Member Since: 14 Apr 2019
Location: Westbury
Posts: 2463
The main power feed comes from the battery, exits the battery box and follows what i would call the chassis leg on a normal car. If you look down under the power steering resiviour area you will see it loops down past this area and and around the actual chassis before going to the engine (its bolted to the sump under the oil pump) it then goes to the alternator then on to the starter.
I hope this makes sense, you need to check the area from where it loops around the body all the way to where its fixed to the engine. It runs in black conduit so you need to look and feel for any rub marks.
As far as the earth wires concerned you could run a jump lead from the negative terminal to a good earth point on the engine.
I prefer to run something like a 25mm2 cable bolted to the battery terminal and engine.
I would also check the factory earth wire, it bolts on the inner wing on the drivers side under the wheel arch linner then bolts to the chassis just in front of the suspension and finaly it bolts to the engine mount behind the alternator.
I have had a couple of cars that had strange faults that were caused by poor earthing.
A Golf GTD that put nemerous and random fault codes everytime it was started, i had a high resistance reading when testing continuity between the battery and engine. I removed and cleaned the factory earth wire and it made a slight improvement so i added an extra earth wire and it solved it.
I also had a Toyota Celica that misfired and showed a cam sensor fault when going up hills, i ran an extra cable and the fault stopped, when i checked the factory earth strap it fell apart in my handsAndrew
D3 2.7tdv6 2005
D4 3.0 SDV6 Commercial died and gone to LR heaven
D5 3.0 SDV6 HSE
13th Feb 2021 4:40 pm
TyphoonDisco
Member Since: 18 Jan 2021
Location: Morpeth
Posts: 102
I have tried to check the earthing points out. The earthing point that runs a short distance from the battery negative terminal to a bolt on the body looks good.
However, I can not for the life of me locate an earth bolted to the chassis from the alternator. From what I've read online there should be an earth lead bolted to the chassis in the drivers side front wheel arch area. I've had the bottom cover off the engine to try and locate the bottom of the alternator but I can't see an earth lead running off it and there's nothing attached to the chassis in either the NSF or OSF arch areas.
I've got some more info in case it helps diagnose the fault.
Shortly after I start the engine, whilst it is not that warm, the viscous fan runs faster than I would have expected. It's running at approx 1000rpm according to the GAP and it's pretty loud. I'd have thought it would only need to do that once the engine is at operating temperature.
In addition, I've been using the GAP to check out as many voltages in the system I can find.
When interrogating the TRANSFER CASE I have the following:
Control Module Supply Voltage = 13.9V
Sensor Supply Voltage A = 8.83V
Sensor Supply Voltage B = 10.0V
Transfer Box Motor Voltage = 0.0195V
Transfer Box Motor Positive Voltage = 0.243V
Differential Transfer Mode Select Module = 11.7V
Motor Output Shaft Speed Sensor Signal Voltage = 7.89V
Main engine control module voltage supply = N/A
Do they all look sensible? It's a bit strange that the Sensor Supply A and B differ.
13th Feb 2021 8:24 pm
TyphoonDisco
Member Since: 18 Jan 2021
Location: Morpeth
Posts: 102
Final plea for help!
Ok, I have to hold my hands up and admit defeat on this one. I've got it booked into my local indy this Friday for them to have a look.
Final plea for advice....
The multiple faults can come on with just the ignition on, with the engine running whilst stationary or with the car moving. It still only throws out multiple U0122 codes as previously described. It isn't throwing out anything that would point towards an actual fault. Turning the ignition off/on 3 times clears the dashboard faults.
One thing I have noticed is just before the failure happens the suspension tends to hunt slightly as if it's trying to level even though it's sat at normal height without issue. Plus I don't understand why it would still fail with the engine off/ignition on because the suspension shouldn't be running. I replaced the reservoir and the gallery pressure is holding fine, plus the fuse pulled test overnight showed no corners dropping.
When I'm driving the car, shortly before the fault I tend to get slightly random gear changes, really subtle.
Final thing, the most common time for it to happen whilst driving is just about to climb a hill or cresting a hill, which makes me again think it's related to something to do with levelling or suspension.
