Hi.

I’ve got a strange one for you all.

When the engine is idling and the horn is sounded, the engine stalls. Upon restarting it judders and stalls again. It takes several restarts to get it running again. I’ve scanned with Carista. Sometimes it shows a fault with fuel rail pressure sensor, other times it doesn’t register a fault.

2014 L&K to 170

Any ideas?

Cheers

Dunk

You need a new battery.

Hi, thanks for the reply.

I was thinking that may be the case. 

don't use the horn while you need to accelerate !!!

Wise words!

I only used the horn because I was picking my mother in law up. I blame her

😁 Sound plan have you told her ?? 

Let’s see if I am able to charge her for the new battery 

On 26/05/2024 at 19:21, freedie said:

You need a new battery.

Sorry I don't buy that.

 

If the battery were that far gone it's hard to see how the car would even start in the first place but once running the alternator should provide the power to keep it going.

 

Does it happen if you instead turn the headlights on or even just flash them with the stalk, that will draw far more current than any horn.

If not then it ain't the battery.

Hi KiNeL

The reason I asked the question was that sounding the horn was the only thing that caused the engine to stall. I’ve never had any issues with starting when the headlights are on auto and the HVAC is also on.

I checked the battery and it was reading 12.18V. Obviously this is not ideal, but as far as I was aware, nowhere near problematic.

Does the horn sound normal (or at all) when operated? 

Hi

yes it sounds normal (twin tone)

12.18v is fine for a battery without the engine on, not so when running though when you should be seeing 13.5+

 

What, if anything, happens if you sound the horn whist actually driving?

Hi

 

When you get interaction between two seemingly unconnected electrical items, it can indicate a fault (e.g. bad joint) in something which is common to both.  Sometimes this is on the supply side, e.g. a shared fused feed.  However this is unlikely for the horns, as they would normally have a dedicated fuse.  Altenatively, it can be a problem with a shared Ground (Earth).

 

The system on the Yeti (and many others) is to common up multiple ground connections within the wiring loom.  A common ground wire (often of bigger cross section) is then routed out to a ground point somewhere on the body/frame.  There are a number of these, but each one is serving quite a few electrical items.  Any unwanted high resistance due to a bad joint will cause voltage drop.  When the horns are used, several amps will flow to ground, the extra voltage drop could therefore be upsetting something else connected to the same ground point.

 

I attach the schematic for the horns, which are powered via a relay driven by the onboard supply control unit.  The Treble Horn H2 grounds via Main Harness Ground connection 5.  The Bass Horn H7 grounds via Main Harness Ground Connection 14, and thence to Ground Point 1, front of right longitudinal member.

 

The horn push operates at low power levels and communicates with the Steering Column Electronics Control Unit via two "Clock Springs".  I think this part is unlikely to give your symptoms, but I include a diagram.

 

Time to check your ground points, which may only be possible by undoing them as any corrosion can be hidden from view.

If your battery is at an age where you might be anticipating a replacement in the foreseeable future don't rule it out as a cause of your problem. I've been lurking on this forum for 11 years and seen members tearing their hair out with strange and wonderous problems which all came down to a failing battery - even sometimes when the evidence suggested the battery was fine. I did experience this myself with odd and unrelated things happening when the car got to four or five years old, even though the car started every time without problems. I took the risk on replacing the battery (thinking it wouldn't be money wasted and would cost less than a couple of hours of mechanics time) and everything was back to normal. As Skoda say "Simply Clever" but for owners sometimes "Annoyingly Frustrating". It's only a suggestion if your battery is getting a bit long in the tooth however.

3 hours ago, Austin 7 said:

Hi

 

When you get interaction between two seemingly unconnected electrical items, it can indicate a fault (e.g. bad joint) in something which is common to both.  Sometimes this is on the supply side, e.g. a shared fused feed.  However this is unlikely for the horns, as they would normally have a dedicated fuse.  Altenatively, it can be a problem with a shared Ground (Earth).

 

The system on the Yeti (and many others) is to common up multiple ground connections within the wiring loom.  A common ground wire (often of bigger cross section) is then routed out to a ground point somewhere on the body/frame.  There are a number of these, but each one is serving quite a few electrical items.  Any unwanted high resistance due to a bad joint will cause voltage drop.  When the horns are used, several amps will flow to ground, the extra voltage drop could therefore be upsetting something else connected to the same ground point.

 

I attach the schematic for the horns, which are powered via a relay driven by the onboard supply control unit.  The Treble Horn H2 grounds via Main Harness Ground connection 5.  The Bass Horn H7 grounds via Main Harness Ground Connection 14, and thence to Ground Point 1, front of right longitudinal member.

 

The horn push operates at low power levels and communicates with the Steering Column Electronics Control Unit via two "Clock Springs".  I think this part is unlikely to give your symptoms, but I include a diagram.

 

Time to check your ground points, which may only be possible by undoing them as any corrosion can be hidden from view.

Hi Austin7

Thanks for the detailed info. 
When I get time I’ll take a look. It maybe nothing, but looking through the small amount of paperwork that came with the car I noticed that a clock spring had been replaced at some point.

