Car wont crank??? help please

S3KO4

S3KO4

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Hi, I have a huge issue a mate lent me his spare working alternator but now it wont even turn. I have checked:

All the fuses on the side of the dash.
Fuses/plate on the battery
Earth wiring on under the battery

still no luck.
all the dash/instruments work lights work and stereo works. but the engine wont budge. doesn't even try, I the TB is silent at start, mine always makes a bit of noise before ignition.

please help me out..

could it be ECU? or clock issue? imobilizer? car lock up like usual..

how do I reset the imobilizer?
 
Was it working before you changed the alternator?

Immo or ECU won't be affected in stopping it cranking anyway
 
eveything was working fine. until yesterday when the garage placed a volatage reader on the battery after that it didn't make any attempts.

there is no noise at all, I have a feeling its the imobilizer, as I don't hear the TB or the fuel pump. everything else works. I am soooo annoyed.

can I reset it with the vag com I have?
 
sure your battery isn't flat?

Immob works on the ecu and clocks. even if it took the ecu out the car it would still work you plugged it in! Immob would start the car anyway and then cut it out after 2 seconds if it was that!

"until yesterday when the garage placed a volatage reader on the battery after that it didn't make any attempts."

if i read this right the garage put a volt meter over the battery and now it wont work? Maybe the shorted the battery, wouldn't suprise me if they've blown it up!
 
beachbuggy said:
sure your battery isn't flat?

Immob works on the ecu and clocks. even if it took the ecu out the car it would still work you plugged it in! Immob would start the car anyway and then cut it out after 2 seconds if it was that!

"until yesterday when the garage placed a volatage reader on the battery after that it didn't make any attempts."

if i read this right the garage put a volt meter over the battery and now it wont work? Maybe the shorted the battery, wouldn't suprise me if they've blown it up!
Click to expand...

Thanks for all your replies. I have everything else working on the car thats what is puzling me, lights still power up full beam wippers, etc. and i tried to run it direct from a larger batter no luck.

my question is.. is there any specific wire or relay for the engine to start that I can check..

what are the two relays for behinde the air box? I know some a3 dont have these... but was wondering if they are meant to be for the engine!
 
I am thinking it could be the fuel pump relay. as it doesn't prime up like usual. does anyone know which one it is ? I know it's under the dash behind the fuses but don't know the exact one.
 
Could it be relay 100 for the ignition?
or relay 409 for the fuel pump?
 
double check your wires mate as the cable runs from your starter motor to the alternator!!!
check if you are getting a live 12v feed on the starter and check i think the small plug on the starter also when trying to crank the engine over!!!
 
checked the starter motor wires took the line off and gave it a good clean still no joy. it has to be the relays will update when I find it. I always seems to get issues very uncomon on the 8L !
 
also have you checked the fuses ontop of the battery tray?in that flip up compartment!!
 
Ok everyone after another long day Sunday. I still have not sorted the issue. I have check all the electrical and including ignition barrel, the issue is power (+) does not reach the starter motor. I managed to crank it direct from the battery and that work ok. but there is no live power from the (+) connection at the starter motor everything else works ok. I took it for a drive and it felt pretty normal.

My question is: is there a relay for the starter motor? I am guessing it could be relay 167 or 248 but need someone to confirm tried the manual from Welly's but it doesn't specify!
 
There is no relay. Just a wire from the ignition switch directly to the starter motor solenoid, and a big fat live from the battery to the starter.

Are you saying there is no 12v at the big wire or the small one?

Follow the small red/black wire from the starter back up the loom, and check for any breaks? Theres one join in this wire, at the "plenum chamber"
 
Thank you very much, I have tried to look for it from the barrel there are few about 6 of them black and red I know its the top one (thinner) for the ignition, but it goes into the big loom together behind the dash.

if I fail to find one can I just get another wire rooted to the barrel or would that cause some issues?

there is (-) connection big one but not (+) small red and black. voltage is 0
 
So is there a hard switch to reset the car, some cars have them under the bonnet and some under the driver seats!
 
No.

At the starter motor there are two terminals. One has a large black wire bolted onto it, and the other has a small red/black wire bolted on. The large black wire should be 12v all the time. Small one should go to 12v when you turn the key.

If you apply 12v to the small wire the engine should crank. You need to find the matching wire at the ignition switch, and check that it goes to 12v when you turn key. If it doesnt the switch is broken.
 
I checked all that, there is a specific one black/red on top of the barrel that stays off and when I turn to the ignition position there was (+) 12.4v but the power doesn't reach the starter's small connection red/black wire. :(
 
audi upgrades
Nice one I think I will, but I will take it to auto electrician first see what they think.
 
just a quick one mate u mite have voltage!! but do you have current??
seen it before on a circuit were there was voltage but no current!!
 
S3KO4 said:
Nice one I think I will, but I will take it to auto electrician first see what they think.
Click to expand...

have you solved it I'm having the same issue its giving me a headache its on a4 b5 1.8t but the wiring is pretty much similar, the problem is exactly the same as yours done everything and hot wired it to confirm everything work just doesn't start or crank with they key by itself.

Also the red/black from the starter goes into some relay in ECU but apparently there are no relays according to most posts and circuit diagrams. I'm thinking whether there if their is brake between in the red/black wire from starter to ignition switch and whether to just feed my own new wire from the starter to ignition switch.
 
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