Not starting DB9

[paulrog1]

Hi,

I've got a problem with my 2004 DB9, the car drove ok a few days ago, then I tried to start it yesterday and as soon as the key is turned to ignition on the whole car just dies, dead, sometimes i need to reset the battery yellow switch by the side of the battery, but the starter motor never even starts to crank the engine.

So I don't know if anyone has had this problem??

It's not the battery as it's only a couple of years old and on a battery conditioner.

I checked fuse F15 (starter relay) and all the others in the under bonnet fusebox and all good. Looking at some info online the under bonnet fusebox suffers from moisture ingress and eventually the starter circuit short circuits, maybe that could be the problem?

I checked to see the earth is ok to the engine I connected the alternator bracket to the battery negative, and no change.

How reliable is the starter motor? maybe the alternator?

Thanks for your help guys

[ian448]

hi Paul , dont count out a duff battery just because its only a few years old and on a conditioner , Ive had batteries give in long before that ( good quality one aswell) also had another one die within the space of 5 minutes .

I would try a jump pack or bump from another car before you start chasing your tail with fuses / relays. Eliminate the obvious first and dont assume anything

[Calinours]

I second this. First rule out the obvious - the battery.

Use jump leads with engine running on the other car.

[M1AGM]

Paul, you’re not having much luck with your Aston, hope you get it sorted fella. Can’t offer any advice other than to agree with the other guys about the battery.

[paulrog1]

M1AGM said:

Paul, you’re not having much luck with your Aston, hope you get it sorted fella. Can’t offer any advice other than to agree with the other guys about the battery.

Yeah thanks Andy, I've had a bad run of it, first the engine had a rough idle, rich running, eventually diagnosed a secondary bank inlet manifold leak, difficult to repair, but got there eventually, then the power steering pump went, but I found a good remanufacture, so that was repaired ok.

Now the car has this electrical fault, seems ok until I either turn the key to ignition on, or press the start button then the car goes dead so this morning I tried to start it using my campervan, but still no go, so it's not the battery.

I called a couple of AM inde's last week and although it's difficult to pin point down the phone they told me that the starter motors are normally very reliable to the point one of them has never replaced one but they have however replaced the under bonnet fusebox as they do get electrical circuit problems, so today I removed that, not a bad job, N/S wheel off, wheel arch liner off, then unplug loads of connectors. I will take it apart at work one day to see if I can find any issues, I will post back.

It could be the alternator, or maybe ignition switch??

If anyone has had this problem with their DB9 please could you let me know, thanks.

[Techno9000]

Don't forget it doesn't take much resistance at all in the high current path to the starter to create a large volt drop in the action of trying to start the engine which results in no movement from the starter motor.

I had this in a car, everything was fine on ignition on, but turning to start resulted in no motion from the starter and the instrument cluster went dark, the car seemed to die. On releasing the key back to ignition on, the instruments came back to life. When I found the issue it was the connection between the battery positive clamp and the high current wire leaving it.
I calculated the resistance to be around 0.02 Ohms, not much at all but when the cars trying to take a couple of hundred amps it comes to 4 volts and drops the terminal voltage to under 10 volts, not enough for the car electrics to operate.

Worth you considering. In your case the resistance may be somewhat higher, but the principles the same, check out (bypass) the positive connection at the battery.

[paulrog1]

Update on this -

My car is now fixed and running perfectly, I found there was nothing wrong with the engine fusebox, and all the connections to the alternator and starter motor were ok, so I jumped it again from my campervan and this time I was able to turn the engine over.

So I installed a new battery and that did the trick, the engine fired into life!!

I've never had a car battery that just completely died like that, normally the car would struggle to start, so initially I struggled to find the cause, i'm glad it was just outside my garage and not miles away!!!!

Back enjoying the car now!!!

[M1AGM]

Great news paul.

[Simpo Two]

paulrog1 said:

I've never had a car battery that just completely died like that

I've had two - a BMW and a TVR. You get in expecting it to start up as usual - and nothing. I had an S-Type which did it roughly once a week at random intervals, but that was an electrical fault capable of killing the battery overnight. Being somewhat easier to change than in a DB9, I got round it by carrying a spare battery and a spanner everywhere. Unbolt, swap, rebolt and carry on. A bit like an F1 nosecone change

It's good when they work isn't it!

[ridds]

The trouble with Lead Acid batteries is they hate being flattened.

Leave one flat for too long and the plates inside start distort and their capacity plummets. Don't believe the hype about battery conditioners either. They're a lot of nonsense imho.

Astons do not eat batteries unless there is a fault. Mine now sits for 6, 8, 10 weeks at a time with no issues. No conditioner or charger.

Previously 2 weeks and it could be flat. I've had a 3rd brake light error (3 LEDs staying on all the time) and the engine bay fuse-box corroded, voltage leaked across traces initially before finally shorting the starter solenoid circuit. That gave me a heart-attack one night.

For the sake of a £120, just grab 5 year warranty Yuasa battery from Halfords (roughly the price of a tank of fuel).

You won't have to buy another for 5 years as Yuasa very rarely question the warranty claims.