that I desire:

(1) - Automatic switching and fading of the central light via  BCU earth on T2
(2) - Manual switching of all three lamps via the micro-switches and earth T1
(3) - Constant 12v supply to all lamps at T3 

Can't help thinking with hindsight that I should have bought the Freelander version of this lighting unit. It uses a different design of circuit board but has all the functionality I desire inbuilt. And crucially, it has 3 latching micro switches on board....

Aside from the wiring issues, the other hurdle to overcome is how am I going to attach this unit to the overhead console in Hx...?

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