BilTechnik

Possibly, I assume the clocks will use any speed signal they get. Really nice retro diagram in that SSP. It was just a passing sentance, rather than a chapter as I remember. Writing the bit of code to utilise the hardware they already have and provide a subtle improvement to the customer would be very cheap for them to implement for a good reward. When I tried it, the fuel was near reserve, and it fluctuates enough that you can turn the fuel light on/off, along with the acompanying beep, with fairly normal driving. So it would be very annoying if they didn't smooth it. As to why they don't apply the strong smooth costantly, I cannot comment. I guess this is probaly only marginally more diffuclt, and is tangible better.

So this started a few weeks ago when my Fabia started leaking cooling. After a lot of searching around, I found it coming from the bulkhead where the heater matrix connects. There are two alloy pipes that go into the matrix, with a braket attached at the top. Except in my case, the bracket was no longer attaced (what 200k miles does to aluminium). Initially I thought that heater matrix would have cracked too (not just damaged O-rings) , so I was preparing to swap that. I started looking for a new matrix, and while doing so came accross a PTC heater for £30. An eBay offer later and I had an original Skoda PTC for £15, including clips and bottom housing! See eBay pictures below. I did confirm it was an option, and the part codes were right for my car before purchasing, but that was as far as I got. As I understand this is the earlier version, that has been superceeded twice to get to the version that fits in the Polo 6R. The following link is an excellent page that shows the newer style, and has some good wiring diagrams, albiet wrong for a Fabia. https://polo.blue/2018/09/02/ptc-retrofit/ Another eBay best offer later, this time of £20, resulting in a 120 amp alternator (thanks @varooom and @Breezy_Pete for the info). Hopefully this is a direct fit. My car has a 90 amp alternator as standard, I will try with that first and log the load factor with VCDS to see if it's viable to not upgrade. You can also get a 110 amp version for a similar price. Now for the bits from the dealer, this is the expensive bit. I'm going for 100% OEM, so you could omit these and go for generic parts if you want. 6Q0937617B Fuse holder, will add price later but around £10 N01713120 40 amp fuses to go in said holder, you need 3 - Around £1.50 each 1J0972753 - Plug to connect to the PTC heater - Around £10 4B0937527A - Relay plate. You need two. These are around £14 from a dealer which I refuse to pay, so I'll be getting used. It can be any part number, justs needs to fit in the relay frame and support large pin (will confirm dimension) relays. As for the pins, I'll be ordering them from TE connectivity so I can crimp them to my own wire, and avoid having to splice to repair wire. The OEM relays are number 644 and 645. I will instead be using 70 amp rated Panasonic items as they are far cheaper, and new. Will update once everything arrives, and once I have details on the pins finalised.

This is going to be a guide of how to fit the PTC heater option using the OEM control system and OEM parts. Its going to be a work in progess/follow along style, but I'll edit this post when its complete with all the information you need. With currnent eBay and dealer prices, the whole job costs less than £100 and could be easily completed in a weekend. First thanks to @Crocket@piggoy@Breezy_Pete@jacissmiling for all the effort on the original thread

Yeah several people online have hadt when their ABS module has broken. Thanks for confirming Pete Yes, ABS transmits the speed data on CAN, for your speedo and such as Pete mentions. There's no need for the Airbag controller to expose information about acceleration, so it doesn't. The processing for the "calculated acceleration" happens in the cluster. I didn't expect this to cause so much discussion, so I wasn't clear in my original post. The cluster is estimating if you're accelerating or breaking, based on the rate of change of speed, and when doing so, slows down/stops its reading of the fuel sender to prevent erratic readings. The position of the sender in the tank is irrelvant in this case. Ideally VW would put the sensor in the centre of fluid, and the tank would be a hemisphere, and fuel wouldn't splash, that way you'd have a perfect reading regardless. But they can't do that obviously. If they have put the sensor in at 90 degrees to the direction of travel, I would assume this has been done to get closer to that perfect scenario of a central float. The sender is on the far left/right of the tank to begin with, so cornering forces are already going to have a much greater affect than acceleration of deceleration. By pointing the float inwards, you make little difference to the fore/aft position but you get much closer to the centre, thus minimising the cornering affects. It could also simply be packaging. To correct my previous statement, the Fabia dash cannot compensate for steering angle as there is no real accelerometer data, nor is there a steering angle sensor as these cars didn't come with ESP. Golf MK4 on the other hand, that may be different. I did find it in an SSP a while ago Pete (And confirmed by taking the fuse out), will try and find it

Thanks for assistance everyone

£20 later and I have a 120 amp alternator. Will start a new thread as a guide

Cheers both. Yeah checked the fuse is 175 as mentioned, and the cabin fuse is 110 amp regardless of PTC/no PTC. Wire gauge is the same too. Will double check the alternator wire but I think it’s bigger of the too. At idle (no lights, no steering, no fans, just after startup) I have around 30% load in VCDS, so theoretically 60 amps spare which will be tight. Will make to sure to get some logs and see how bad it is. Are those alternators on any other models @varooom? Trying to get this cheap as possible

And a constant warning buzzer as I remember? It’s possible you have a different ABS system or have removed a different fuse

Do have a ABS warning light with the fuse removed?

05 Fabia 1.4 TDI. Will try with the 90 Amp alternator to begin with but I suspect it will be tight/limit the full power mode of the heater. Do you know what cars had the 110 Amp alternator (or bigger)? Seem to be a bit of a rare beast on eBay

Take your ABS fuse and go for a quick drive. You’ll notice a difference immediately, especially if your fuel is quite low. Measuring acceleration with wheel speed rate of change is trivial. The gauge is damped but only slightly. If you accelerate or break the averaging time is increased to hide the affect of the fuel moving around. The airbag sensor isn’t used as acceleration data is broadcast on CAN. I wouldn’t be surprised however if the instruments also increase averaging time based on steering angle, although I haven’t tested that

Yeah I was confused by that a first, it’s deceiving because non of the wires on that diagram exist in that way on my car, at the end of the wiring diagram document there actually a page which shows the correct wires, and that matches the polo setup. Surprised me that the Polo uses an “old” Skoda system, though it was normally the other way/equivalent

Ahh whoops sorry I meant F268. The PTC enable switch/line in the heater controls

Will do I think the wiring diagrams were the misleading bit last time, Fabia’s, at least with air con, come pre wired on the engine bay side for it. They also the HVAC control system from a Polo 6R ( or I guess the Polo 6R using the controls from the Fabia) so the control is CAN based, rather than using that F248 wire. Glad it worked out on yours, was a bit worried when I saw the posts about the heat output being very low

As mentioned there is a channel in VCDS, that vortex guide is good. It normally doesn’t need doing unless the car has had a fuel sender in the past or the sender has some how got damaged. Normally the fabia range meter and fuel gauge are very pessimistic for obvious reasons. Fun fact: Fabia’s actually use the ABS controller to measure the vehicle acceleration/deceleration to compensate for fuel slosh in the tank

Apologies for the terrible thread revival, but I've just ordered all the parts to make this work as an OEM system. Is there still enough intrested for it to be worth me making a guide?

Had a Fabia MK1 for many years, seeing how long it can go and having some fun with it along the way