Comms errors are just that, if one ECU does not hand shake to the next in the loop then it will throw up these comms error's on all the ECU's down stream of the failed ECU in the MOST loop.
The P codes are a starting point, but you really need the prefix code number at the end of the P codes to drill down where the fault is.
Thats why a lot of cheap scanners are ok to show you a fault, but that might not be the problem..
Flack
1st Feb 2021 11:09 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13657
@flack
As always thank u so much
Would be awesome if there was a way to know what direction the canbus went so that u could go to the last ecu in the canbus series that flagged the errors forward of it so u could then start there , hope that sort of makes sense
But of course understand where ur coming from of how complicated the canbus can be and how important it is to have the most complete error codes
Know when my airbag system had issues it flagged up a multitude of fault codes along side
As always thanks again
1st Feb 2021 3:49 pm
TyphoonDisco
Member Since: 19 Jan 2021
Location: Morpeth
Posts: 102
So, I have now:
- Fitted a new air suspension reservoir
- Fitted a new air line between the reservoir and the reservoir block valve (previous one split)
- Tightened and leak checked all of the lines to/from the reservoir block valve
- Done multiple fuse-out drop checks of the suspension and have zero movement front and rear
The suspension seems to be behaving now with no major issues.
In addition, I have fitted a brand new Exide Premium battery.
However, I am STILL getting the multiple U0122 fault codes.
The codes will occur whether moving or stationary and the only common denominator is that they occur when the car is warm. By warm, I mean the temperature of the engine is up to 90 degrees celsius.
I fear I am now chasing an electrical fault. I've read elsewhere on this forum that there are some connectors that, once they heat up, can expand and fail to make a proper contact which results in a failure across the CANBUS.
Are there any known culprits I should begin with?
Thank you.
8th Feb 2021 12:40 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13657
Hi
Great ur getting somewhere
Hope u don’t mind me asking but did u charge the battery up before fitting , always best to do so before hand so u know it’s fully charged . would also recheck to ensure what the Vdc is with the engine off and running
Would also do a hard reset
Normally the U codes can just be ignored unless of course there’s issues
One last thing I would be tempted to check ur earth leads, try fitting a jump lead from the engine lifting bracket to ur battery earth post to see if that makes any difference
Hopefully someone else will be along to also help u
Hope that helps a little and plse let us know how u get on as there are further tests u can do on the canbus etc
8th Feb 2021 2:10 pm
TyphoonDisco
Member Since: 19 Jan 2021
Location: Morpeth
Posts: 102
Hi Stuart,
I did not charge the battery before fitting but can tell you that it is pushing out the following voltage cold (v cold at the moment!)
- GAP tool = 12.2v
- Fluke meter on battery terminals = 12.34v
- GAP tool with engine running = 14.0v
- Fluke meter with engine running = 14.08v
I would love to ignore the U codes but every time they occur I get the usual gambit of warnings, the suspension drops to access, the special programmes disappear, the speedo doesn't work etc.
What did you mean by a hard reset? Is this just clearing the codes using the GAP? I do this each time.
I will check the battery earth post as recommended. Is this the lead running from the battery positive cable? It looks to be a shared terminal.
Thanks very much once again!
