Limp mode + Blown fuse

[smokiebbear]

Hi Everyone,

I have a 2009 VW TSI 118 Comfortline and it's blown the 10a fuse under the bonnet that appears to run the supercharger.

Engine fault light it on (orange) and it won't rev past 3k (limp mode)

The following issues are .....

G Scan tool diagnosed

P10AC Supercharger - short circuit to earth
P10AD Supercharger - open circuit


It has 109,000km on engine, it's not making any funny noises and the problem occurred when I parked it in my garage the other night it (free boosted in neutral at idle) and I shut it down then it dosed off and fault light came on.

When I replace the 10a fuse it blows straight away. When I put in a 15a it blows straight away. When I put in a 20a fuse it starts building boost through the supercharger at idle (900rpm) and there is a loud clicking noise as if something is trying to engage/disengage. I have left the fuse out and currently driving around in limp mode.

I'm thinking it might need a new supercharger magnetic clutch which I believe is engine out to replace (part of water pump).

Has anyone has this issue before and what was the final outcome?

Whilst I do appreciate people trying to help I'd much rather not confuse myself more with people who know less than me about cars or are just guessing what may be the issue I find are generally in fact more of a hindrance than helpful.

Please only comment if you have previous experience with this issue/one similar or may know what it is.

Thanks in advance

[h100vw]

Leave that 20A fuse out mate before you melt something big time. Fuses generally blow at twice the rated value. So you are dragging over 30A through the wires that were previously meant to handle 10-20A max.

Can't offer any advice on whether the clutch is bad or not. However from experience with avionics, I wonder if the wiring is damaged rather than the clutch. With the big fuse fitted the clutch gets current adequate to engage as the fuse isn't blowing.

Hard to diagnose without a wiring diagram in front of me. Although, I'd be removing the fuse and buzzing between the fused side and ground. Obviously, it should be open.

I'd also do the same from the plug on the supercharger. I am guessing that the trigger comes from the ECU, maybe via a relay, so a diagram would be really handy to go further.

Gavin

[smokiebbear]

Fuse is out, it was only in for 1 min testing purposes to see if supercharger engaged.

[smokiebbear]

The clicking sounds like a solenoid and it was pulsing every second or so.

[JB's Dub]

Fuse for supercharger blown? That's an issue with the Supercharger clutch/waterpump. Common issue. Ive fixed a few!

And you can replace it with the engine in the car. Its fiddly but a hell of a lot faster than removing the engine.

[smokiebbear]

How long did it take to replace the SC Clutch/waterpump? Any idea on what the parts cost?

[JB's Dub]

It takes around 4 hours with a good pace. But I had done a few of them and being in a VW workshop, I had the specific tools required to make the job easier. As for parts cost, Im unsure.

[smokiebbear]

It takes around 4 hours with a good pace. But I had done a few of them and being in a VW workshop, I had the specific tools required to make the job easier. As for parts cost, Im unsure.

Based on what I what I'm experiencing would you recommend I take steps to replace the SC clutch/water pump and fixing the issue?

I have been quoted around $400 for the part

[JB's Dub]

Yeah. I mean, If I was working on the car, id check wiring first, then id measure the electronic side of the clutch to confirm the short circuit. But everyone I have done, has always been the clutch.

[smokiebbear]

Did they show similar symptoms and fault codes?

[smokiebbear]

What specific tools are required?

[JB's Dub]

Just various minor tools, like tensioner locking tools, vacuum bleeder for the cooling system etc. The handiest tool is the locking tool for the supercharger allowing you to remove the pulley off it. It makes life a hell of a lot easier.

[Snail Style]

Test wiring first, it's not common for a solenoid to blow a fuse as it is basically just a switch.

[smokiebbear]

Test wiring first, it's not common for a solenoid to blow a fuse as it is basically just a switch.

I'm going to go over it on Friday and check all the earth's. Wouldn't the fact the supercharger engaging at 900rpm in neutral suggest that its more than a wiring issue? It had thrown another fault code initially before we reset it to try and clear the limp mode and one was a boost issue, possibly an over boost which would suggest the supercharger wasn't disengaging and the constant clicking is possibly the solenoid trying to disengage it but it's unable to. The 2 fault codes could be present because the blown fuse is preventing it from making a complete connection?

[smokiebbear]

Just various minor tools, like tensioner locking tools, vacuum bleeder for the cooling system etc. The handiest tool is the locking tool for the supercharger allowing you to remove the pulley off it. It makes life a hell of a lot easier.

Where can I get myself a set of these tools? Are they available from anywhere?

I'm going to do this myself on Friday on the ground with the car on ramps. Do I go from underneath the car to remove it or pull off the intake and go in that way?

Any suggestions?