Again, thanks for the help

3 hours ago, Paul52 said:

If your battery is at an age where you might be anticipating a replacement in the foreseeable future don't rule it out as a cause of your problem. I've been lurking on this forum for 11 years and seen members tearing their hair out with strange and wonderous problems which all came down to a failing battery - even sometimes when the evidence suggested the battery was fine. I did experience this myself with odd and unrelated things happening when the car got to four or five years old, even though the car started every time without problems. I took the risk on replacing the battery (thinking it wouldn't be money wasted and would cost less than a couple of hours of mechanics time) and everything was back to normal. As Skoda say "Simply Clever" but for owners sometimes "Annoyingly Frustrating". It's only a suggestion if your battery is getting a bit long in the tooth however.

Hi Paul52

I think that I will replace the battery as i have no reference of how old it is. As you say it has no starting issues, but it can’t hurt as it’s not 100% healthy.

23 minutes ago, Dunkf said:

Hi Paul52

I think that I will replace the battery as i have no reference of how old it is. As you say it has no starting issues, but it can’t hurt as it’s not 100% healthy.

Battery manufacture date will be on the battery, if its a VAG battery its on the top month/year ... other makes may vary on location but it will be there somewhere on the battery. 🙂

Edited 30 May, 20242 yr by TruckbusUK
typo

1 hour ago, TruckbusUK said:

Battery manufacture date will be on the battery, if its a VAG battery its on the top month/year ... other makes may vary on location but it will be there somewhere on the battery. 🙂

Hi TruckbusUK

Just checked the date on the battery. It’s Aug 2017 so I’ll definitely change it. 

2 hours ago, Dunkf said:

Hi Paul52

I think that I will replace the battery as i have no reference of how old it is. As you say it has no starting issues, but it can’t hurt as it’s not 100% healthy.

Post deleted as already answered.

On 26/05/2024 at 16:37, Dunkf said:

2014 L&K to 170    [Model: 2009 Yeti Elegance TDI 170]

Can you confirm which car, 2009 Yeti or 2014 Yeti?

 

8 minutes ago, Dunkf said:

Just checked the date on the battery. It’s Aug 2017 so I’ll definitely change it. 

Try fully recharging it with an appropriate charger maintainer first, read and follow the instructions in the car's Owner's Manual and charger's instructions.  Better lower and slower recharging to full than higher and faster recharging to full.

 

12v car battery is the most oversold car part many being replaced unnecessarily or prematurely or very prematurely (7 years wouldn't be so good on a 2009 model at least). 

 

But if you'd still sooner change the battery then best to get the new battery 'coded' in for the sake of speed and at the same time if possible get a full scan tool report on your car and then have all the error codes deleted.

 

Battery manufacturer date isn't fitting date but you'd hope they'd be fairly close but (nothing is certain with s/h cars or any car from the motor trade).

 

Hi

It’s a 2014 L&K TDI 170. I haven’t changed my profile since I changed cars.

when you say coded, could you explain? I’ve heard it mentioned before, but never known what that does. with past cars I’ve just changed the battery

My 2015 Yeti doesn't have stop-start so no coding was required when I replaced the battery last year.  However my wife's 2016 Fabia does have stop-start and the recent new battery did need coding.

Edited 30 May, 20242 yr by DGW

11 hours ago, Dunkf said:

when you say coded, could you explain? I’ve heard it mentioned before, but never known what that does. with past cars I’ve just changed the battery

Dennis has covered it.  The start/stop has a computer program for the battery so battery details are entered, plus it would help VW monitor build and any battery issues under warranty - there was a one time a Recall, when more likely it'd have been the computer program at fault as VW might not have ben as clever as they thought they were with it but as we all know they could be very clever with using computer programs to fiddle the figures when wanted. 😆

 

If you've not got start/stop then it might well be worth fully charging the battery with a charger, unless you have used, abused or neglected the battery too much, or a car fault has done so, you could well see more years out of the battery.  Up to you of course.  Good luck.

 

Hi

I’ll put it on charge tonight, just to see if it makes a difference but I’ll probably change it anyway as it’s a few years old and I don’t know the history as I’ve only had the car since September 

The sooner you can put it on charge and the lower and longer it's on the charge the more chance of getting it fuller and nearer full, overnight and well into tomorrow perhaps.  If you [£TA: missing word]  don't - have the chance to get it fully charged in one go then do the same tomorrow.

 

If you can do check the electrolyte ('water') level of each cell (take no notice of any 'magic eye' ball) sometimes you only need peel back the label(s) on the top to expose the screw tops to the cells which also give you a chance to look at the plates in each cell, often it's an end cell that might look iffy, if so you might be better replacing the battery to be sure of less to do with it.

 

As you don't know the history then I'm with you about changing it to be sure and then you can look after the new battery more and better.

 

Good luck, let us know how you get on.  It may not cure the horn issue but with engine starting and electrical issues (particularly involving the computers) a fully charged battery can help and a low battery can hinder and prevent proper diagnostics proceeding.

 

Edited 31 May, 20242 yr by nta16