Car wont start, dash lights fading.

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TwinCamMan

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I have a pre facelift 2000 Audi S3, that has just developed a starting problem. I've had no problems with the car over the last year until now. Two days ago it became I found that it did not start on the first turn of the key and put this down to not being driven in the previous three weeks. I drove it for 10 minutes or so and parked up, 20 minutes later the car took 5 minutes to start. The following day the same problem but over 5 minutes to start. The battery seems strong when it goes to turn the car over and even replaced the battery as thought it may be dodgy but still the same problem. The dash lights are faint (air bag, battery, hand brake) and dim on and off every three seconds while the ignition is turned on, while the clock and odometer are remaining bright. The DIS lights up properly but takes 3 or 4 seconds to do so unlike before. The only problem I've had with the car is the rear brake lights have stopped working (probably brake switch) and got an error for this on my DIS. Which is the reason I haven't driven it in three weeks. I tried running the VagCom but it seems that it cant communicate properly with the car with this problem.

Any help would be greatly appreciated.
 
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Sounds like a short of somekind... If your battery and alternator have tested fine. I would personally try pulling some fuses, like lights to see if it makes any difference. Sounds like it could be a little more complex though
 
sounds like an earthing problem, check your body's earth point that you know of for any corrosion, etc
 
Went out to take a look at a few fuses and the problem has grown. Now with the ignition on the lights are even more faded, the DIS, clock and odometer is turning on and off and after 15 seconds or so the immobilser light starts flickering as if the battery is dead. The radio and air-con is now dead. But turn the key and it cranks good and strong. VagCom still not communicating.....
 
Earthing problems can manifest them in strange ways, it's definitely worth checking the grounding points for any corrosion etc. I know there's the main one under the battery but not sure where the others are...

Hope you get this sorted mate.
 
Ok cleaned the 3 grounding point under the battery, which weren't too bad, and unfortunately still no better. Then went pulling fuses one by one, no difference until I came to fuse 7, which is for the reversing lights. When I remove it the dash lights up, not to the same intensity as it used to but not far from it, but the car still wont start. Any thoughts?
 
End result was I put the car in the garage for the last 6 months and drove my other car. Went at it again today, 6 months on, and still the same problem. Anyone have any ideas as I really want to get back to driving my S3.
 
- Sorry to hear you still havent solved the issue, as above really there must be some kind of short or grounding issue. you say youve checked the one the battery have you checked the others ?.. ( i.e engine to chassis )

- someone mentioned changing the relay No. 30 after having troubles with starting, long shot but might be worth a try.

- does it fire at all when you spend ages cranking it to try and get it started ? if so could be fuel starvation ? try giving it a good service, new fuel filter , plugs etc.

- As far as the lights being dim are they initially bright even if for a split second before you start cranking ?? . Cranking will draw a massive amount of current from the battery and even after a ten minute run your battery could still do with a good amount more charge in it. If you can get it started i would suggest giving it a good half hour of running to boost the battery back up, if not stick a trickle charger on it.

Ps. i know you said it turns over ok so you may not see this idea/s working but its worth a try to rule out a few things.
( Your battery may be low but have enough to crank over the engine / not enough to multitask ( I.e handle all the lighting too).

Hope this helps as theres not many other suggestions coming in for you bud. This is a bit of a puzzler :S.

Jon.
 
* apologies as youve changed the battery for a new one.

- If the new one made no odds then there must be a short ( Constant drain on the battery, check you glovebox light switches off ok when its meant to).

- As mentioned before check all earthing as even witha new battery a dodgey earth would stop you from getting the batterys full potential. ( It wouldnt charge correctly etc...)

Jon
 
Thanks for your feedback Jon.

- checked the grounding points under the battery, and then to check the earth to the engine and gearbox, I used a jump lead connected to the relevant area and connected it directly to the battery all to no avail.

- relay no 30, is this the fuel pump relay?

- car now will not start at all, it will crank away for you but will not fire. initially when this happened first I was at my sisters house and I got it started after four attempts, i did this by removing the key from the ignition and putting it back in again (four times). when the car started, it did like it always used to and it ran fine on the drive home. there was no lack of power, no missing, no hesitation. When I got home turned it off and it wouldn't start again. the following day it started for me, but only after putting the key in and out about twenty times, and again started fine and drove perfectly. the next time after that about seventy times, and it hasn't started since.

- it's the dash lights that I'm on about being dim. And now they remain dim, they aren't even bright for a moment. they obviously get dimmer when I go to crank the car.

