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Enable the second fog lamp on a Skoda Yeti.


Great Yeti

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does this reduce the wattage output in any way?

I take it you mean the 2nd lamp, it is running off the cars full voltage thru the relay so no.

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Would you consider making up a kit and selling it to fellow Yeti owners?

Hi All  :hi:

 

I would have loved doing that for you but personal circumstances prevent me from doing it.

 

Really Guys, It is VERY simple. You can just "string" it together with cable between the components, suitably insulated of course. No need to put it in a box, just wrap or "heat shrink" the whole thing. It's very small.

 

Really sorry I cannot do it for you but I am VERY happy to assist in ANY way I can.....................Tony

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  • 2 weeks later...

A couple of years ago I tapped onto the canbus outputs to the bulbs to drive my trailer socket / bike rack board. I also used the same method to bring on line the nearside fog light.

I did mine similar to your circuit diagram, but on the input stage to my interface, I used opto isolators, so even if you put 240 volts or a high voltage spike onto the trailer socket, there is a minimum of 5000 volts isolation between the socket and the canbus, so no back emf spikes could interfere with the circuit.

There was a lot of controversy at the time, you can damage the can bus... no longer under warranty etc etc, this is what made me move from a simple transistor driven circuit to an opto isolated unit. I used the darlington driver version of the opto isolator family to reduce the loading on the bulb circuit, after all, the circuit is driving nearly 2 amps +/- bulb tolerances, as you say, an extra mA will not be noticed as it's a resistive load. With my circuit, there is no leakage to the second foglight or trailer bulbs, under any fault condition.

I support your circuit, it will work fine for the second foglight, it's just that I took it one step further as I was connecting to a trailer socket, with often unknown wiring or reliability if it's someone else's lighting board.

Richard

Edited by rustic
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  • 2 months later...
On 14/01/2017 at 16:16, rustic said:

A couple of years ago I tapped onto the canbus outputs to the bulbs to drive my trailer socket / bike rack board. I also used the same method to bring on line the nearside fog light.

I did mine similar to your circuit diagram, but on the input stage to my interface, I used opto isolators, so even if you put 240 volts or a high voltage spike onto the trailer socket, there is a minimum of 5000 volts isolation between the socket and the canbus, so no back emf spikes could interfere with the circuit.

There was a lot of controversy at the time, you can damage the can bus... no longer under warranty etc etc, this is what made me move from a simple transistor driven circuit to an opto isolated unit. I used the darlington driver version of the opto isolator family to reduce the loading on the bulb circuit, after all, the circuit is driving nearly 2 amps +/- bulb tolerances, as you say, an extra mA will not be noticed as it's a resistive load. With my circuit, there is no leakage to the second foglight or trailer bulbs, under any fault condition.

I support your circuit, it will work fine for the second foglight, it's just that I took it one step further as I was connecting to a trailer socket, with often unknown wiring or reliability if it's someone else's lighting board.

Richard

Thankyou for the information, that's great advice.    jon.

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  • 9 months later...
1 hour ago, davetom said:

Hi Tony

How did you get the Rear DRL'S to work - I have a Yeti Adventure 4x4 and would love to have these lights working! - Dave

 

Not sure how Tony did it but the ‘correct’ way needs either the dealer or someone with VCP to code them (VCDS cannot do this)

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On 1/13/2018 at 16:43, davetom said:

Hi Tony

How did you get the Rear DRL'S to work - I have a Yeti Adventure 4x4 and would love to have these lights working! - Dave

Hi! As Gizmo correctly says below. It's a two minute job by a dealer (who knows what they are doing!) or someone with VCP. Our dealer was only to happy to do it for me Free of Charge when he had our Yeti hooked up to their system. We also had it done on our first [2010] Yeti (different dealership), again FOC it is so simple........Tony

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  • 4 years later...

Hi Everyone. A quick update to this somewhat rather ancient thread…..

 

Recently some members have contacted me to let me know that some of the links to PDF Guides that I did some time ago for the Škoda (Technical) Guides section have stopped working! It would appear that Google Sites, where the original guides were saved for viewing online, last year changed the way it operates, and that some of the links to the PDF guides are no longer operative. It’s all a bit haphazard as about 50% still work, but the remainder don’t. So if this has caused you any inconvenience I do sincerely apologise. 

Things change and as time has passed, some of the information may seem a little dated. However, so are our vehicles, but some of the information is still relevant and may help others. I think the best way forward for these to be enabled for viewing is to upload the relevant files directly to Briskoda, where I am sure they will be safe for future reference. So here, attached to this post, is the PDF Guide that this thread refers to. Should you come across any others (of mine) please let me know and I will do my best to update them.

Hope this helps………..Stay safe & happy motoring………Tony

PDF Files Attached:

1 - Enabling the Second Fog Lamp - Guide (PDF)

2 - Second Fog Lamp - Circuit (PDF)

Enabling the Second Fog Lamp - Guide.pdf Second Fog Lamp - Circuit.pdf

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Is it legal to have 2 rear high intensity fog lamps? I thought only one so they are not mistaken for brake lights.

From the MOT manual.