8th Feb 2021 2:54 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13657
Hiya
Ur so welcome and always a pleasure to help where possible
Ah sorry indeed battery needs a good charge as need a min of 12.6Vdc standing , think mine runs around 14.4Vdc with engine running
Ref hard reset that’s where u remove both battery leads from the battery and touch the leads together making sure not to touch the battery , might need a jump cable between them if there too short , leaving them touched for a few minutes, then remove jump lead and connecting earth and positive back onto ur battery , can be done after u have charged and disconnected ur battery charger
Ctek charger can easily be connected via ur 12s towing socket if one is fitted without having to lift ur bonnet
U can use ur multimeter as well to ensure the earth on the engine lifting mount to ur battery terminal is a good earth , the mount as u look at the engine is on the rh side near the front
Ur earth terminal should be at the back of the battery , the front ones are ur positives so need to ensure that u stay away from them, so just use a jump lead from the back battery earth post to the engine lifting bracket
Ah i see ref errors as interesting they only appear when at temperature, wonder if a sensor is causing the issue , know the TCM module behind the battery can sometimes get water in the pins
Know the gap iid will shut down if the battery voltage gets to low ,
Have u got a ctek battery charger plse as would put that on over night , do a hard reset and then try it again as we can then work our way through the errors step by step and ensure then we know 100% what we’ve done
We may need to check live data cold and then hot to see what’s changing , ie maybe a sensor is going out of range when it gets hot and throwing the errors
Hope that helps
Ps, meant to say the front positive battery leads, one runs to ur fuse box the other to the alternator
Last edited by gstuart on 8th Feb 2021 5:03 pm. Edited 1 time in total
8th Feb 2021 4:44 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13657
So just found some pics, that engine lifting bracket is under the plastic cover with the 3 x holes , but once the battery is charged and hard reset is done can see if we need to start delving further
Plus indeed mine runs around 14.3Vdc with the engine running , I installed some gauges , ignore the panel fitted right hand side one as I’ve got dual battery’s, middle one shows the cabin temperature, also had a plug in volt meter as was comparing it , the plug in ones are very cheap and gives u a constant display whilst driving so can see the voltage output is , LH gauge is my main battery Vdc
Hope that helps
Ps, can u do me a favour as well , can u check ur rear lights and brake lights plse , just wish to rule that out, thks
Click image to enlarge
8th Feb 2021 4:58 pm
TyphoonDisco
Member Since: 19 Jan 2021
Location: Morpeth
Posts: 102
Well, I don't want to tempt fate but I've just been to Tesco and back (35 mins each way) and there were no warnings! The battery was showing 14.2v whilst driving so I wonder if the new battery is being charged sufficiently and it has done the trick!
I'm not holding my breath but it certainly looks positive!
I will invest in one of those chargers because I do have the towing electrics fitted.
I'm going to give the car another few long runs and if all is well I will report back to wrap up this thread.
ps. All lights are fine. I have replaced all of the rear bulbs with brand new 380/382s (manufacturer is Ring - I got the 3x longer life ones from Halfords). I am trying to source bulbs which use a straight filament instead of the coil as they tend to hold up better in bumpy conditions. I am happy to take advice on the best bulbs though.
8th Feb 2021 9:19 pm
TyphoonDisco
Member Since: 19 Jan 2021
Location: Morpeth
Posts: 102
It looks like I spoke too soon!
Car has behaved for a couple of journeys and then when returning home on a 40 minute journey last night I got the same failure! Full list of warnings on the dash, suspension lowered, no ABS, no speedo etc etc.
So it's not the brake switch, bulbs, suspension or battery.
As I'm getting the feel of the car I think I can offer a bit more in the way of symptoms. The warning only ever occurs when the car is operating at full temperature. ie. The engine is up to circa 90 degrees.
It is not linked to a brake pedal push or any switch selections in cockpit.
Once the car is up to temperature the failure can occur whilst moving or with the car stationary and engine running.
A few points to note about yesterday's journey.
- My outbound journey showed the battery voltage on the GAP as 14.4v whilst driving.
- My inbound journey (when the fault occurred) showed the voltage as 13.9v whilst driving.
Should I be reading anything into this?
Also, I can't help but think that the auto gearbox starts to get a little unpredictable in the minutes leading up to the failure. Nothing massive, just the odd gear shift that I wouldn't be expecting. It's almost imperceivable. Not sure this would explain why the fault occurs at standstill either.
Finally, here's the list of codes. It's the same U0122 CANBUS errors but note that the TRANSFER CASE and PARKING BRAKE are consistently the first 2 errors each time.
Member Since: 19 Jan 2021
Location: Morpeth
Posts: 102
ps. Is it possible for me to change the original thread title to something more apt?
11th Feb 2021 11:39 am
TyphoonDisco
Member Since: 19 Jan 2021
Location: Morpeth
Posts: 102
I had the car on a charger all evening and went out this morning and fired her up.