To ensure the voltage remains strong on the car I can always connect my other car to it with a set of jump leads to keep the voltage up.
 
Check the earth strap to the gearbox, I ended up moving mine after having problems to the very top of the gearbox.
 
Could possibly be the ignition barrel has failed, mine did but the car wouldnt even crank when this happened but we could still bump start it, If you can bump start it then this might be your problem.
 
- MMM i see , have you got a spare key for it ??.. im just having random thoughts now.. if you can, try the other key to check the immobiliser or something isnt playing up.

- but yh with regards to relay No. 30 i believe its fuel pump related as you say, maybe it is on its way out and as a result its struggling to get fuel ??..

Ill keep thinking buddy ,

Jon.
 
Ignition switch itself would be my guess. Unclip it from the back of the barrel and see if there is any slack etc or if moving any dirction fixes it
 
I left the car on trickle charge last night and when I went to it this morning and put the key in the ignition the light on the dash didn't dim like they had been doing. When I turned the key, it fired for about half a second and then died. If I tried it with my foot to the floor it would instantly tried to rev towards 3000rpm and immediately died. With no throttle it would hit just over 1000 rpm and then died. I tried a few more things but within 15 minutes I was back to where I started. With the car not firing up (for the split second) and the dash lights fading.

Jacko, - I used a jump lead to connect the earth terminal of the battery to the engine and the gearbox, but no joy. So the earth to the gearbox isn't the problem.

Chopper, - the car always cranks but unfortunately won't do much more than that.

Jon, - I tried both keys today, and it's the exact same with both of them.

- I then checked the relay for the fuel pump, but this is where it gets interesting. The relay works if you manually activate it, (i.e. cover off) but not if you go through the motions normally. And the 12v power supply (blue wire) which is the signal to the relay is reading 0v. This is when I noticed that the fuel pump doesn't prime when I open the drivers door or when I put the key in the ignition.

Does anyone have any ideas if there is another relay that sends a signal to the fuel pump relay?

Mark, - you also mention the ignition switch, if this was the problem would it even crank? I'll give it a go anyway, I've nothing to loose, but I wait for the daylight, so a job for the morning.

Thanks for all your help and suggestions, and keep them coming, all are appreciated.

Darragh.
 
The switches fail sometimes not giving constant power. It sounds like your dash isn't getting the power it needs as the immo is cutting in.

X relay can also cause it, it might be worth dropping the drivers knee bolster and looking at the conectors under there also
 
Ahh very interesting chap, sounds like you might be getting somewhere slowly with the fact after trickle charging it things seemed better and that the fuel pump isnt priming etc (which could be that relay or the supply).

- so to clarify What happens when you turn the ignition on ( key to second position ) you say you cant hear the buzzing of the fuel priming ?

- Its a long shot but it does sound like its struggling because of fuel starvation, for one reason or another.

* obviously you have fuel in the tank lol ? (just checking ;P ).
* Might be worth trying to bridge the supply to the primer pump / fuel pump :S ... but as you say theres 0vts from the supply :/.
- to double check when your reading the supply voltage are your grounding one terminal of the multimeter and putting the other on the supply wire?.. then are you turning the key to 2nd position?. - what does the meter read ? If the supply to the fuel relay is nonexistant try running a seperate 12vts supply to the pump :) maybe ...
* Another good shout may be to try your vagcom again now youve charged it or after you leave it on trickle overnight. If you can get this to communicate could prove very useful.
* looking through the electrical manual a chap uploaded on here it would seem that if the immobilizer was playing up you would see error messages on the dash/fault code reader.

Sorry to not be much use bud. hope going over a few things will reveal the issue.

Jon.
 
* I think we're definately onto something with the fuel pump not priming / running ( No supply/trigger ) ! .. get investigating buddy :D.
 
I've got a feeling that the fuel pump primes when you open the passenger door, not the drivers (possibly down to the left hand drive setup). Not sure if this is true or if its any help.
 
Went to the car this morning, and no luck with the dash light they are still only half illuminated. So what happened the previous day was probably a fluke.

Did a bit of checking,
-the car won't bump start, so can't check the electrics when running. But all window, mirrors, sunroof etc are working despite the dash only being half illuminated.

-and the fuel pump doesn't prime, regardless of what door you open. Checked this on my friends RS4 and pump primes on opening drivers door on his. It also doesn't prime when you put it in the ignition and turn the key. I checked the signal voltage at all stages of trying to start it but nothing at any stage. As I said earlier that I can manually activate the relay (removing the cover and pressing it) but it wont start then either. And I can hear the pump trying working when I press it.

