Not trying to teach you to suck eggs but you have done all this with a fully charged battery, even a small drop in voltage will upset things....?

And have you checked all the ground points you can find....?

Just a couple of free things to check....  Pete
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
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btbtbtbt318 wrote:

I have picked up a little oscilloscope for some more deep diving into the CANBUS operation, and what I think I've learned is that the bus reading short circuit to itself/ground when the system is "awake" is normal when just checking with a multimeter?

Checking the bus with the oscilloscope is telling me that it is at least functioning somewhat as expected, with CAN HI and CAN LO showing opposing signals centred around 2.5 volts. The signal seems very busy/messy but that might be a limitation of the cheap scope I'm using. Looks like this:

Haylands wrote:

Not trying to teach you to suck eggs but you have done all this with a fully charged battery, even a small drop in voltage will upset things....?

And have you checked all the ground points you can find....?

Just a couple of free things to check....

hmallett wrote:

I don't know if this is relevant, or just a limitation of your oscilloscope, but all the can bus signals I have seen (and I've only seen them on YouTube videos) are much more on/off than what is shown in your screenshot.

Mikey wrote:

Personally, I'd be concentrating on these codes...

Strong agree and that's where I'm spending my efforts at the moment.

Between the two P0504 codes and C1A96 brake switch circuit seems a consistent theme. My circuit behaves consistently between the switch that came with the car (original BMW) and a replacement one (aftermarket). All of the brake lights work when you press the pedal as you would expect.

BUT, the behaviour I have doesn't match up with the wiring diagrams quite right. The 2006 manual shows this:

Which is:
Purple/yellow 12v supply from fuse 9 with ignition on (tested working)
Purple/green signal to ABS module, normal OFF, switches ON with brake pressed (tested working, notable 1v drop over both new and old switches for some reason, tested at ABS module connector and signal gets through with no further drop)
Brown/black to earth (tested 0 Ohms to earth point, earth point is good)
Blue/red signal to ABS module, Light control module and ECM, normal ON, switches OFF with brake pressed

BUT the blue/red earth signal switch shows normal ON in the diagrams, where mine is normal OFF. This is consistent across two switches. For what its worth the blue/red has good continuity to all three modules it goes to.

This is the earlier little black switch XKB000021/22, not the newer blue/white switch which I also bought accidentally.

Now this 2006 manual says all over the bottom of it "VIN 239036 onwards". Mine is 235xxx as an early 2006 build, so maybe the diagram doesn't match?

I've got diagrams for 2001 and 2005 models and they both show this:



Difference being that the switched earth is shown normally OFF which is the behaviour I'm seeing, but the switched power is now reversed to normally ON and also goes to a brown/slate wire to the ABS module, neither of which are right for mine. My wiring colours match the 2006 diagram.

The ABS module can see the switching and gives the following readout:

Brake not pressed:


Brake pressed:


So the signals are getting to the module and are being interpreted. They seem to be backwards though?

Click image to enlarge

This says blue/red is the brake LAMP switch where purple/green is the brake switch. I would have thought that the switches should read the other way based on the normal ON/normal OFF behaviour of the switches?

This ABS module was replaced before I bought the car and I do have the old, apparently faulty one. Is it possible that the module changed its expected behaviour sometime in 2006 which might explain these readings and the fault? The numbers between the modules don't quite match up. I also have a module from an L320 I picked up just to see what codes would change (it isn't compatible).

New module installed before I bought car, didn't fix problem:

Click image to enlarge

Original module:

Click image to enlarge

Random module off an L320 from a wrecking yard:

Click image to enlarge

Original:
0 265 234 074 SRB 500 164
060521/1/0077

Current:
0 265 234 155 SRB 500 174
090902/6/1691

Random L320:
0 265 235 020 SRB 500 440
061212/1/1557

I'm guessing the second numbers are date/batch/serial numbers and not so important i.e. 060521 means 2006 May 21st which lines up with the build date for the car, and the other two can follow the same pattern.

Is the module in the car just incompatible????

Sorry for radio silence, I genuinely appreciate the feedback I'm getting and I'm just a bit slow between bouts of motivation at the moment. Feel free to remind me how much I'm going to enjoy this car once I can drive it!

I changed the abs module on my 2007 sc, no coding was required as I used the exact same part numbered module.

Afaiu you will need to code a different numbered module with an iid tool or similar.

Have you done that?

If you're able to determine the original module part number I'd try to get a replacement with the exact number.

Have you investigated the yaw sensor fault yet?

dingg1 wrote:

Have you done that?

I believe this was done by the previous owner's "Land Rover Specialist" workshop. The readouts from the Faultmate seem to suggest it's set up properly.

However...

I plugged in the original module today to see which codes changed, focussing on the brake circuit items.