Front and rear fog lamps

Presence, condition and operation

The Tester will inspect:

  • front fog lamps fitted to vehicles first used on or after 1 March 2018
  • the 1 rear fog lamp which must be fitted to the centre or offside of vehicles first used on or after 1 April 1980
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They are testing what is presented to them to the minimum requirement.

 

Lots of vehicles in the UK have 2 rear fog lights. 

Both working is OK as long as matching, but if the nearside one was to have stopped working then no worried if the offside one is. 

 

The IVA Inspection in the UK which Imported Cars or Radically Modified will be required to comply with.

Stricter than any UK MOT Inspection. 

Screenshot 2022-02-13 11.14.36.png

Edited by roottoot
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  • 3 weeks later...

When I had my first Fabia in 2002 and later on, an Octavia, all I did to get the second rear foglight to work was to run a length of cable from the working light through the boot under the carpet, to the second light and connect it to the bulb holder in the relevant place for the second filament. I was given the cable with the correct connectors by my local main dealer. It all worked fine and no reprogramming or whatever was ever done to my knowledge. Admittedly the cars were 2002 and 2004 so things may have changed since then.

 

Chris

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I was looking carefully at mine & the options on VCDS last week as I need a Controle Technique, that is still the only viable solution other than my changing the coding of the body control module to say that the car is LHD instead of RHD and that is likely to screw up loads of other things.

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stephmobile

J.R.

b1ackb1rd

 

Hi Guys,

I am so sorry to bring bad news but I am afraid that what you have been told or are suggesting is either not possible or potentially hazardous. Please allow me to explain:

Historical information: The Yeti as supplied to the U.K. market (U.K. Spec) was not fitted with a cable from the BCM (Body Control Module) to the nearside rear cluster despite the cluster containing all that is required, including a bulb and reflector that would allow the n/s fog light to illuminate.

Yes, I am aware that some other models, Octavia etc were fitted with the cable, and that it required a simple recoding (VCDS etc) for it to operate, but this is not the case here. In years past, a lot of to-ing and fro-ing went on by some Briskoda members telling others they had done it on their Škoda, but all this did / does is muddy the waters as regards this information. The YETI does NOT have the cable in situ that would allow this. Go ahead and check your Yeti n/s cluster! You are one cable short. On checking the o/s you will find there is one more cable than on the n/s. That's the Fog Lamp feed.

 

Some Technical Info:

Unlike vehicles of yesteryear, just about all vehicles produced since around 2010 operate a Can Bus system. This system operates by data signals being sent to a series of BCMs, Body Control Modules. A BCM is a small electronic unit (brain) which uses several integrated circuits to actuate several facilities connected to it, eg: All “Driving” lights; Head lights, Fog Lights, Break Lights, Radio, Sat-Nav, and ALL safety-related devices etc. plus a whole load of electrically operated equipment in the car with just about all engine and transmission components being monitored and adjusted as you drive. Almost everything on the car is monitored by the Can Bus  system; Can Bus is just a pair of twisted small wires that run all over the car in a ring main type manner that carry data instructions to all the BCMs, engine management systems etc

Once of a day, a simple switch allowed power to flow to a piece of equipment. No longer! The switch today, if indeed there still is one as many functions are carried out by touch screen, simply sends a data pulse (signal) to the BCM to turn on the appropriate i.c. This is what you have in your Yetis and should you overload these i.c.'s, you burn out those circuits and a new BCM plus recoding is required. That is assuming that no further damage was caused by the burning out of the unit, (The car itself!).
BCMs are expensive and require specialist equipment (VCDS etc) and a pretty good level of knowledge to re-program them. Overload a BCM at your peril and prepare for a good sized bill!

 

To give some idea of what is and is not possible / advisable:

Q 1: Additional Cable. People wondered some years ago and now, whether they could just run an additional cable from o/s to n/s and connect it to the n/s cluster and thus have two working fog lamps.

Ans 1: VERY inadvisable! Powering up two Fog lamps by using this method would probably seriously overload the circuits and blow the BCM. A single fog lamp is a 12v 21w bulb = 1.75amps. Two would be 3.5 Amps, a doubling in capacity for an i.c. and the associated p.c.b. tracks to handle. The i.c. and / or the tracks will highly likely burn out eventually, if not immediately! Imagine if you will, a scenario where you are driving down a motorway one winter’s evening in dense fog and with your two rear fog lights on when the BCM fails as a result of the overload. You now have no functioning rear lights whatsoever! Side, brake, indicator & fog lamps are all out!  With luck the front headlamps lamps may still be working if the blowing of one BCM doesn’t take out another. I certainly would not risk my family in this way & I’m sure you would not either.

Ans 2: It would be possible to run the cable as described BUT remove the connection to the o/s lamp. This will ensure that only the same current flows through the BCM by virtue of still having only one lamp lit. Great care would be needed to ensure that only one lamp can be lit by ensuring the o/s is completely disconnected and isolated.

