Hello all,

I recently had the pleasure of fixing the blend motors on my 07 FL2 SE.

At one point in the investigation my suspicions fell on the Central Junction Box (CJB) – P101, which is the one behind the glovebox.



I was too scared to open my own one up so I brought a cheap on of eBay to help me decided if I needed to open my own one.

I thought it would be useful to show you all what I found in case you need to look inside your CJB. I'm sorry if the pictures are in the wrong orientation but I couldn't figure out how to turn them round.

As the CJB is the brain of the car make sure you disconnect the battery and ensure you have left plenty of time for any capacitance to decay away before you start to play with it. It would probably be a good idea to ensure you are grounded, with a wrist earth strap, too, you have been warned

The CJB is in a white plastic housing which has 3 large coloured connectors (one blue, one brown and one green), one smaller 20 pin connector and one power connector which has just two large cables.



In the above picture the 20 pin connector goes to the right hand side of the green connector and the power connector goes to the left hand side of the brown connector just below the fuses.

If you look at the wiring diagrams these connectors are:

C1BP02A – The GREEN Connector
C1BP02B – The BROWN Connector
C1BP02C – The BLUE Connector
C1BP02G – The Two pin power connector
C1BP02H – The Twenty pin power connector

When you remove the outer white plastic cover you have this.



There are two Printed Circuit Boards (PCB) stacked on top of each other. You can see that connector H (20 pin) goes to the bottom PCB and connector G (2 pin power) goes to the top PCB.

You can also see that connectors A, B & C are actually two connectors in one housing. The bottom connector (it has more pins) with smaller wires goes to the bottom PCB and the top connector goes to the top PCB. This top connector has fewer pins but thicker wires.

With care you can separate the two PCBs but you have to remove the coloured connector housings as these act as a fixing for the two PCBs.

The separate boards look like this.



It is clear from this that the top board contains all the fuses and 9 PCB mounted relays and all the tracks are wider and the wires are thicker. So this one is just for all the power related connections.





The bottom PCB contains all the discrete components, Google tells me these are now called Surface Mounted Devices (SMD). Many decades ago when I did some electronics and you had resistors, capacitors and transistors, they have all got a lot smaller. The value of the resistor is now written on them! All the time I wasted memorising the resistor colour code 😊






The wiring diagrams shows us that the Central Electronics Module (CEM) (D316) is contained within the CJB and I think this bottom PCB is the CEM. As you can see from the above pictures if this has failed then, unless you have a very precise skill set you will have no chance of fixing it and a new one will be required with all the pain that goes along with that.

The top boards has 7 PCB mounted relays, if you type PCB into the search engine on the wiring diagram you find 11 relays. If you look closely Relays R270 and R271 are for the front and rear screen wash and they are a dual relay. Relays R257 and R258 are for the fuel flap lock and unlock and they are duel relays too and so there are 9 PCB mounted relays; which are all on the top PCB.

If these fail then, with care, the relays could be removed and a new one soldered in place, however, you will require a steady hand and some skill with a soldering iron.

I have tried to determine which relay is which but it was quite tough and I’m not confident that I am 100% correct.



Google tells me, from the serial numbers, that the two relays I’m pointing at, see picture below, are the dual relays.



If you need to get to the pins within the coloured connectors then you can remove the top black cover, there are four arbs at each corner, so gently open these up and the cover will come off.



You can then see the two connectors within the coloured surround.



The top connector, the one with the thicker wires which connects to the upper PCB with the fuses and relays, can be removed from the coloured surround, it is held in place by four plastic barbs, so, again, these need to be gently prised open and the connector comes out.



If required you could then remove the pins from the connector. First you have to remove the plastic locking plate. It is held in place by two plastic barbs on each side of the connectors. These need to be pushed in and then the locking plate can be removed.



Now you can remove a pin, however, this can be tricky and when you try and put a pin back it can be loose. If possible, the best option would be to connect a new wire to the tail of the old wire and test the continuity to the pin in the connector block.

The remaining connector is part of the coloured surround and can’t be removed. If you need to get a pin out then the locking plate needs to be removed. Yes, you have guessed it, the locking plate is held in by plastic bards. Open these and the plate can come out.



In the words of Mr Haynes refitting is the reverse of removal

I hope this helps someone.

Thanks Bob (Haynes?) - Good confidence inspiring Info. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)