- the vagcom won't communicate with the ecu as the dash appears not to be working properly

- the immobilizer light on the dash goes out as it should, it seems like the only thing on the dash that is working!

I was contemplating bridging a 12v supply to the signal for the relay, but part of me is concerned about how I would feel if the smoke doesn't stay in the ECU! :Flush:
 
This happened to Jojo didnt it? Was his fuel pump fuse.. Check all the pipes going to the FPR aswel
 
All the fuse are fine I'm afraid. There is no voltage going to either side of the fuse terminal, as the relay isn't getting it's signal to pulse. If I manually activate the relay the pump works so it looks like a wiring issue somewhere between the battery and the fuse board/dash.
 
Twincamman ,

Hopefully you are getting somewhere bit by bit.
When you say manually activate the relay do you mean supplying it with a seperate trigger ? 12vts? (you mention removing a cover and pressing it ?)

Taking into account whats been already said i would agree with your last statement.

But bearing in mind that even when you manually activate the relay it still doesnt start there seems theres more to it :S..

Going on what you said about the fluke it almost seems like theres something rather intemitent about the situation like sometimes its ok others its not. Surely a loose connection ? or faulty relay...

It would be great to have a look over it with you but sadly your miles away :/...

Dont give up :D.

Jon.
 
Last edited:
Jon,
when I said manually activating it I mean't removing the cover and pressing the actual relay contact, not supplying the trigger with 12v.

I'm thinking loose earth that the dash is more sensitive to than the rest of the car. It's looking like I'm going to have to start at one side of the wiring loom and make my way down to the other, and that mightn't even sort it.

And your right it would be a long way to travel for free beer....
 
TwinCamMan said:
Jon,
when I said manually activating it I mean't removing the cover and pressing the actual relay contact, not supplying the trigger with 12v.

I'm thinking loose earth that the dash is more sensitive to than the rest of the car. It's looking like I'm going to have to start at one side of the wiring loom and make my way down to the other, and that mightn't even sort it.

And your right it would be a long way to travel for free beer....
Click to expand...

If you are about to start looking at your wiring loom, then I'd recommend you have a look at the earthing point by the Bose sound system/sub woofer(not sure if you have it?). I remember installing my AndyMac stealth sub many years ago, and didn't get a good earth back there, and the whole dash was dimming like it was possessed whilst driving!
 
Just to add to this.

My mate got his s3 a few month ago, was known to have a dodgy fuel pump. The car would sometimes no fire or even turnover, he would have to pull the keys out, get under the car and bang the fuel tank, once he'd gave a few hits, he'd put the keys back in and you would here the pump prime then the car would start.
Last month it completely failed and we had to change it, a job that i can say was a pain in the **** literally haha.
Anyway, new pump and the problems gone.
 
Keeping my eye on this thread, My V reg AGU 1.8t is giving me similar problems and MOT is due very soon (Tomorrow). :ermm:
 
Just an update, unfortunately I'm not too much closer.

I left the car for a week as I had reached the stage where I was contemplating sorting the problem once and for all by putting a match in the petrol tank and walking away. I accidentally left the brand new battery connected and on returning 6 days later, (work commitments) before I even put the key in the ignition I checked the voltage. Only 7v! And battery is so bad the charger won't even register it strong enough to charge it now.

From this I'm thinking that the live must be partially earthing somewhere pre-ignition. And a dodgy earth is looking less likely.

Anybody have any thoughts on this...... Before I do actually resort to the matches!

Hustla101: Did you get sorted?
 
my money would be on the fuel pump or a decomposed fuel filter or possibly faulty injectors

second to that earth straps (but you've check them)

i think you need to take a voltage from the battery and monitor it as you unplug fuses, if you find a jump in voltage, you know your problem is related to that particular fuse / circuit
 
Just to let you know what the fault was in the end. The two small grub screws at the end of the ignition barrel had started to vibrate loose, this in turn let the connector block at the end of the barrel move a bit and only let a small amount of voltage pass through the weak connection. This was enough to half illuminate the dash lights but not enough to allow it to pass through the immobiliser. While I could get the VCDS to communicate with it on occasion it never threw a code for the immobiliser but gave the code of "01177 - Engine Control Unit 49-00 - No Communications" instead. Hope this can help someone in the future.
 
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