Does anyone know where the Body Control Modules are located?

I'm getting faults due to loss of communication with a body control module on the CAN bus - SDD advises to check the connectors on BCM_2 and BCM_5, but I can't find any information on where they are.

Cheers,
Jon

 

If you peruse the attached you will find circuit diagrams for the module networks CAN & MOST. Word searching for bcm_2 shows its location but searching for bcm_5 doesn't find any matches. Anyway the circuit diagrams should help you.

 

Hi hafren,

Thanks for that - looks like bcm_ is used for the battery connections on these drawings, but SDD seemed to be referring to different body control modules. I'll have another go with SDD to see if there are more details given that I can use to cross reference its advice to the module names in the wiring diagrams.

Do you know if there is a drawing that shows where each of the modules is physically located in the car (I've found drawings for other Jags, but not the X351)? I may just have to use the sequence of the modules on the high speed CAN bus, and the wire lengths given to work out roughly where each module could be?

Cheers,
Jon

 

Sorry I looked for a module overview but couldn't find one.

 

Thanks for looking - I'll start making my own overview as I find bits and post it back in due course...

 

Did you find this module location ?

 

Which module are you looking for? The module names used in the wiring diagram are different to the module names used in the SDD module status graphic, which are different to the module names used in SDD's fault finding instructions... not really very helpful!

The most useful thing I've found so far is that the order of the modules on each bus is given by the wiring diagrams, so once I've found a few I should be able to work out where others might be (plus some level of common sense about where things should be).

 

BCM - Body Control Module? Did anyone find its location? Is it in the trunk ?

 

The current crop of Jags don't have separate body control modules anymore. The functions that used to be controlled by them are now built into the intelligent fuse boxes. In the X351 the body functions are all managed by the central junction box located centrally behind the rear seat back. It sits on the ends of both the medium speed and high speed CAN networks and provides the end of line resistance that is used by all the modules to detect an open circuit.

SDD is quite vague when it comes to the names of modules, and tends to use historical abbreviations which are not always the same as the schematics, as you have found.

BCM in the schematics appears to be used exclusively for connections in the battery junction box. That is basically just a distribution point for the main power supply circuits, rather than an intelligent fuse box, and does not appear to be monitored on the CAN networks.

BCM_2 is the 50A fused supply to the central junction box between C4BF01F/1 (battery junction box) to C3BP01D/21 at the central junction box.

BCM_5 is not coming up on TOPIx but may be mislabelled in the SDD. There are only 4 main power supply circuits to the central junction box.

What specifically is the observable fault you are diagnosing? It might help to narrow it down. Whilst it is entirely possible you have a fault with the battery supply to the central junction box, unless there are other symptoms that likely isn't what you are looking for. I suspect that SDD uses BCM/body control module to refer to the central junction box as it assumes the roles of a body control module. If you have CAN comms issues with that then there are tests you can do to see if the fault lies within or outside the fuse box. (You should get near to 120ohms across the twisted pair with the battery disconnected.) The connectors to that fuse box are surprisingly delicate for such big connectors and I chased a fault in my car that ended up being a pin in one of them that had been pushed back into the housing as the locking clip only makes partial contact with it. It may be worth you disconnecting each in turn and checking that the pins are all located correctly in the housings (pull back gently on each wire in turn and look for any movement).

Are you able to screen grab the bits from your SDD session that show the issue?

Diagrams of the connectors and a vehicle-wide diagram are attached. 'Detail C' is the central junction box. 'Detail E' shows the battery junction box to the left of the diagram.

 

Looks like its here: DETAIL D REAR RH QUARTER

 

Thanks Xdave! The reason why i ask. Is because my steering wheel does not come back to parking mode after i drive car faster. Steering wheel is very light in the morning. But it wont be light later. Pump is new. And i see there is a recall - BCM has to be reprogrammed. I went to the dealership - they said all is good. But i dont believe them. So i wanna buy 2013 year BCM and try it on my car.