Is there anything in the car that outputs/inputs into the suspension system but also might affect transmission and could fail at standstill with ignition on?
16th Feb 2021 3:56 pm
TyphoonDisco
Member Since: 18 Jan 2021
Location: Morpeth
Posts: 102
I've now got a permanent U2005-31 (2F) fault code which reoccurs every time I clear it. What is random is the mileage is waaaayyyyyy out, the car has 100790 miles on it, not over 6 million!
NAVIGATION
U2005-31 (2F) Vehicle Speed - Frequency Modulation/Pulse width modulation failure - no signal
Triggered on 17-02-21 17:20:19
At 6453353 miles
Could this be what is setting off all the other troubles on the CANBUS or is it likely this is a result of the failures?
17th Feb 2021 6:27 pm
TyphoonDisco
Member Since: 18 Jan 2021
Location: Morpeth
Posts: 102
Ok, It's been into my independent LR garage today and they hooked the car up to their system. The chap seems to think all things are pointing towards the ABS module. When the failure happens he can't communicate with the ABS module until the ignition is recycled so he thinks the ABS module is playing up. What is strange is that the connectors all look perfect (he showed me) so it would have to be an issue inside. I thought they were sealed units but perhaps not.
The nightmare is the price tag attached to a new ABS module.
Wait for it...
£1800!
That's without the labour to fit it.
In addition, he advises that I change out the transfer case module at the same time since I described the slight oxidisation I'd seen inside it when I stripped it.
Total for parts will be £2100 and labour will be 3-4 hours.
Is it possible for me to do either/both of these jobs with a GAP IID BT? I know the transfer case module will require programming but I'm pretty sure this can be done with the IID once I pay for the coding from GAP.
Could I buy a used ABS module unit and fit that? Would it also require programming? Is it a case of having to bleed the entire brake system and refill?
Now that I suspect the ABS module I've been interrogating the various areas using the IID. I notice that the voltage fluctuates quite dramatically between 13.2-12.7v. It's the "CONTROL MODULE SUPPLY VOLTAGE B". Also, if I just monitor the status of each of the ABS inlet and outlet valves, they sometimes flicker from inactive to active then back to inactive even though the car is stationary with just the engine running.
Final point to note, the mileage when viewing TOTAL DISTANCE in the VDCM menu shows as 100814 but the actual vehicle mileage is 100835. I think something's gone adrift from the multiple instances of speedo failure when the car isn't clocking mileage.
If anyone can offer some help on the above I would be most grateful.
18th Feb 2021 5:56 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14177
Hiya
Ouch , Nothing like pulling ur hair out , know it’s can be very frustrating but stick with it as when I done all my suspension and airbag system faults it drove me nuts and ended up testing a lot of items along with getting invaluable help from here
Have u checked the live data of ur wheel speed sensors using the iid , also ur ABS sensors
Plus seen what the ohms are on ur canbus high and medium circuits , if ur unsure more than happy to help u on what pins to test at ur obd2 socket , battery leads have to be disconnected for this test
Know u can get ur instrument panel checked out, particularly as so many systems go through it,think it’s around £150 , know some of the members here can guide u on who to use, alas may be dead money spent so to speak but at least it gives u 100% confidence that it’s ok
Same with ur ABS module , if there’s a company to get it tested seeing there very expensive , alas could buy a second one but never know if it’s faulty or not , think u already mentioned you’ve done ur TCM , have u checked the ECM as well behind the TCM
Maybe test the ohms on ur can us before the fault and after to see what happens
Just an idea and have a chat with Pat at gap ref programming as he is extremely helpful
Last edited by gstuart on 19th Feb 2021 4:08 am. Edited 4 times in total
19th Feb 2021 3:28 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14177
Also found a pic of where that earth connection point is behind the drivers side wheel arch liner,
Plus the connectors for the are compressor etc I think after 2007 were moved to behind ur drivers side headlight , 3 x connector blocks , plus the other connectors on the rear passenger side wheel , have seen where some of the wires within the connectors have caused issues
Found some pics as well for u , alas u might have already checked them
Will of course like others help all we can for u to try and pin the error down
Hope this also helps
19th Feb 2021 3:48 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14177
Found a wider shot ref that earth point , for when I was doing my chassis treatment
Click image to enlarge
19th Feb 2021 3:51 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14177
Just remembered , there is also some earth points as u look at the engine down by the passenger side headlight , in front of the air filter tucked down attached to the slam panel
I couldnt trace all of them but I think they may come from the one that’s attached to the passenger side , behind the wheel arch liner and also maybe from the starter motor / alternator
Might be worth undoing them, cleaning them all up and reinstalling , plus can use a multimeter from them to ur battery earth post to ensure there all sound , I used a dremel to clean them
Sorry I’m rambling again, lol
Hope that helps
19th Feb 2021 3:56 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14177
Done some digging for u and see an ABS module , genuine bosch part is £780 , so don’t know where the garage got there prices from
Also wonder how many errors others from here have had issues with there ABS modules, plus assume u haven’t had an ABS error light come up on ur dashboard
Last edited by gstuart on 19th Feb 2021 6:18 am. Edited 1 time in total
19th Feb 2021 6:12 am
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 14177
Member Since: 18 Jan 2021
Location: Morpeth
Posts: 102
Stuart,
Thank you as always for taking the time to reply! I really appreciate it.
