I had some form of electrical failure on the way home from work yesterday in my 2003 V8 L322. Just driving along at around 50mph when I felt a small jolt (presumably the transmission selecting 4th gear for limp-home) followed by no response to the throttle pedal (engine was ticking over erratically, hunting up & down while I’m still coasting along at 40mph or so). I pulled over to the side of the road, turned the engine off, and when I tried to restart it I just got engine failsafe, transmission failsafe, HDC & air suspension faults all coming up on the message centre one after the other – oh, and the coolant gauge just went immediately to maximum. No response whatsoever when I tried to turn the starter.

Called out the AA. Their guy tried for nearly an hour to find the problem, including disconnecting the battery, using his power pack across the battery, etc. but couldn’t find any fault so they had to call for a recovery truck to get me home. Once home I tried to plug in my Faultmate but it said the battery voltage was too low to read the fault codes. I’ve taken the battery out to charge it (it’s around 3 years old) – though I guess the low voltage could possibly just be through it being sat there at the side of the road with the hazard lights flashing for over an hour?

My question is : could a battery failure be as instant as this and would it cause the symptoms I’ve described, where everything fails in a moment leaving you stranded? I had a replacement alternator fitted (by a LR dealership) less than a year ago and, when it failed, the battery light came on and I was able to drive to the dealers (approx. 20 minutes away) on what charge was left in the battery.

Any advice gratefully received!

Phil

from reading many posts here it seems that the fullfat is prone to the 'cascade' ecu failure where one ecu doesn't get enough power then that results in the next one failing and so on...
the battery and charging system would be my first test making sure everything is ok there, abs sensors have a nasty affect of causing hdc failure messages..
its a process of elimination Phil i'm afraid. ... - .- -.




Y. O. L. O.
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Sorry to be the bearer of bad news, but this does not sound like battery failure to me. Even if the battery goes south the alt should still be kicking out 14v and more than enough current to power most things running in the car. If the alt is knackered then you should have the charge light and reserve in the battery. so if both failed at the exact time it is possable but VERY unlikely to get those issues.

Also if that happened the ecu's would shut down and the engine would cut out compleatly, not run poorly.

The battery sounds past its best if it has drained significantly after only 1hour with the hazzards going. But that is not your biggest problem. But will be why the warning lights and hdc inactive ect are now shouwing.

As you have a faultmate your in a good position to find the problem quickly and deal with it. Keep on with what you where going to do (charge the batt put it back on and read the faults) i would clear the faults start it up and see how it runs and reread the faults as you will now have cleared a load of low voltage faults that could end up being a red herring.

Lets us know what you find.

When the engine is running you should in theory be able to disconnect the battery from the circuit and the alternator should keep everything going. The only way I can see your battery causing any fault when you are actually driving is if a cell went faulty and was pulling the voltage down from the alternator. I would be getting the battery tested first.  Previously..
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Thank you all for your advice.

Before replacing the battery I first checked the small grey fuse block in the E-box, where the engine and transmission ECUs live :

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Is the ebox the one under the bonnet with all the torx screws in? Glad it was a simple fix for you, I'd have NEVER found that! My Previous RR's!
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2001 4.6 HSE
2000 2.5 DHSE
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Good fix phil, lets hope its a permanent one and the blown fuse wasnt a symptom of something more serious. There is nothing that can't be fixed with a hammer😜😜
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It turns out that not only does Fuse 1 in the E-box power the engine and transmission ECUs

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Wauw Phil that is an interesting failure and you did well finding it so quickly. Glad to hear that you will soon be mobile again (you can probably drive like this anyway ??) also a good one for the Wiki (Stan, please ??) in case someone else gets this in the future. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

glad its sorted Phil.

Eugene/Phil , kinda struggling with a title for this one [before i put in the wiki.] ... - .- -.




Y. O. L. O.
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Heated Thermostat Connector Failure: could generate multiple seemingly unrelated electrical faults ??? MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

ebajema wrote:

... you did well finding it so quickly.

ebajema wrote:

(you can probably drive like this anyway ??)

This has been one of my gripes with all auto manufacturers (at least the ones who's cars I've worked on): the connectors are almost never available individually. AMP, one of the largest OEM connector suppliers has assortments available - but these generally start in the high 3 figure to low 4 figure range and even very large service shops can hardly justify a purchase such as this.

Thank goodness for Chinese copies.

Interesting problem, Phil. Did the guy on the other forum mention that this is a more common problem? 
RRC 2Dr, RRC 4Dr,
P38, and 2 L322s
(wife thinks I'm nuts - prob right, too)

Maybe find a local breaker and spend 30-40mins wire a pair of wire cutters cutting off loads of connectors before a vehicle is crushed?? FFRR MY06 facelift With TDV8 Alloys Zeros/ATR's
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SteveMFr wrote:

Interesting problem, Phil. Did the guy on the other forum mention that this is a more common problem?

He’s a technician at a Land Rover dealership in the US and I got the impression that he’s seen the (or a similar) problem before…..


I’m assuming that if I run for a while without the heated thermostat connected up (just as an experiment) that the engine coolant will operate at maximum temperature i.e. the engine ECU normally intervenes to lower the coolant temperature, by powering the thermostat heater, when higher engine performance/load is required. In the Manual it states that, in the event of the heated thermostat failing, the engine controller will “ensure the safe operation of the engine” so I’ll be interested to see what it does.

Phil

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