Seat mechanic, stuck with a non start prob ??

jay b · Feb 19, 2009

Hi guys, Ive got a 56 reg Leon FR TDI BMN engine, in at work confusing me! I deal with these cars all the time but have never had a non runner on one of these.. the basics...
engine turns over but wont run. Timing checked, all fine. Fuel pump working. Diesel seems clean and is pumping up from the tank. Havent yet carried out a fuel pressure test tho. The only fault code in the engine is "main relay malfunction in ciruit" Followed giuded fault finding, checked the power suply relay (even tried one from annother leon) and fuse, all ok, clicks when ign turned on. It seems the 2 main power feeds to ECU arnt found so I have started to strip the wires between the relay (in the engine compartment fuse box, nearside) and the ECU. I have found 2 slightly chaifed wires running to the ABS, had rubbed on the battery tray. Fixed them but the fault code wont go away, as soon as i eraze it, it returns. I will hopefully find the cause tomorow but if i havent i will be back on here with the exact fault code. It seems to have even baffled the technical help centre. Anyone else had this?
Maybe the fault code has nothing to do with the non start, but my aim is to clear the code before i try next steps...
Anyone that helps me will be helped in return, but please dont think that i will be able to answer lots technical questions all the time, I have enough of Seats at work every day! I need to get away from them in my spare time lol hope you understand! Thanks.

robdf2 · Feb 19, 2009

try the relays where the battery is the grey square ones, a guy had similar problem on his cupra , it may be different layout , but i havent seen FR engine bay.

how much comission do i get if it fixes it? :blink:

Tam · Feb 19, 2009

anyone remember the F21 fuse thread ...??

truCido · Feb 19, 2009

Tam said:
anyone remember the F21 fuse thread ...??

pop a fuse into the F21 slot and then try starting the car?

Fl@pper · Feb 19, 2009

ooooh sounds like a meaty one, those wires weren't part of a bunch more per chance were they ?

had a mk1 that was a nightmare for loads of recurring codes once with similar stipped wires under the abd unit and further up the loom had melted more together, then on stripout and close inspection revealed cause by accident damage.

even known water travel along a loom from a headlight into a dashboard on others too so i feel for ya mate

good luck though - keep us informed - interesting this one

jay b · Feb 20, 2009

The first thing i did was check every single fuse with a test lamp, and i also put a fuse into empty slots yesterday, the car obviously came in on a recovery truck so you never know whos been fidling with it. But i will triple check them just incase! thanks. The grey power supply relay has also been substituted and it still wouldnt clear the fault code!

philsip · Feb 21, 2009

jay b said:
Hi guys, Ive got a 56 reg Leon FR TDI BMN engine, in at work confusing me! I deal with these cars all the time but have never had a non runner on one of these.. the basics...
engine turns over but wont run. Timing checked, all fine. Fuel pump working. Diesel seems clean and is pumping up from the tank. Havent yet carried out a fuel pressure test tho. The only fault code in the engine is "main relay malfunction in ciruit" Followed giuded fault finding, checked the power suply relay (even tried one from annother leon) and fuse, all ok, clicks when ign turned on. It seems the 2 main power feeds to ECU arnt found so I have started to strip the wires between the relay (in the engine compartment fuse box, nearside) and the ECU. I have found 2 slightly chaifed wires running to the ABS, had rubbed on the battery tray. Fixed them but the fault code wont go away, as soon as i eraze it, it returns. I will hopefully find the cause tomorow but if i havent i will be back on here with the exact fault code. It seems to have even baffled the technical help centre. Anyone else had this?
Maybe the fault code has nothing to do with the non start, but my aim is to clear the code before i try next steps...
Anyone that helps me will be helped in return, but please dont think that i will be able to answer lots technical questions all the time, I have enough of Seats at work every day! I need to get away from them in my spare time lol hope you understand! Thanks.

did you have any luck with this then? a few 2.0tdi a3's have had this in my workshop! results would end up being part of the wiring loom that mostly needed exchanged!

it can be anything in theses engines, but as GFF has stated check all the major and minor relays under the dash! it could be a simple as that man?

jay b · Feb 23, 2009

philsip said:
did you have any luck with this then? a few 2.0tdi a3's have had this in my workshop! results would end up being part of the wiring loom that mostly needed exchanged!

it can be anything in theses engines, but as GFF has stated check all the major and minor relays under the dash! it could be a simple as that man?

Hey thanks for that, yeah whilst this engine is quite new to Seat, i guess you Audi guys have seen these particular engines with higher miles as they have been using them for longer, your right, anything can trigger this fault! I have had some very interesting info from the technical dept today... its a long and quite confusing explination of what may be causing it, but it does make sense. I have some checks to carry out tomorow, it will take a while but if Its the cure then I will let you all know. Every relay and fuse has been checked and even swapped to try, its a lot deeper than that in this case.

jay b · Feb 24, 2009

Problem found

problem found...

