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Car won't start - electrical fault?


cheet22
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well,

after finally getting my A8 back 2 days before my holiday (new waterpump, cambelt etc) it was great. I then went away for 2 weeks for some sun, to come back to a car that wont fire.

Battery was flat as a pancake. Called AA out and he just spent an hour trying to get it to start.

He charged the battery (and jump started) but strange thing happens - car fires but wont run for more than a second.

Also, on the dash, the computer, fuel gauge and backlight illumination, mileage meter, clock - all are not working.

He checked his computer and it suggested water ingress to ECU area under bonnet. He checked this, and all fused throughout the car, with no luck.

He left scratching his head, me too. Suggests I try a hairdryer on the ECU tomorrow if it stops pissing down.

I just noticed when he left the rear passenger footwell is like an inch deep in water! - under front seat seems dry - as is roof etc - water looks to have come in through foot air duct - is that possible?

Anyone any ideas re the half working dash and non - starting before I again call a garage to pay them silly money......please help!!!!!

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Sounds to me like the usual imob problem. If the car runs then dies straight away then i would go for that. Have you tried another key ? If the car starts, dies then the immobilizer light blinks, then follow this

Immob issue

Ref the water in the footwell, well another well known issue, the drains need cleaning out by the sounds of it. If you have had LOTS of rain, then this is probably it, a pretty simple fix, and i would "think" thats its not linked to the starting issue

Drain cleaning

Ref the half working dash, well i have had similar symptoms when my battery went flat and tried to start the car, half was lit, half unlit, errors and allsorts. Once the battery was replaced, or fully charged, all was well again. You "may" find that a new or fully charged "good" battery will fix the starting issue to.

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ok,

now got car apart, and can see where immobiliser wire connects at "key" point of lock. Trouble is, the wire seems to go up to the bulkhead and disappears, so I can't see where it connects to - as per Audi Pages it should be visibil I think, but I see nothing.

Wonder if its changed - mines a 2000 3.7 Sport.

Anyone done this on a 2000 year car (facelift)?

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The problem is usually around the bit of black wire near the ignition barrel; remove the sleave and clean it together with the connector also add another heat shrink sleave to the black wire al the way to the coil reader. The yellow light doesn't always come on, though your dash lights haven't lit up after a new battery I don't think the two are related; hopefully.

Also just as a check find out what the resistance of the coil reader is, should be between 20 to 25 ohms

Hold up what part of dash doesn't light up? Not the service indicator and DIS is it?

forget that just read your firt post smashfreakB.gif

OK theirs something about the dash panel insert on the manual if when you've done the immobilser wire fix and you still have no joy go to the dreaded black box under the bonnet and do what the AA man essentaially said but also look at the connectors that are situated between the control modules- clean these properly with electirc contact cleaner; look for the white or green water residue marks and clean them dry out the entire box and then see what goes on. Plus if it is one of those connectors then some fault codes with VAGcom would be a tremedous help.

If water has shorted out something its those connectors first rather than the ECU which is higher up; I had water ingress in my ecu box but the connectors are what suffered and not the ECU, good luck and try to get hold of VAGcom.

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[ QUOTE ]

Also, on the dash, the computer, fuel gauge and backlight illumination, mileage meter, clock - all are not working.

[/ QUOTE ]

So what *is* working on the dash? The only things left are revs, temp and speedo, which are irrelevant as the car won't run... So is it all dead? Maybe, just maybe, for some reason your whole cluster is goosed (technical term... ah hem) and as the immobiliser partly lives in the cluster, perhaps that could be the cause.....

.. sadly I've got few answers though on how to prove / fix it. If you had Vagcom, you may be able to see that its not possible to connect to the instrument cluster any more, or at least it might have some error codes.....?

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Things that work:

ABS/ESP light comes on briefly as normal, battery light, handbrake light, rev counter appears to work (as the car starts for 1/2 seconds).

The clock, mileage, fuel gauge are not working for sure.

Temp, speedo of course can't tell until I can get it running.

So, if I understand you, you mean the immobiliser unit is in the dash, and thats where the other end of that wire goes from the key barrel? it does go upwards toward the back of the dash

Seems weird that the battery went flat at same time - don't suppose its possible that some memory needs erasing or anything is it?

I have an ebay VAG-COM cable but damned if I can get it to work. Don't suppose anyone around Glasgow has onw they would be willing to pop over to me for a couple quid? I'm in Robroyston, just 5 miles out of the city.

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[ QUOTE ]

So, if I understand you, you mean the immobiliser unit is in the dash, and thats where the other end of that wire goes from the key barrel? it does go upwards toward the back of the dash

[/ QUOTE ]

The immobiliser lives in both the instrument cluster, and the Engine ECU (in the big black box, top right hand side of the engine bay if you're stood with the bonnet up) It was a very secure design by Audi, but means its (a) tricky to diagnose and (b) expensive to replace if its all broken (which I fail to why it would be, unless water has managed to short everything out?....)

The keys are essentially coded into the immobiliser, and the instrument cluster and ECU are coded together too. Replacing either unit will completely immobilise the car as everything will need recoding. Recoding requires a login password to the immobiliser itself, for security reasons.

Best case, you have the white tags that came with your car keys, on a 99 year (i think you said 99?) they were still dishing out the 4 digit passwords on the key tags (under some scratchable foil), but they changed a year or so later to make it main dealer only with online passwords. If you dont have the tags, then definitely main dealer job, but they would want to fit a new dash.

