DISCO4.COM - View topic - SUSPENSION PERFORMANCE STANDARDS AND DEFECTS

unclebob

Member Since: 06 Oct 2007
Location: Gloucestershire
Posts: 28

2005 Discovery 3 TDV6 SE Auto Zermatt Silver

simoniz wrote:
Bob

Regarding yr ride something simple to check - are you as in the D3 swinging freely???. Check under yr rear bumper on NS & OS and you will see what look like large rubber blocks,these should be swinging freely uninhibited. If these have become solid and unable to move then yr magic carpet ride on yr D3 will become very harsh. Its good practice to clean out any accumulated debris especially after any off roading ventures.

May not be the issue but worth a check.

:thumbsup:

Hi simonoz
Thanks for this. I had read about this on the forum so have had it cheked but no fault found and hence no improvement either but as you say -it was worth a try

28th Jan 2009 6:10 am

unclebob

Member Since: 06 Oct 2007
Location: Gloucestershire
Posts: 28

Re: SUSPENSION PERFORMANCE STANDARDS AND DEFECTS

ronp wrote:
unclebob wrote:

My first question is has anybody whose vehicle has had HDC type faults on start up replaced their battery and found the problem went away???

Yes.
:thumbsup:

sorry cann't help with the ride issue.

Hi ronp. Could you confirm if you had "normal" symptoms that would suggest your bettery was failing eg starting difficulties and what led you/dealer to conclude that a replacement battery would fix you HDC problem. Did the dealer do any tests before condeming the battery??? If so do you know what they were. I'm trying to make the link between failing battery and an HDC system failure warning but cant quit get it so any back ground knowledge you have on the link would be appreciated.

28th Jan 2009 6:19 am

unclebob

Member Since: 06 Oct 2007
Location: Gloucestershire
Posts: 28

wilsonmg wrote:
replaced battery... all sorted... :thumbsup:

Hi wilsonmg. Could you confirm if you had "normal" symptoms that would suggest your bettery was failing eg starting difficulties and what led you/dealer to conclude that a replacement battery would fix you HDC problem. Did the dealer do any tests before condeming the battery??? If so do you know what they were. I'm trying to make the link between failing battery and an HDC system failure warning but cant quit get it so any back ground knowledge you have on the link would be appreciated.

28th Jan 2009 6:23 am

unclebob

Member Since: 06 Oct 2007
Location: Gloucestershire
Posts: 28

Just for the record I thought you might be interested to know that my dealer has so far replaced all of the following components in trying to solve this problem.

brake light switch
failed brake light bulb
blue plug connector located beneath the nearside front wheel arch
Electronic Air Suspension (EAS) wiring harness
The automatic gear box Gear Selector Switch
Uploading the complete set of new software programmes for the whole car
Body Contol Module (main ECU)
Power Control Module
Right hand (off side) EGR valve

Most of this work was done in May/june 08. The suspension faults/poor ride (feels like it is in safe mode - although it will raise and lower) continued but perhaps significantly I didnt get an HDC warning light come on again untill Oct 08. Could this have been due to colder (relatively) nights. Is it significant that the original HDC problem started in Oct 2007 and lasted all through to may/june08. then didnt reappear untill Oct 08 and have persisted right through to date.

28th Jan 2009 6:47 am

phurley

Member Since: 19 Aug 2007
Location: So. NH
Posts: 175

For battery testing, the simplest is a voltmeter reading. Then for wet-cell batteries, measuring specific gravity with a hydrometer. Or for AGM, gel-cell, or sealed batteries, a load tester should be used.

As far as why an HDC fault on starting can be related to poor battery performance: in a car filled with software, often only the designers would be able to determine with certainty how that happens. However, given the circumstances, from a troubleshooting perspective, that's a good place to start. Weird or unusual fault conditions on start-up when the battery is at it's lowest charge state and the vehicle is idling (so the alternator's not generating a lot), and many vehicle systems are at near-max consumption (when the compressor is refilling the suspension reservoir!). Makes sense to me.

Of course, there are plenty of other possibilities for HDC failures, including all transmission failures, ABS system failures, etc. Sounds like your dealer has tried to be pretty thorough with those, though.