--------------------------------------------------------------------------------

Ok, to break it down a lot, the "main relay J271" doesnt exist, the guided fault finding program on the diagnostic machine sent me down the road of testing the power supply relay, not correct... its inside the ECU and is a reference to a fault somewhere in the injector circuit. Due to the PD injectors being inside the cylinder head, I had to remove the cam cover box and then individually unplug each injector, and check/ eraze the fault code untill it finaly stayed away, this only happend on number 1 injector, therefore the ECU cant recognise what all the injecors are doing, so it cut the power off to all of the injectors. With one unplugged, i cable tied the wire up safe out the way of the injector camshaft, bolted the cam box back on and tried to start the car, she ran straight away, on 3 cylinders so I turned it off and got a cheer from the boys atlast!! The fault lays in the electric Piezo part of the pump injector. These badboys cost over 500 pounds each, they dont go wrong much, which is nice! the cars under warrenty, so no cost to the customer.
These kind of jobs are a nightmare for us, but now ive found one, there will be more and now I, and you! know.
If the fault code related to the Injectors the first place It would have saved a lot of time, never believe that our job is easy beacause a computer tells us where the fault is, it doesnt always work like that.
Part is on order, hopfully the car will be running sweet and fully serviced by the end of the week. I must say I do like these cars a lot, I would have one if i wasnt a skint car technician

Tam · Feb 24, 2009

Wow, thanks a lot ... i'm sure at some point in the future this *will* help someone.

Out of interest what was the original fault code ... this may make searches later get this thread

Sounded like a lot of work went into tracking it down, and makes it worth knowing that if the first injector is faulty it stops all the others.. (poor design or just cost saving?)

Makes you feel good when you eventually resolve something thats been a complete and utter pain doesn't it

Hopefully the customer hasn't been to hard on you trying to get it fixed sooner.

dainott2105 · Feb 25, 2009

mmmm, im a little worried now as had the same turning over but not starting problem on my missus 57 plate fr tdi. Spent hours trying to get it started with no joy but disconnected the battery over night and then replaced the battery and problem has gone (been fine for 2 months since) so presumed that the battery had died, but could have been this issue and a reset solved it.

jay b · Mar 4, 2009

The fault code...

The car has now gone, running well. The fault code was 05399 p1517 "main relay elecrtrical malfunction in circuit" or when i ran guided fault finding, it had the same code but read " motronic current supply relay J271 electrical fault in circuit.
This is very rare, the first I came accross any way. I would have expected a missfire/ bad running, but not a total non start!! now i know...

philsip · Mar 5, 2009

glad to here this mate! wiring diagrams can be very useful some times! other times it could be something else triggered showing up as a fault! if you get any more faults like this you should post them up! its not intresting to the average person but for technicians it can be pure gold!

Poverty · Mar 5, 2009

jay b said:
problem found...

--------------------------------------------------------------------------------

Ok, to break it down a lot, the "main relay J271" doesnt exist, the guided fault finding program on the diagnostic machine sent me down the road of testing the power supply relay, not correct... its inside the ECU and is a reference to a fault somewhere in the injector circuit. Due to the PD injectors being inside the cylinder head, I had to remove the cam cover box and then individually unplug each injector, and check/ eraze the fault code untill it finaly stayed away, this only happend on number 1 injector, therefore the ECU cant recognise what all the injecors are doing, so it cut the power off to all of the injectors. With one unplugged, i cable tied the wire up safe out the way of the injector camshaft, bolted the cam box back on and tried to start the car, she ran straight away, on 3 cylinders so I turned it off and got a cheer from the boys atlast!! The fault lays in the electric Piezo part of the pump injector. These badboys cost over 500 pounds each, they dont go wrong much, which is nice! the cars under warrenty, so no cost to the customer.
These kind of jobs are a nightmare for us, but now ive found one, there will be more and now I, and you! know.
If the fault code related to the Injectors the first place It would have saved a lot of time, never believe that our job is easy beacause a computer tells us where the fault is, it doesnt always work like that.
Part is on order, hopfully the car will be running sweet and fully serviced by the end of the week. I must say I do like these cars a lot, I would have one if i wasnt a skint car technician

We have computer program diagnostics on boilers. I fookin hate em with a passion as most of the time they are wrong, and send us in the wrong direction of the fault.

Congrats on fixing the car, know how frustrating things like this can be

Fl@pper · Mar 5, 2009

getting to clever for their own good these cars

well played by the way

b8er1234 · Sep 21, 2012

after trawling the internet I found this forum luckily!! my car yesterday while I was driving completely cut out. Now the car turns over but just doesn't start. I assume this is the same problem with the injector? I did receive a letter from Seat a few months back as they were doing a recall on the 170 engines as there was a problem with the piezo (think spelling ok) injector so could only guess this would be the issue?

big rich · Sep 21, 2012

Yeh its the most common thing for these, the engine ecu shuts off all injectors if one faults due to the drivers in the engine ecu, stupid really as you dont really want to be cutting out on the fast lane or pulling out a junction etc...

David101 · Sep 21, 2012

big rich said:
Yeh its the most common thing for these, the engine ecu shuts off all injectors if one faults due to the drivers in the engine ecu, stupid really as you dont really want to be cutting out on the fast lane or pulling out a junction etc...

I wouldn't say stupid as seat have programmed it this ways as a safety measure so if there was something actually wrong it wouldn't do further damage. But hopefully if it does happen whilst driving your should/ I would have thought go into limp home... But could be wrong.

big rich · Sep 21, 2012

David101 said:
I wouldn't say stupid as seat have programmed it this ways as a safety measure so if there was something actually wrong it wouldn't do further damage. But hopefully if it does happen whilst driving your should/ I would have thought go into limp home... But could be wrong.

i wouldnt call it a saftey measure, if it happens when your driving it literally just cuts out and wont restart which is dangerous hence them being recalled.

David101 · Sep 21, 2012

big rich said:
i wouldnt call it a saftey measure, if it happens when your driving it literally just cuts out and wont restart which is dangerous hence them being recalled.

I have only had my seat for less than two months so I don't know if they did cut out when driving or they went in to limp home and then when u start it again it wouldn't start. If ya know what I mean.

Seat mechanic, stuck with a non start prob ??

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