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Weird intermittent electrical faults
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rowlejohn
 


Member Since: 15 Sep 2017
Location: Montmorillon, Vienne (86)
Posts: 204

France 2008 Discovery 3 TDV6 HSE Auto Buckingham BlueDiscovery 3
Weird intermittent electrical faults

2008, Disco 3, TDV6,HSE, 192000 Miles

Hi folks
Have been having strange electrical faults intermittently appearing within 5 minutes of starting and driving the car during the past couple of months.
These are Parking Brake fault, satnav screen and radio/CD player go blank for about 10 seconds and occaisionally Special Programs fault with the special programs light going off. If the engine is switched off and restarted, the faults disappear and the car runs as normal.
Running diagnostics on the systems shows "No DTC's" present on the ECU's or applications.Both the HS & MS Canbus lines have been reset and cleared.
Last week, for the first time the heater blower motor speed started "Pulsing" and the "Battery" warning light came on and disappeared after a few minutes-this happened again today.
When I ran the diagnostics last weekend, I connected my multimeter to the battery and these are the results
Battery (Yuasa, 11 months old) All power off 12.6V
Alternator (Believe it's the original)-**See Comment**
Full Load 13.92-14.02V @ 2500 RPM
Idle Full load 13.96V
Idle No load 13.97V
**Comment**
About 30 seconds into the full load test the votage fluctuated breifly a couple of times between DC and AC. The battery warning light on the dash did not appear. I suspect the alternator could be causing the problems with the spurious faults.
These faults popped up again today when I was parked up with the engine running but for the first time the battery light came on and remained on for about 2 minutes before going out on it's own.
I have ordered a new Denso Alternator as I believe the one on the car is now 14 years old. That said, the battery still stars the car fine and I have not had the need to recharge it due to going flat.

Any guidance or further advice would be much appreciated Bow down
 Relocated to Mid France from N. Wales March 2021
Rovacomlite and IDD/ SSD diagnostics user
Previous Landies
3.9 SE Classic
3.5 V8 Disco
4.6 P38 HSE
L322 Vogue HSE
TD4 ES Freelander 1 
 
Post #230711510th Sep 2022 3:20 pm
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Pete K
 


Member Since: 15 Jan 2016
Location: GL
Posts: 10336

England 2005 Discovery 3 TDV6 HSE Auto Rimini RedDiscovery 3

Good shout ordering an alternator
  
Post #230711810th Sep 2022 3:49 pm
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rowlejohn
 


Member Since: 15 Sep 2017
Location: Montmorillon, Vienne (86)
Posts: 204

France 2008 Discovery 3 TDV6 HSE Auto Buckingham BlueDiscovery 3

Thanks for the response Pete Thumbs Up
Went out this evening and it was going crazy so alternator change it is. Fortunately have another smaller car for everyday use.
 Relocated to Mid France from N. Wales March 2021
Rovacomlite and IDD/ SSD diagnostics user
Previous Landies
3.9 SE Classic
3.5 V8 Disco
4.6 P38 HSE
L322 Vogue HSE
TD4 ES Freelander 1 
 
Post #230716410th Sep 2022 10:59 pm
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nigethecat
 


Member Since: 11 Sep 2016
Location: Marnoch
Posts: 4138

Ukraine 2016 Discovery 4 3.0 SDV6 Commercial XS Auto Corris GreyDiscovery 4

Check the voltage on your battery as well, you may think it’s fine as it starts the car but Discos are very sensitive to low voltage... you should be getting between 11-12 with the engine off and around 14 as soon as it starts..
 I want to see the sweets before I get into your windowless van... I'm not stupid!

Corris Grey D4 Commercial SE 2016
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Post #230716510th Sep 2022 11:10 pm
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rowlejohn
 


Member Since: 15 Sep 2017
Location: Montmorillon, Vienne (86)
Posts: 204

France 2008 Discovery 3 TDV6 HSE Auto Buckingham BlueDiscovery 3

Thanks for the reply Nige Thumbs Up

As can be seen from my post, I have 12.5V at the battery with everything switched off and between 13.96V at idle with full load and 13.98V at 2500RPM full load. The fact that it decides to briefly switch from DC to AC voltage output concerns me Shocked , especially given the complexity of LR systems.
Having owned a RR P38 for many years and their BECM problems, I'm quite conversant with them. The Disco thankfully is much improved and this is the first wierd experience with it. Given the mileage and the fact that the alternator has been on it for 14 years in my mind this seems the first thing to concentrate on....but maybe I'm wrong !!
 Relocated to Mid France from N. Wales March 2021
Rovacomlite and IDD/ SSD diagnostics user
Previous Landies
3.9 SE Classic
3.5 V8 Disco
4.6 P38 HSE
L322 Vogue HSE
TD4 ES Freelander 1 
 
Post #230717511th Sep 2022 8:09 am
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Shaunelectricon
 


Member Since: 13 Sep 2022
Location: Gloucestershire
Posts: 2

United Kingdom 2006 Discovery 3 TDV6 SE Auto Unknown ColourDiscovery 3

Had similar problems with ours disco3 turned out to be the alternator diode braking down alternators produce AC power and they need Rectifying back to DC with the diode pack within the alternator
  
Post #230761414th Sep 2022 12:07 pm
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rowlejohn
 


Member Since: 15 Sep 2017
Location: Montmorillon, Vienne (86)
Posts: 204

France 2008 Discovery 3 TDV6 HSE Auto Buckingham BlueDiscovery 3

Thanks for your reply Shaun Thumbs Up
That was my first thought a soon as I saw "AC Voltage" appear on the multimeter briefly. I am aware that DC controlled electronics do not like having a shot of AC.
I suppose 14 years and 190,000 odd miles from the originally fitted alternatot is pretty good in view of today's throwaway culture Cool so looking at the economics, £200/14 =£14 per year for a major electrical component is pretty good compared with the reliabilty and cost of othe LR cosumable components Rolling with laughter
 Relocated to Mid France from N. Wales March 2021
Rovacomlite and IDD/ SSD diagnostics user
Previous Landies
3.9 SE Classic
3.5 V8 Disco
4.6 P38 HSE
L322 Vogue HSE
TD4 ES Freelander 1 
 
Post #230767014th Sep 2022 8:41 pm
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rowlejohn
 


Member Since: 15 Sep 2017
Location: Montmorillon, Vienne (86)
Posts: 204

France 2008 Discovery 3 TDV6 HSE Auto Buckingham BlueDiscovery 3

Hi everyone....Update
During a recent short trip to the UK last week, picked up a new Hella Alternator from John Craddocks at half the price being quoted here in France where parts are a rip off.
Fitted this morning and all seems to be working as it should with 14.09 VDC being pumped into the battery on full load and no AC spikes !!
Ran a full fault code clearout together MS & HS canbus & canbus reset even though there were only a couple of historic DTC's that I have always had (Seat raise motor Hall sensor too many pulses) the seat works perfectly both manually and from memory function.

Thanks to all that posted comments on the topic Thumbs Up Thumbs Up Mr. Green Mr. Green
 Relocated to Mid France from N. Wales March 2021
Rovacomlite and IDD/ SSD diagnostics user
Previous Landies
3.9 SE Classic
3.5 V8 Disco
4.6 P38 HSE
L322 Vogue HSE
TD4 ES Freelander 1 
 
Post #23094472nd Oct 2022 12:38 pm
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