And there are plenty of weak battery symptoms that don't include HDC faults.

Are you familiar with the 'Butterfly Effect'...

28th Jan 2009 7:14 am

Blaserman

Member Since: 22 Sep 2008
Location: Either Pub or Work!
Posts: 225

2005 Discovery 3 TDV6 SE Manual Adriatic Blue

Unclebob
Do the HDC warnings still appear after the car has being running for five minutes?
With this I mean start it at the begining of your day, let it run for 5 mins turn it off and restart it?
I have a voltage issue with my battery as I have said due to short runs, I never have a problem with starting though.

"The fate of the wounded lies in the hands of the one who applys the first dressing"

Club MTR

Club Powerplant

28th Jan 2009 8:07 am

unclebob

Member Since: 06 Oct 2007
Location: Gloucestershire
Posts: 28

Blaserman wrote:
Unclebob
Do the HDC warnings still appear after the car has being running for five minutes?
With this I mean start it at the begining of your day, let it run for 5 mins turn it off and restart it?
I have a voltage issue with my battery as I have said due to short runs, I never have a problem with starting though. :thumbsup:

LIke you I never have problems with starting.
The answer to your question is no the HDC warnings do not appear after the car has being running for five minutes. The message will display on repeated cold starts but once the engine has warmed they stop displaying
To be clear the fault message actually onlys shows on the screen for less than 2 seconds and is gone and that is at the point of engaging the starter motor.

I religously wait for the system check and glow plug heater light to go out before turning the key to position III to fire up. It is only during the firing up that the HDC fault warning comes on. The suspension goes to safe mode. I then have to wait for the engine to warm up after which I turn off, reset using the 5 key turns and then restart to go on my way. The fault will not normally show again untill the next cold start.

The HDC failure warning has appeared consistantly every day since it was last at the dealers (about 8 weeks ago). If I dont bother to reset with the 5 key turns then the HDC fault doesnt display at all (but the suspension is in safe mode and hence a bit more rubbish to drive than normal) . Interestingly I can raise and lower the car when it is in the fault mode. I can also confirm that the HDC is in fact working dispite the error message to the contrary.

It was just last weekend that I read on the forum about battery problems having caused an HDC fault for others before which I have had no reason to suspect the battery as possibly faulty, as I mentioned earlier the car starts first time every time and the battery always seems to have plenty of grunt even at -18 degress which it was in Holland just a week or so ago.

However the forum reports got me thinking (always a bit risky these days) and I decide to try firing up the engine but not following through on the ignition to see if the starting load would trigger the fault to dispaly - which it did.

I then tried false starting with the engine hot and surprise surprise the fault did show. Having proved that the shock load of starting a warm engin caused HDC fault. Up until then I thought it was the cold temperature that caused the fault on starting because up to that point it had never displayed during a "normal" warm engine start . I am now left wondering if there is either a further component failure that we haven't yet found that causes a power spike or else a voltage drop during the start up due to perhaps the power drawn by the starter or a defect in the battery.

Given that this is the original battery and the problem first started in the early winter of 2007 I wonder if this has been the cause all along.

28th Jan 2009 8:59 am

Blaserman

Member Since: 22 Sep 2008
Location: Either Pub or Work!
Posts: 225

Quote:
The answer to your question is no the HDC warnings do not appear after the car has being running for five minutes

Sounds like the battery. As you say all functions seem to work normally. When you cycle through the computer using the 'i' key on the left hand stick, does it display any faults?
What do you mean by the suspension being in safe mode?

EDIT I also notice the LCD display is very slow to respond when the warnings are displayed. I put this down to the cold temprature too. "The fate of the wounded lies in the hands of the one who applys the first dressing"

Club MTR

Club Powerplant

28th Jan 2009 9:29 am

unclebob

Member Since: 06 Oct 2007
Location: Gloucestershire
Posts: 28

Unnecessary quote removed

Have checked the i key screen faily regularly and specifically after the HDC failures but there has never been a fault on the display.

