Major ongoing problems with electrics

Back in January I posted in this thread https://www.landyzone.co.uk/land-ro...-connectors-water-damage.356064/#post-4776997 about a problem we had which has seen the vehicle off the road since November last year.

The symptoms are the vehicle will run for a few days and then randomly go through a 'cascade' failure with dozens of error codes, engine into the limp home mode and then when you turn it off, nothing works.. can't even open the boot at that point. On one occasion the car was also left in gear and you couldn't put it back into neutral. Plugging in the computer just shows dozens of errors and its impossible to see what started it.

The original line of thinking was that the problem was caused by water having corroded the wiring loom headers in the DS footwell (presumably resulting in voltage drop because of resistance that the bus then detects as an error, shutting things down).

After weeks of trying to clean up contacts, we followed the advice here, cutting and soldering all of the connections across 4 sets of headers. That seemed to solve it for a week before the same problem was back

We then traced back further to a set of headers under the rear seats with some indication that perhaps those were also oxidized. Again cutting and soldering those seemed to fix it for a week before failing again (right at the beginning of lockdown!)

At this point, we are out of ideas. I'm certain that all of the connections are good, they were professionally spliced using the neat little solder-crimp-heat-shrink connectors. Everything tests correctly.

I'm beginning to wonder now whether the fault is actually with one of the modules - ECU maybe? But I have no idea where to start with it. Any help or pointers would be hugely appreciated... at this point I have a large piece of scrap

If you have ruled all connectors, battery condition battery connectors, along with earth straps/wires to and from battery/chassis and battery/engine.
It logically leaves Ecu's. Have you had any issues with the battery being connected the wrong way, this can fry Ecu's and cause glitches.
It sounds like a good plan you've got going through it the way you are.
Canbus errors are a bloody nightmare... If you sort this you can fix my volvo v50 that suffers this once a year

If the water has effected the wiring is even more likely to effect the ecus if it’s been long term.
one guy moved all his ecus under the seats to over head.

Have you managed stop the water coming in? no point replacing if itl go same.

Yes, water was blocked channel and that was solved from the get go. My question is - if it is a control module, then where do I start. I used the term 'ECU' in a failr generic way - I was told that it could in fact be any one of dizens of individual modules that could be the problem? As far as the actual ECU - how would you go about diagnosing that? Presumably, I could get an ECU from a breaker and have it reprogramed? I don't suppose that a main dealer would have diagnostics kit that wasn't available to independents that might be able to track it down?

https://www.landyzone.co.uk/land-rover/diagnostic-system-failures-confused.256950/have a read through this thread, is there any thing you can find that helps?
There are companies that test Ecu's but as you say where to start is a good question. As you get a complete shut down, maybe the main ecu or BECM...
In fact I'll tag a wizard. @Saint.V8

Thanks for the pointer. The way it fails it to first report traction control, then gearbox, then it cycles through everything within a matter of 20 seconds. I haven't been able to see a pattern to it and when you plug the computer in the list doesn't seem to always have the same order. The only way to restart the car is to clear all of the faults one by one. It is a 2011 L322 which I don't think has a BECM?

benstone said:

Thanks for the pointer. The way it fails it to first report traction control, then gearbox, then it cycles through everything within a matter of 20 seconds. I haven't been able to see a pattern to it and when you plug the computer in the list doesn't seem to always have the same order. The only way to restart the car is to clear all of the faults one by one. It is a 2011 L322 which I don't think has a BECM?

Click to expand...

Not a BECM but I think it has a BCM.

OK so I'll wait to see what others say but it sounds like pulling one or more and sending them to someone who can test and diagnose them might be the next step. Other than the main engine ECU and the BCM is there anything else it could be I wonder.

Can’t hurt to check your earth straps if you can get to them, battery condition. Won’t cost

benstone said:

OK so I'll wait to see what others say but it sounds like pulling one or more and sending them to someone who can test and diagnose them might be the next step. Other than the main engine ECU and the BCM is there anything else it could be I wonder.

Click to expand...

I don't know much, but potentially it could be any module on the CAN BUS

Yeah, that is what I fear. It could be almost any module It's not even the cost at this stage. The vehicle has been worked on by of my great mates for the past few months. He owns a big independent dealership with a dozen bays and 2 full-time electrical techs who I know personally well. They have been doing this as a huge favor to me and god knows how many hours we have now spent on it. Battery (is new) and earthing is something that we ruled out day one though now you have got me thinking about it, this whole thing started shortly after it had been in with an alternator failure .. I wonder now whether that is what kicked it all off. Presumably, you can't just disconnect modules to see if you can eliminate it that way?

If you have the facility to erase codes you can pull what you like. Try the steering angle sensor plug first...

OK sounds like you know something about it I guess we could just start pulling them, clearing the codes, and then seeing if the remaining ones trip it... It will be a bugger if there is more than one faulty module! Why the steering angle sensor out of interest?

Mark Piercy said:

https://www.landyzone.co.uk/land-rover/diagnostic-system-failures-confused.256950/have a read through this thread, is there any thing you can find that helps?
There are companies that test Ecu's but as you say where to start is a good question. As you get a complete shut down, maybe the main ecu or BECM...
In fact I'll tag a wizard. @Saint.V8

Click to expand...

The link I added has all kinds of funny electronic madness going on down to one thing. I know it's a long shot but maybe and just maybe....
If not then you can rule it out at least

Got it.. I'll get them to check that as soon as normal operations resume Thank for your help everyone.

Your more than welcome, good luck.

2011 is a bit beyond my ken, but if it has a CANbus of twisted pairs, then I attach a document about tracing faults on the CAN....admittedly t is BMW biased, and woudl be more help on a 2002-2005 model, but it gives information on how the CAN works, what can drag it down, and how to use a scope to check for errors.

Best of luck. If all the wiring is good, connectiosn are good then it can only be an ECU/Module dragging the bus down. There is a ga-zillion miles of wiring and in the later models - fibre optics - to check!

Does this translate to a "f*cking nightmare" scenario

Forgot to add the attachment......it is now below!

Seem to recall a thread where a failing steering angle sensor was cocking up the CANBUS. Might be worth unplugging that?