The speed sensors seem fine, before the fault occurs they all provide what looks to be almost identical data which only differs slightly due to what I think is the refresh rate. Of course, after the failure they all indicate N/A as the systems all let go.
I will check the ohms on the HSCAN and MSCAN and get back to you!
I've been in touch with Patrick, he is most helpful and I'm always impressed with just how quick he replies! I will be purchasing a TCM ECU flash from him once the new one arrives (ordered yesterday!)
I've checked the earths now and they seem fine visually and there's no movement. How can I test their effectiveness from the battery neutral? Excuse my lack of electrical knowledge.
Thanks for steers on the equipment. I picked up an OEM TCM from Devon 4x4 for £125.
I do have the ABS light on after the fault, along with loads of others for the transmission, suspension, park brake etc all being tripped off line.
What is really strange is when I interrogate the various sources of "TOTAL DISTANCE" using the GAP IID, they show slightly different mileages which I think has arisen due to the failure of the speedo when this fault happens because the odometer stops counting up. Also, something v strange is happening in the reported "TOTAL MILEAGE" on the U2005-31 (2F.) code because the mileage is now up in the 8 million region!!!
19th Feb 2021 9:43 am
aja4x4
Member Since: 14 Apr 2019
Location: Westbury
Posts: 2463
Testing the earth wires is easy enough with a multimeter set to continuity.
Test between the negative battery terminal and a number of place on the engine that are clean and connect to the engine block like the oil cooler boltsAndrew
D3 2.7tdv6 2005
D4 3.0 SDV6 Commercial died and gone to LR heaven
D5 3.0 SDV6 HSE
19th Feb 2021 11:09 am
TyphoonDisco
Member Since: 18 Jan 2021
Location: Morpeth
Posts: 102
Okay,
I'm not sure what to read into this but here we go...
Resistance between 3/11 - 62.2 Ohms
Resistance between 6/14 - 60.2 Ohms
I then reconnected the battery, started the engine and waited for the fault to occur. I was waiting aaagggggees which is sods law. Once the fault occurred it kicked off all the usual systems, suspension lowered etc. I disconnected the battery and tested the resistance again and it was exactly the same as above. I wonder if this is because the fault is transitory and doesn't leave either BUS out of action?
Furthermore, I now have a regular fault code which reoccurs after clearing which is a development from the very start of my issues. It is:
Navigation
MOST
U2005-31 (2F.) Vehicle Speed - Frequency Modulation/Pulse Width Modulation Failure - No Signal
Triggered on 19-02-2021 11:55:20
At 8000796 mi
The mileage is very strange. Over 8 million miles! I did note this a while ago and it was on 6 million odd so it is moving upwards but at an astonishing rate.
Also related to the mileage, the instrument panel shows 100835 but all of the other systems state 100814 so there's a discrepancy in the system somewhere.
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I will be purchasing a TCM ECU flash from him once the new one arrives (ordered yesterday!)
