Help with fuse 4, keeps blowing!

[alyp123]

Hello!
I’m looking for advice or to see if anybody else has had a similar problem or any ideas.
Car is a Leon MK2 FR+ 2010 facelift with 2.0 TSI engine, code CCZB. (211).
Fuse number 4 keeps blowing, it is the box in the end of the dash on drivers side. In the circuit is reverse light switch(so no auto sensor activation), interior mirror so no anti dazzle, oil level/ thermal sensor so warning light is on in dash, TCS and TPMS buttons, I also believe it to be connected to heating but not sure which element.
I have tried unplugging all of the components at different times and regardless the fuse just keeps blowing, causing me to believe it is a short circuit to ground causing the fuse to keep blowing. Sometimes it can last a 10-15 minute journey and be fine and then as soon as I turn ignition back on again it blows. Other times it blows before I even turn the engine on. The oil level sensor has been changed, and I have checked all engine bay wiring going to each component and all is okay and intact, can’t find any breaks in the wiring anywhere or any short circuits. All ground connections look and feel intact and good condition. Battery not too old, good condition. Radiator fan is constantly running as soon as you turn the engine on from cold, presumably a fail safe from the oil thermal sensor?
please let me know if anyone has any ideas!

 

[ChocoMilkShark]

Have you used a ob2 reader to see if any errors are coming up if your getting lights on the dash there should be a error logged.

Sent from my XQ-AT51 using Tapatalk

 

[alyp123]

Yes, I have scanned it a few times and the only codes that have come up are a code for AC high pressure sender when I left it unplugged as part of testing components. And every time the fuse blows I get a code for the oil level sensor which is in the ECM and also Dashboard module. You can clear them and all is fine until the fuse blows again and then if I scan again, the codes return for oil level sensor, usually implausible signal or open circuit (because of the fuse blowing).

 

[mty12345]

Like you say, there must be a short to ground hiding there somewhere. I would disconect the battery, then put a multimeter in continuity mode between the power side of that circuit and ground, then work your way along all the wiring moving it all about and listening for a beep from the multimeter. Can't really think of any other way of tracking it down really.

 

[TheSwede]

Hi.

The tread below helped me for for 5 years ago. Had similar problem with my sons Leon linea R 2009.

The vcds fault code was :

• 00819 - High Pressure Sensor (G65)
• 009 - Open or Short to Ground

The problem was washer jet heating/short circuit.

https://www.seatcupra.net/forums/threads/puff-of-smoke-blows-fuse-no-4.428531/#post-4646278

"The passenger washer jet has two wires and they had fused together and melted the washer jet connection. So for now I've cut the wires sleeved them until I purchase a new part."

I just did the cut en left it without power/heating. Problem solved!

/Peter

 

[alyp123]

I saw this post, and thought ahh must be this! Removed the cowling containing the washer jets from the bonnet and discovered that there are no heated jets on this one.. no wires just washer hose and spray jets. Thought I was onto a winner
Going to remove battery tray and just start tracing and checking all wires I think.
Still not managed to get anywhere with it.

 

[TheSwede]

I spent a couple of days hunting the problem before I fund the forum tread, in this case it was spot on.

Hope you soon will find something!

 

[alyp123]

UPDATE for anybody interested or with a similar problem in the future.
After removing the airbox, battery and battery tray much more of the wiring loom exposed and revealed at the back near to the bulkhead the source of my problems.
Basically the loom had been chafing on the back of the battery tray and a 5V signal wire ended up getting fused into a ground wire, causing a short circuit which meant it kept blowing the fuse no matter what I did.

 

[mty12345]

Whats the year and engine code

UPDATE for anybody interested or with a similar problem in the future.
After removing the airbox, battery and battery tray much more of the wiring loom exposed and revealed at the back near to the bulkhead the source of my problems.
Basically the loom had been chafing on the back of the battery tray and a 5V signal wire ended up getting fused into a ground wire, causing a short circuit which meant it kept blowing the fuse no matter what I did.

good work, glad you found it