I noted that immediately after start, the GAP voltage showed approx 12.7Vdc. I expected this to be higher. After a short while of running at idle, and with a couple of minor blips of the accelerator it settled at 13.7Vdc and then eventually rose to 14.0-14.2Vdc.
What I did notice is that whilst idling, the engine note would often change for a brief moment with a reduction in voltage which then recovered immediately. It did this for a while until the engine was warmed up at which stage it settled down to a steady 14.2Vdc. It was like the battery was not being charged for a very brief moment. Could this be an alternator issue?
I hopped in for a drive and after about 200m, just as the car kicked down a gear to go up an incline, DING DONG, all the same warnings/failures. I'm having no luck whatsoever tracing this fault!
My next steps are going to be a new transfer module and a new alternator so I can discount those as potential issues.
Does anyone else have any ideas????
Codes from today are below. Note the TRANSFER CASE and PARKING BRAKE are the first 2 cuplrits again!
Vehicle scanned on 13-02-2021 13:17
Using IIDTool BT V4.0 B2691
Airbag
U0122-87 (2C) Lost communication with vehicle dynamics control module - Bus signal/message failure - missing a message
( on 13-02-2021 13:15:20 at 100773 mi )
Navigation
U2005-31 (6C) Vehicle speed - Frequency modulation/pulse width modulation failure - no signal
( on 13-02-2021 13:15:46 at 5394577 mi )
Parking Brake
U0122-87 (B8) Lost communication with vehicle dynamics control module - Bus signal/message failure - missing a message
( on 13-02-2021 13:15:18 at 100773 mi )
Steering Angle
U0122-87 (68) Lost communication with vehicle dynamics control module - Bus signal/message failure - missing a message
( on 13-02-2021 13:15:22 at 100773 mi )
Suspension
U0122-87 (2E) Lost communication with vehicle dynamics control module - Bus signal/message failure - missing a message
( on 13-02-2021 13:15:19 at 100773 mi )
Terrain Response
U0122-87 (28) Lost communication with vehicle dynamics control module - Bus signal/message failure - missing a message
( on 13-02-2021 13:15:19 at 100773 mi )
Transfer Case
U0122-87 (28) Lost communication with vehicle dynamics control module - Bus signal/message failure - missing a message
( on 13-02-2021 13:15:18 at 100773 mi )
13th Feb 2021 3:39 pm
aja4x4
Member Since: 14 Apr 2019
Location: Westbury
Posts: 2459
They are only imformation codes but the fact they all happened at the same time may indicate something like a bad connection.
Have you checked your battery terminals? Halfords fitted a new battery just before i purchased my car and while investigating some issues i went to remove the battery and found the negative terminal could just be lifted off even though
The securing nut was done up tight.
I loosened the clamp and pushed it down over the terminal and it tightened up as it should do, this sorted out my intermitent problems.Andrew
D3 2.7tdv6 2005
D4 3.0 SDV6 Commercial died and gone to LR heaven
D5 3.0 SDV6 HSE
13th Feb 2021 4:06 pm
TyphoonDisco
Member Since: 19 Jan 2021
Location: Morpeth
Posts: 102
Yep, battery is all good including connections. If you have a look through the entire thread you'll get a good idea about the circumstances in which the fault occurs.
Thanks for the reply.
13th Feb 2021 4:38 pm
aja4x4
Member Since: 14 Apr 2019
Location: Westbury
Posts: 2459
Its strange its when going up hill
I would agree with you about changing the alternator and i would check the main power feed from the battery that runs down under the engine, it can rub on the chassis leg under the FBH.
It wouldnt hurt to run an extra earth strap to the engine.Andrew
D3 2.7tdv6 2005
D4 3.0 SDV6 Commercial died and gone to LR heaven
D5 3.0 SDV6 HSE
13th Feb 2021 5:01 pm
TyphoonDisco
Member Since: 19 Jan 2021
Location: Morpeth
Posts: 102
Thanks Andrew. Can you please give me a little more info on how to check the main power feed and where the rub might be.
Do you have a recommendation on how to fit an extra earth strap?
I see you concur with the requirement for a new alternator. Do you think the little blips of lower voltage are related to a poor alternator?
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