 

'Detail D' shows (clockwise from top) -
- Air suspension module
- Rear junction box (intelligent fuse box that mainly manages chassis functions)
- Rear diff control module

'Detail C' with the three big locking connectors on the front, two on the top and three on the rear controls the body functions.

The junction boxes are highly VIN range specific, so a 2013 won't work in a 2011 car as there are some big changes to functionality at that time. The car probably won't start.

Regarding your steering issue - as you know the software loads various maps depending on speed which affect the lightness of the steering. Your symptom sounds like it works as expected first thing in the morning, and it transitions to the high speed mapping ok, but after driving at speed it no longer returns to the low speed mapping. Did the dealer replace the pump because of DTCs, or proactively while trying to find the issue?

The central junction box (afaik this is the body control module) can easily be reflashed through SDD by selecting a suitable symptom and following through the normal process for reflashing a module. Do you know if the dealer actually did that (I think from your reply that they didn't do so).

Is the TSB you mention the JTB00260NAS2 attached? It covers the reflash procedure using SDD.

 

Exactly, it does not comeback to the low speed mapping. I replaced pump myself before that. The steering wheel with old and new steering pumps - behave the same way: light in the morning, but later on wont comeback to the low speed mode. Dealer did not flash or change anything, i think they are too incompetent for that. They said: my car does not show in the diagnostics that it has to be reprogrammed. They did nothing. So i didnt bother fighting with them. I now know the location, so just gonna drive up to the junk yard, get a 2013 BCM, pull out wires from my BCM, connect to a new one and see if it work, and if so if the steering will be better.

The BCM module i think is not the central junction box. It is just on the left to the fuse box which is in the trunk. You will see 2 modules put one on each other. You gotta open that carpet little bit, and you will see. The BCM is the one closer to the body. I recognized it by checking BCM pictures on net and i see exact one is in the location i explained.

p.s. i found 2 wires going to the steering rack, they go to that actuator or valve which controls the flow of the fluid therefore making steering wheel light or heavy. also known as servotronic in other cars. So i cut 1 of them and the steering wheel became very heavy. I connected it again and it became light again. All this i did while cars engine was running.

 

 

That module in your photo is the continuously variable damping module from a 2013-14MY X351 (aka the Integrated Suspension Control Module or ISCM). Earlier model years used two slightly different modules in the same location, but they appear to use integrated modules across the range now. Things like that are often described as body control module/BCM as it is a catch-all term, like ECU is used to describe various modules.

The Servotronic system/software that controls the speed sensitive steering is part of the instrument cluster. The TSB above only mentioned BCM (the generic term) so could well be referring to the IC software being reflashed. Either way, if your dealer enters the symptom into the diagnostics software and follows the prompts to update the software you don't really need to know which physical modules are being updated as it takes care of it for you. Although that TSB is for NAS vehicles, it's a zero-loss action to try (apart from the $$ for the diagnostics time).

 

You are right. Yeah, thats what i meant - they reflash it - nothing to loose. But i guess they were just incompetent to do that. They connected a PC and it did not show that a reflash is required. But it could be done anyways.

 

Gal butu galima gauti Jusu kontaktus pasikonsultavimui, buciau labai dekingas.

 

Arturas ????

 

Welcome to the forum Arturas,

I believe your post is written in Lithuanian and translates into English as "Maybe you could get your contact information for consultation, you were very deceiving" .....?

We are an International forum and the common language used is English. If you wish to participate, please use English.

Graham

 

Hi Guys,

New here, trying to get the grips with the electrics on the car.
Just following this thread but I'm wondering where the bcm module is located for the xf 260. 2016 model year. (Manual)
​​​​​Currently changed from a flat battery to a new one and now all sorts of gremlins are happening including no driver mode select and windows not working!?! Diagnostic pulls up 262 errors and nearly all points to BCM. I'm guessing it's behind a carpet somewhere? Any help be appreciated.

Thanks, Ian