Fuse 26 Blowing, Need help!

[kyle92]

Evening chaps,

As of late my polo has been rather hesitant to start in the mornings, as if maybe the glow plugs were not getting up to temp or the battery was a bit flat, so I have been plugging my motorcycles optimate 4 onto the battery overnight to try and give it a bit more life, this has help, anyway...roll on a few days of being on the optimate.

I jumped in my 2011 1.2 tdi, it started without issue but the glow plug light was flashing, I turned the engine off and attempted to restart it, it wouldn't turn over.
Tried disconnecting the battery and leaving it, nothing, eventually found out that fuse 26 was blown, so replaced it, as soon as you turn on the ignition it blows.

Does anyone have any ideas that are not just 'a broken wire somewhere' as not only have I already thought of that but is going to take me an age to trace all the wiring back and look for a short.
I am thinking perhaps the starter relay or the glow plug relay is buggered and blowing it, maybe even a buggered starter motor.

Any help would be appreciated.

Cheers,
Kyle

[iichel]

Find the fuse overview and see what is attached to fuse 26. Disconnect one by one to see whether any faulty devices or sensors blow the fuse.

[kyle92]

All of the relays are behind the drivers lower facia, from what I can see and have read, it is an absolute c*nt to get to the relays.
The only relay I can access is the glow plug relay

However I am starting to suspect it may be the starter motor or one of the starter relays as I had issues with the stop start not working a few times (well a lot).

[iichel]

So this are the relays powered by fuse 26.

Screenshot 2020-11-10 at 11.03.47.png (87.13 KiB) Viewed 1743 times

The starter relays are placed in the bottom row of the relay carrier, second and third one from the left.

[amer6R]

Plug it i to diagnostics it will help you so much to trace the issue. odis or VCDS

[kyle92]

That is quite helpful iichel,thank you, I will pull them tonight and see what I can diagnose, I have some spare relays kicking about somewhere so I might get lucky.

I plugged it in and checked for codes amer6r, there were none.

I have absolutely no idea how to access the relays via stripdown, the manual does not show it, only states their location and I have seen people on other forums saying it is an absolutely nightmare taking hours to get to them.

[amer6R]

Well, remove the side panel on dashbosrd ( like the factry one that covers the fuses on MK4 golf and Mk5

[kyle92]

Amer6r, from removing the side panel at the door and the fuse panel, I can't see whatever variation of hidden bolts are keeping everything else in places.

I removed both starter relays 1 at a time and put a new fuse in, turned the car on and the fuse still went, it can't be them, although the small of the 2 fuses had something rattling about inside...can't be good.

[iichel]

So... now you remove all other devices in that list to see what's going on.
Air mass meter is the easiest, that's located right next to the air filter. Next the power steering unit which is a lot harder to reach and next up are the other two (even though I think your TDI doesn't have the crankcase heater element)

[kyle92]

I managed the air mass meter (nice and easy, no change unfortunately, the power steering unit...hmm very tricky indeed.

I too am questionable on the crankcase heated, I couldn't find any mention of it in the haynes manual.

My father and I managed to bump start it and I drove it to my friends garage, he is a porsche mechanic and has always fixed my polo, in fact he not long overhaul the cat on it, which I owed him several cakes and several bundles of notes for lol, it was some job!

The glow plug light was flashing and the power steering was completely dead, makes sense if that is on the fused circuit and that fuse is dead, although he actually agreed with me suspecting the starter motor and also mentioned he not long replaced a power steering module on a seat (same module), he said they were prone to failure but never seen one shorting, although he did have to completely remove the power steering system (and the basically everything else) to get the cat done on it lol

[amer6R]

Not the POLO fuse BOX, the GOLF FUSE BOX

thru there you could reach
also remove the light switch to peek to see the relays, reach thru the place i posted the pic. It's tight

[iichel]

The symptoms you describe match the blown fuse:
- no power steering because it doesn't receive the signal of ignition on
- glowplug flashing because the air mass meter is disconnected

To disconnect the power steering plug, you need to remove the battery and reach into the hole that you'll see. It's a bit tricky.
There are two or three plugs on top of it, you need to reach the connector with the three thin wires or otherwise disconnect the large connector with the brown and blue, very thick, wires.
I guess if it doesn't have a ground, it can't short out either...

[kyle92]

iichel, my polo is now with my mechanic, fortunately he is also thinking power steering as well as starter so I guess he will start with them first after doing a basic code check to be safe.

He is a good guy and he will do it right even if it takes him twice as long so I have every faith in his abilities, unfortunately his advantage being he does this for a living and has a 2 poster, it has been a fair while since I had to do electronic diagnostics on a car and trace a possible bad earth.

I will keep you updated but feel free to fling more ideas my way as I will continue hunting for them too.

[iichel]

Check for short circuits one by one. If that fails, you'll have a broken or shorting wire.
Then your options are to check the entire wiring loom or run a new wire to all devices fed by said wire/fuse.

[kyle92]

Evening Folks,

Apologies for the lack of updates, anyway I got a call back from my friend who diagnosed the fault as glow plug No.2, this was after he pulled the starter motor out, rebuilt it etc and noticed wear on it (113k miles so expected) and put the fault down to that.

Anyway, new glow plug in and no issues at all, happy days! Still, a glow plug was not high in my list of suspected items in the fused circuit that would be fusing it.

She is still lethargic in the cold mornings but we think that may be the other 2 glow plugs needing changed.

Also, thanks for the help chaps, it is appreciated!