With the white tags, you could in theory recode all the immobiliser stuff without Audi, should you need to replace the instrument cluster, but you would be stuck with the mileage of the donor dash, unless you buy a brand new one (£1K)

Its all a bit doom and gloom, and this is really, really worst case scenario. It just stuck me odd that so much of the dash was dead. Maybe thats a symptom of its other half - the ECU under the bonnet failing, but if the car will actually turn over and fire for a brief moment, sounds like the ECU is ok? Lets see if there is anyone local who can lend you a hand, otherwise it might be worth forking out an hour of Audi labour rate for them to diagnose for you... If you can tow it there..?

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Thanks for the help,

Its a 2000 year car.

Strange thing is, before I left it for 2 weeks it was perfect - all thats happened I know of for sure is we've had masses of rain over past 2 weeks here I'm told - like mega.

However, the black box area is totally dry, so I struggle to see how water can have shorted that - but I guess it could have dried out a bit since it went.

Think yer right, I need a diagnosis with VAG-COM to move ahead.

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Cheers Psyche - just tonight after 2 hours of messing, I finally think I got VAG Com to work!

Strangely too, tonight, I see many more lights on the dash (Immob light - which never goes off or flashes, seat belt light, transmission light, ABS and more) still no fuel gauge/rev counter/speedo tho!

And car still wont start

anyway, back to VAG Com, to be honest Im not sure what to do with it yet as its the first time it connected.

It has shown these Faults though in my initial playing:

Engine

17978 - Engine Start Blocked by Immobilizer

ABS Brakes

01203 - Electrical connection between ABS and Instrument Cluser 31-00 - Open or Short to Ground

Radio

00856 - Radio Antenna 36-00 - Open Circuit

I called the guy that replace my water pump just 2 weeks ago, and he reckons if battery been dead a week or more (as it could have been when I was away), the immob will need resetting - which he says he can do in a mo - but how do I do this (assuming I can with the shareware VAG com I have) or should I just get it to him to sort?

I need to get it towed, about 10/15 miles tho, hence if I can do this myself I would prefer!

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I'm no expert (haven't picked up my A8 from garage yet), but when I was viewing the car I've just bought, it had been sitting and the battery way dead (sitting 3 weeks or so). New battery in, and it fired up first time, so I don't know about this immobiliser resetting thing....

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You haven't cleaned those connectors have you yet? NONO3.GIF

Save the codes and try to clear them, but clean those connectors, the immobilser DTC is the one that pops up when you have the wire problem but because you have some dash probs and because the immobilser is connected into the dash panel I would look at the codes that are showing the open circuit I.E. clean those connectors in the black box. You dont need to reset the immobilser IMHO wink.gif If you got more lights then chances are it drying up sportifs2.gif

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Pull 'em apart 169144-ok.gif as the water gets inside and you get the green limescale type deposite over the connections - the ones that are colour coded you know green, black yellow etc(have pic at home will show later). Any water ingress no ,atter how small seems to come in throught the rear of that box rather than the front. Use some contact cleaner from maplins etc then dry the hell out of it, good luck

BTW did you do the immobilser wire fix?

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gonna do the wire fix tonight, although only the end that I can see at the key barrel - the other end disappears up behind the cluster - maybe on saturday I'll take out the cluster and see whats what.

with vag com BTW, when I tried to connect to Instruments, it could not connect to module - hope this is not a sign the cluster is buggered, and rather just down to it not connected properly at the black box.

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The part of the wire you need to clean & reinsulate is the portion you can see about 3-4inches starting from the Ignition barrel.

Vagcom may not communicate with the module for a number of reasons including dodgy 3rd paty interface, a problem with the K line etc.

It can only take up an evening of your time to do the immoby wire and clean the black box connectors. I had something similar happen to me (but still had dash lights on porperly) but the car wouldn't start proplerly (had already done the Immoby fix); it was these connectors that had moisture in them. I pulled them apart and clean them it fired up firts time after that 169144-ok.gif

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Cheers Ska,

I hear ya - I WILL do this asap - I just pray it all works, afetr spending £800 just two weeks ago, the other half gonna kill me if I need to spend more.

Whats even worse, I'm driving round in a damn Corsa just now, feel like a sardine in a tin!

Will let you know what happens asap - hopefully I'll get chance to look at it before weekend.

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Ok,

Removed all the multi plugs completely - and the ECU connectors, gave em agood clean with electric contact stuff and dried it all out.

Nothing looked even remotely tarnished/damp/wet

Anyways, still no life in dash (not even getting the extra lights I got yesterday now)

Tommorrow I do the immob - still struggle to see how that can disable the dash, but I guess it could get car to run to allow me to get it to garage

I might remove cluster too - looks easy enough - see if theres any dodgy connections for any reason

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OK,

Ive now cleaned the immob wire (not replaced) all the way up into the loom that it goes to - I took out the cluster too to let me do this.

No sign of any water etc near cluster

all back together - still same..... frown.gif

So, its still fires, runs for a second or two then dies. I still have no working cluster (apart from battery, ABS and handbrake lights)

Ive cleaned all connectors in black box, Ive replaced battery, Ive cleaned the immob wire and removed cluster to check for bad connection. Ive checked all fuses (100 times) and no further on.

Guess I'm fooked. My thought is to get the cluster rebuilt (http://www.bba-reman.com) ????

I still dont get what could have happened. 2 weeks away, and I get this and a flat battery - either the flat battery caused it, or was caused by it - whatever 'it' is!

Any other last suggestions? Anything I should do with VAG-COM to check/reset or anything?

I really dont want to take it to a dealer to have to pay for them to basically "guess" some solutions. However, I accept they might be able to find the fault where I cannot

advice?

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