Ans 3: For our friends that live or travel abroad in the EU such as France, Germany etc with a U.K. spec Yeti, a different modification would possibly be better.
EG: Cut the Fog Light wire before it terminates in the o/s cluster and connect it to a “single pole, double throw” switch. Connect the remaining wire to the o/s cluster and then run a new cable to the n/s cluster and connect this to the lamp and switch also. By doing this, you can activate either the n/s or o/s lamp but not both. By doing this your car will be either E.U. or U.K. compliant just by operating the switch for the desired side to illuminate.

It’s really easy to do and a suitable switch is easily placed adjacent to the o/s cluster. If you obtain a round (easy to fit, just use a drill for the hole cut out!), black SPDT (Single Pole Double Throw) round switch. It will readily fit into the adjacent black plastic trim and be almost invisible. Anyone who fancies doing this for themselves and needs help, please PM me with your E-mail address and I will help if I can. I have done this for friends and can tell you where to obtain a switch and just how to fit it. The cost is minimal, just a couple of metres of cable and the switch come to about £3. You also need a small (similar to but not a) “spade” type connector to allow you to connect into the n/s wiring loom connector. There is a picture of the "spade" & connector in the guide but you may be able to blag one out of a Škoda technician or a friendly auto electrician. I got one out of a scrap Škoda wiring loom from a breakers yard; it’s a very common VAG part.

 

Q 2: Reprogramming via VCDS etc for n/s operation.

Ans: From my above comments at the beginning regarding the absence of any connection to the n/s cluster, you will clearly see that even though the VCDS may allow a reprogramming of the BCM from o/s to n/s operation, it will not work without the additional wiring, and for the reasons stated, piggy backing a new wire onto the old or direct to the BCM is seriously ill advised.

 

Having two working rear fog lights:

If you look at the circuit that I designed (see post No:13 - 11 Feb 2022), you will see a very simple, easily constructed circuit that avoids using the BCM to power up the n/s fog light but yet has the ability to use the o/s to provide a signal to this circuit that will turn the n/s fog lamp on with almost zero loading to the BCM and Can Bus. In operation the trigger signal from the o/s lamp uses less than 1000th of an amp (0.001mA). This is so small that the Can Bus and BCM cannot see this and therefore suffer no effect whatsoever. All that is needed is the circuit itself and a wire running from the circuit to the n/s fog lamp. My circuit design is very simple, easy to manufacture and inexpensive. Someone else would possibly design it slightly differently and utilise different components but to the same effect. I chose the “Keep It Simple” (KIS) method in the hope that others would understand the circuit more easily and have a go for themselves as the “bits” are all easily obtainable. I know it’s reliable as it is still operating without any problems on my original 2010 Yeti, and a couple of old Briskoda friends are still using theirs 10 plus years on. I suspect there are more out there…..

 

I’m really am so sorry to bring you the information that you were given previously is incorrect, I wish it was otherwise! A few years ago this was a real hot topic in the Yeti section and contrary to much of the advice regarding reprogramming etc. given by others who had Škodas, (BUT NOT Yetis); it left a good many disappointed. That’s why I came up with the circuit that does not load the BCM or affect the Can Bus but will safely give you two working Rear Fogs.

I hope this helps you in your quest for activating the second fog light or in having the ability to swop o/s to n/s operation for use of U.K. spec Yetis abroad. My offer of assistance is genuine, if I can help, I will.

Happy motoring and stay safe…..Tony

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5 hours ago, Great Yeti said:

Ans 1: VERY inadvisable! Powering up two Fog lamps by using this method would probably seriously overload the circuits and blow the BCM. A single fog lamp is a 12v 21w bulb = 1.75amps. Two would be 3.5 Amps, a doubling in capacity for an i.c. and the associated p.c.b. tracks to handle. The i.c. and / or the tracks will highly likely burn out eventually, if not immediately! Imagine if you will, a scenario where you are driving down a motorway one winter’s evening in dense fog and with your two rear fog lights on when the BCM fails as a result of the overload. You now have no functioning rear lights whatsoever! Side, brake, indicator & fog lamps are all out!  With luck the front headlamps lamps may still be working if the blowing of one BCM doesn’t take out another. I certainly would not risk my family in this way & I’m sure you would not either.

A lovely tale but it would not happen, the bulb circuits are monitored to protect the output transistors of the BCM, iff too high or too low a wattage bulb is detected (a higher or lower volt drop than the specification) then that outputs from the BCM will be shut down, it is why people fitting LED bulbs, incorrect wattage bulbs etc have problems and why the intermittent contact from a standard bulb fitted to the DRL's of a facelift Octavia 2 will result in the bulb never illuminating, my BCM can be programmed for LED bulbs.

 

A transistor could be overloaded, reverse biasing is what usually does for them, but it wont affect the other outputs and the PCB track will not burn out.

 

If people shunt one output to both rear foglights and the circuit protection does not cut in then the IC can handle the current, I would remove the RH bulb if running a shunt wire to my LH foglight, I'm not even going to bother this time, my CT tester is a sensible guy.

 

You methods of the change over switch and the relay or transistor circuit would work well, years back when I enjoyed playing with and learning electronics I would have done the same, now life is too short for me to be concerned what side my fog light is illuminated.

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