Lo and behold, the P0504 and various "Brake switch circuit A/B correlation" codes are gone from all modules, including the Petrol EMS module which previously wouldn't clear it either. And most notably, the behaviour on the ABS module readout has changed to be more sensible:

Brake not pressed:


Brake pressed:


Compared with the currently installed module, the two brake switch readouts now say active/inactive together as one might intuitively expect.

I am now convinced that the ABS module in the car has a hardware or software incompatibility, and I'm almost convinced that the original module isn't faulty at all.

Here are the codes from the original module:


Yaw rate circuit codes still feature. This shot is from before I cleared the codes, they do all clear and not come back straight away but this seems significant.

Mikey wrote:

Have you investigated the yaw sensor fault yet?

This looks like the culprit now and I'm feeling motivated again. My current problem is that I can't find it in any wiring diagrams so far.

The yaw module has a 6 pin connector, I did buy a second hand yaw module a while ago but it didn't fix any problems. Module code is SRO000020, apparently common to L322s 2002-2009, L320 RRS 2005-2009 and LR3 2005-2009.

The late 2006 wiring diagram is the only one I have that references a yaw sensor at all and it has a 4 pin plug with completely different coloured wires to what I have:

I can see that there is a 4-pin yaw sensor SRO500140 apparently for 2007+ versions of these three vehicles.

Mine looks like this:

Click image to enlarge

It's a six pin as follows:
1 - Red
2 - Yellow/Brown
3 - Light Green
4 - Yellow/Black
5 - Yellow
6 - Blue

I've scoured the diagrams for this connector but I haven't come up with a match yet. I'll check the YB/YN tomorrow to see if they are high speed CANBUS wires, but I can't see any otherwise unaccounted for modules that should be on the bus on any diagrams.

I just need some idea of where these wires are meant to go so that I can test them for continuity now.

Well I'm stumped again.

The yaw sensor appears to be directly wired to the ABS module, having checked for continuity at every pin on the ABS connector. The pins match up like these:

Yaw Plug --- ABS Module
1 - Red --> Pin 18
2 - Yellow/Brown --> Pin 36
3 - Light Green --> Pin 28 (also 12v ign from Fuse 38 )
4 - Yellow/Black --> Pin 16
5 - Yellow --> Pin 20
6 - Blue --> Pin 15

The six pin direct wired to ABS module is similar to what I can find in diagrams for the earlier generation ABS module. I can't find this particular arrangement in any diagram that has the Bosch 5.7 unit, the 2006+ diagrams show a 4 pin module that communicates via a bus.

All of these wires have good continuity between sensor and ABS module and do not short to earth, 12V or each other. The YB/YN wires aren't a twisted pair and so aren't part of the CANBUS. Yaw codes are present across two yaw sensors and two ABS modules.

I'm pretty well defeated now.

If you have a yaw sensor fault, and the wiring checks out OK, why do you not suspect a yaw sensor failure?

Hi Mikey,

I've got the original yaw sensor and also a second hand one I picked up a while ago when I first read the codes. The fault codes are identical across both, similarly the live data readouts are identical no matter which one is plugged in and across two different ABS modules.

I can give an unsecured yaw sensor a little shake and the live values do change. The readouts don't make sense to me, the software says the car is yawing at 122 degrees/second when it's sitting still but also I don't completely trust the software readout to say the right thing. I only tackled the height sensors based on the software readouts saying one had nearly no signal volts and 5 amps current draw, when it turns out it was meant to read the other way around.

If one or both of the yaw sensors were faulty I would have thought there would be some difference in error codes or readouts between them.

I dont have a L322 so be gentle and certainly not a can bus expert
Have you seen this? or am I barking up the wrong tree?
https://www.fullfatrr.com/gallery/albums/userpics/23373/Yaw.pdf

It states the output voltage is variable dependant on vehicle conditions 0.5v to 4.5v for acceleration etc yaw is different, so can you not measure your voltage as an indicator. I would assume when at rest, you should see for example either 0.5v or 4.5v depending on whatever JLR used as their "at rest" value, anything above or below or in-between means its f ? 2018 SE SDV8 4.4 Byron Blue

btbtbtbt318 wrote:

Hi Mikey,

I've got the original yaw sensor and also a second hand one I picked up a while ago when I first read the codes. The fault codes are identical across both, similarly the live data readouts are identical no matter which one is plugged in and across two different ABS modules.

I can give an unsecured yaw sensor a little shake and the live values do change. The readouts don't make sense to me, the software says the car is yawing at 122 degrees/second when it's sitting still but also I don't completely trust the software readout to say the right thing. I only tackled the height sensors based on the software readouts saying one had nearly no signal volts and 5 amps current draw, when it turns out it was meant to read the other way around.

If one or both of the yaw sensors were faulty I would have thought there would be some difference in error codes or readouts between them.