The safe mode I mentioned is when the vehicle drops to the bump stops and the advisory message to restrict speed to 30mph or less comes on. The car drives like a shed in this mode. Sadley mine drives in a very similar way to safe mode all the time - it is a little better but not much. The safe mode warning message has only ever shown up once (the first time the HDC problem occurred back in Oct 07). This was said to have been due to a failed brake light bulb but after replacement the HDC fault still existed. LRA cleared the safemode warning and the car was fine to the next morning That was when the HDC failure warning came up again this time without the safe mode warning but with the safe mode ride characteristics. The brake light switch was replaced that day the car was fine till the next day and so it has gone one. I have had a whole raft of key components replaced as described earlier but all to no good so far)

28th Jan 2009 3:45 pm

phurley

Member Since: 19 Aug 2007
Location: So. NH
Posts: 175

Hi unclebob,
It might have been better if you had linked to your original post from last year http://www.disco3.co.uk/forum/topic17483.html - there's much more detailed history available.

Interestingly, I was composing a response for this thread about trailer wiring and whether you were towing in Europe at the time that I ran across your previous thread...

Firstly, I have to say that I'm really impressed with your dealer, Lancaster Reading. They have clearly been doing the right thing by you. Also, although I'm sure that LRA can be super-helpful, in your case, blithely clearing fault codes simply served to obfuscate the real problems. Sometimes, flat-bedding a vehicle is the better choice...

AFAICT you have had several distinct failures that were all related to the HDC function.
1. Brake light switch
2. Brake light bulb
3. CJB (central junction box - I think what you're referring to as the BCM) - has non-serviceable HDC relay
4. Chaffed & disconnected trailer wire (with attendent blown fuse)

As you have already discovered, the above failures were likely caused by the shorting trailer wires. Maybe some kind forum member could gallery the UK spec electrical diagram pages for "Stop and Reverse Lamps" & "Trailer socket", if you're interested? (Mine only covers NAS vehicles which have significant differences in that area.)

In addition, I believe you have also suffered from the following unrelated failures (which you've had repaired)
1. EGR - this is a common diesel failure. Many owners on this forum are bypassing them.
2. EAS connector water ingress at n/s/f wheel - this is/was a service bulletin LA-204-001 dated 2 May 05
3. I think the ECM replacement (what you referred to as PCM) was maybe due to technician error as it may have been their first time replacing a CJB. CJB stores the key transpoder codes for ECM start...
4. Some other EAS electrical failure - see note below.

So, I'm fairly certain that your previous problems were not caused by a bad battery. Now though, assuming you've had a good look over the trailer harness - especially where it passes near the harmonic damper - the battery seems a likely candidate.

Just to be thorough, what you haven't yet replaced on the HDC circuit (not much):
1. Trailer/rear wiper relay (assuming such a thing on UK spec vehicles)
2. Splice junction SJ814 - ties entire brake light system together (ABS, CJB, brake switch, lamps, trailer harness...)
3. Splice junction SJ813 - ties LH and high-mount stop lamps to SJ814
4. ABS module
5. Trailer harness
6. Trailer fuse block
7. Associated earthing points

Did you say you were on your way back to Lancaster Reading? If so, I'm sure they'll be able to figure this out.

Complete aside: unclear why the EAS harness was replaced (entire overlay harness?). Maybe harness chafing at n/s/f and n/s/r wheels - early builds did have exposed wiring in all the wrong places. See http://www.disco3.co.uk/forum/topic395.html and http://www.disco3.co.uk/forum/topic14591.html and http://www.disco3.co.uk/forum/topic28348-45.html.

29th Jan 2009 7:13 am

Jonty

Member Since: 13 Oct 2007
Location: On the beach
Posts: 417

2007 Discovery 3 4.4 V8 HSE Auto Java Black

Unclebob - re: ride quality - have you checked your tyre pressures aren't too high. My dealer once over-inflated the tyres and ride was much harder......

29th Jan 2009 2:27 pm

dubai

Member Since: 06 Jun 2007
Location: Dubai
Posts: 68

Re the ride quality. A simple check would be to have a test drive in another vehicle, either a car from the dealer or a forum member living not too far away from you.

30th Jan 2009 12:40 pm