Alfa Romeo Forum banner
1 - 20 of 28 Posts

·
Registered
Joined
·
257 Posts
Discussion Starter · #1 ·
Morning all,

I am getting the engine light on, VDC ASR and Hillholder , no cruise control , Unavailable and the fuel gauge dropping to zero when the fault occurs. its showing a P0564 (multi function input circuit 'A') and p0100 (MAF)

i have changed the MAF ,brake and clutch switch and and checked the Injector wiring , they are working fine .

the fault occurs when you press the brake pedal and hold it about half way for more than 3 or 4 seconds. all the warings come up and the fuel gauge drops to zero. and when plugged in to an examiner the MAF reading drops to zero too.
The fault clears if you apply more OR less pressure to the brake pedal. And the Maf starts to read normally again

i have even disconnected the brake pedal wiring and so as to rule the pedal switch out and the fault still triggers.!!!

iv also disconnected the ABS unit and still occurs!!?????


help urgently required please






martyn
Edit/Delete Message
 

·
Registered
Joined
·
896 Posts
battery u/s

How old is your battery ? They need 100% batteries or your get all sorts of errors . try trickle charge overnight with one of the modern charger s with a retention charge on it.
 

·
Registered
Joined
·
257 Posts
Discussion Starter · #4 ·
ill give it a go , but surley someone else would have this problem if it was just a flat battery ? its something to do with the pedal being at a certain position . and nothing to do with the switches . i have just ordered an abs unit .
other than that it can only be the ecu or the body computer ??
 

·
Registered
Joined
·
896 Posts
ill give it a go , but surley someone else would have this problem if it was just a flat battery ? its something to do with the pedal being at a certain position . and nothing to do with the switches . i have just ordered an abs unit .
other than that it can only be the ecu or the body computer ??
How does the ECU know where the brake pedal is /position wise/ or is this a red herring. And its something to do with what is happening within the braking system at that point of travel.

Check the earthing straps apparently they snap their is one under the battery tray Ithink on desiel. Not sure on yours. Quick check run a jump lead to neg term battery to some shiny metal to make a good earth.

Just a thought
 

·
Registered
Joined
·
411 Posts
if you have the battery off your car (possibly for a while) and you hook it up. Sometimes the brera goes into some mode where the VDC warning is on. And the fuel gauge doesnt work.. and all the other symptoms... I think also like the power windows dont work properly. This could well be a battery problem, the boot might not open as well (fix this by pressing the internal lock in the middle console twice). (ive got a MAF issue as well at the moment). I would give the battery a good charge, or get a battery tester from the bay.

that maf error. P0100 basically means the maf is either not working or not connected. If its not working its usually accompanied by another error. The MAF needs 12volt to run. So again it could be battery. You could test the MAF voltage with a multimeter. Connect the black to the battery negative. and connect the red to PIN2 in the MAF socket (disconnect it). Anything less than 12v and I dont think the MAF will operate. (note Im not 100% sure its pin2 theres 5 pins. I think its pin 2. If you have the Maf disconected though you cant fry anything in the MAF.

So yer this could well be battery. It might be a funny gremlin that your battery sort of has some charge but isnt kicking out enough volts or something. Multimeter on it might be worthwhile.
 

·
Registered
Joined
·
257 Posts
Discussion Starter · #7 ·
The maf only stops working when the fault occurres. As soon as it clears the maf shows as working again . You can see the reading drop on the examiner to zero , then as soon as you press the pedal harder the fault clears and the maf starts working again . So something I telling the maf to stop working when te brake is pressed . But with the pedal switch disconnected I don t know what is telling it to stop. I changed my battery with the new one out if my brothers gt not so long ago and the fault remained . The fuel gauge drop is caused by the maf being told to stop working , as the same happens if you disconnect the maf completely . The strange thing is that the fault only happens at a specific point on the brake travel ( quite near the top) so what else would know where the pedal is or how hard you are pressing the pedal ? Is there a brake pressure sensor somewhere ? My car has been to three mechanics and an auto electrician and they are all stumped . ;(
 

·
Registered
Joined
·
411 Posts
I feel your pain mate. but I think you gotta go to a main dealer. this sounds like a gremlin that could be hard to diagnose. Are you 100% sure you have the right spec battery?

I dont think there is a brake pressure sensor. You have the abs or brake sensors, and if they are having a problem I think the VDC will go unavailable, but you should not get all the other issues like hil start power windows etc... so I dont think its a brake sensor. It sounds electrical but i am really not sure.
 

·
Registered
Joined
·
257 Posts
Discussion Starter · #9 ·
unfortunately i have been to a main dealer !! they said it could take hours of fault finding . and its also been to some very well known alfa specialist .

i agree that its definitely a volt drop telling the maf to stop working . the trouble is what .

my new abs unit has just turned up so i will change it anyway . you never now it could be the abs ecu . there is definitelya communication issue between the abs unit and the main ecu . Apparently the data is getting confused .

but why is another matter??

any other suggestions?

;(
 

·
Registered
Joined
·
257 Posts
Discussion Starter · #11 ·
no i hav nt actually . i will give it a go later . i suppose i could also measure the maf volt reading too. does any one know which pin is the live one on the maf?

martyn
 

·
Registered
Joined
·
701 Posts
no i hav nt actually . i will give it a go later . i suppose i could also measure the maf volt reading too. does any one know which pin is the live one on the maf?

martyn
Why worry about the MAF, when it only occurs at same time as other faults...Its something common, and reading through what others has experienced, i think you believe too much in a ECU that gets confused by something completly different & then spitting out faultcodes that has nothing to do with the actual fault ;-)
 

·
Registered
Joined
·
257 Posts
Discussion Starter · #13 ·
sorry , i did nt quite understand the second part of that ?;P and doesnt the alternator supply the power when the engines running ? is it worth checking that if there is a volt drop? i forgot to say the fault doesn t occur when the engine is off or on ignotion only .
 

·
Registered
Joined
·
701 Posts
In my opinion, you should just forget the MAF for now & measure battery before & when fault occurs (with engine running if thats required), to see if you get any strange results when fault occurs, cause something common must be the cause of all your faults (ECU is the engines computer :) ) Alternator charges & maintains the battery, yes, and yes, its a voltage-drop you should be looking for :)
 

·
Registered
Joined
·
257 Posts
Discussion Starter · #15 ·
i agree there is nothing wrong with the maf. iv had three ! ha ha . but when you say it s something common what the hell could it be ? if its not the battery , then i would nt know what else to try ;)
 

·
Registered
Joined
·
257 Posts
Discussion Starter · #19 ·
Well I checked all that out , and had 12.7 v at the battery when the car was off and 14.4 when started and the altenator kicked in . And no volt drop when the fault occurred ????
 

·
Registered
Joined
·
701 Posts
Really strange :-( what about loose wiring...Theres also a switch for the clutch..Maybe its acting up when pressing the brake-pedal...Long shot, but must say you found yourself 1 of the good faults.. :-(
 
1 - 20 of 28 Posts
Top