Hi all.

 

Hoping you are able to help me work out how the mk1 fabia VRS works in terms of the speedo (as there is no speed sensor on the gearbox). Is there a dedicated speed wire which comes from the abs unit to give a clock signal?

 

The reason i ask is i have swapped a VRS engine and ecu into an arosa 1.4tdi shell. The wiring was simple to get it up and running, but i am left with a bit of an odd fuel gauge and no speed signal.

 

The fabia ecu communicates fine with the clocks, as i can test them in VCDS/vagcom - and make them sweep as needed.

 

The arosa does have ABS, so i was hoping there is a way to get a working speed signal as there would be on the fabia vrs?

 

I have looked on elsawin, and can see both ecus share the same pin (20) to the clocks - however this is the 'E.speedometer output'. The input on the arosa, is from the 3 pin plug on the gearbox, and this runs directly to the clocks with the following wires- Blue&White / Brown&White / Black. I believe two wires are 12v and earth, leaving the single signal wire White&Blue.

 

Can this white and blue be tapped into anywhere on the ABS side of things to work?

I think in Mk1 Fabia vRS the vehicle speed is communicated from ABS ECU to Instrument cluster by CAN message rather than a wire.

Not sure how that helps, if at all.

 

 

1 minute ago, Wino said:

I think in Mk1 Fabia vRS the vehicle speed is communicated from ABS ECU to Instrument cluster by CAN message rather than a wire.

Not sure how that helps, if at all.

 

 

 

Thank you. I did look into the wiring and the clocks i have are connected to can H and can L, which is also connected to ABS on the arosa (so wrongly assumed they should work before testing haha).

 

The only work around i can see is to use a GPS to VSS box, but its a bit of a bodge way of doing it. I may have to look at the fabia clocks to see if its something internal to them that converts the can signal :(

 

Having a nightmare with it haha. 

Are you sure there isn't a blanked off hole in the new gearbox where you can retrofit a speed sensor?

1 hour ago, mad-modz said:

its something internal to them that converts the can signal :(

Well the clocks (in a Fabia is where that CAN signal gets 'understood' and converted into the speedo needle position. 

Not sure where else the speed signal is utilised, if anywhere.

 

Just clarify please, which bits in the car at the moment are from Fabia, and which are still original to the Arosa?

Engine = Fabia?

Gearbox = ?

ABS ECU = Arosa?

Cluster = ??

1 hour ago, Wino said:

Well the clocks (in a Fabia is where that CAN signal gets 'understood' and converted into the speedo needle position. 

Not sure where else the speed signal is utilised, if anywhere.

 

Just clarify please, which bits in the car at the moment are from Fabia, and which are still original to the Arosa?

Engine = Fabia?

Gearbox = ?

ABS ECU = Arosa?

Cluster = ??

 

Thanks for the reply.

 

Engine and gearbox are fabia - ASZ engine / oa8 6 speed gearbox.

Abs ECU is arosa

Cluster is arosa, but also tried lupo gti with the same outcome.

 

The wiring loom is arosa TDI - it is pretty much the same as the fabia loom bar needing an injector line swapped and another adding (all the communication pins are the same inc can H & L)

 

The only difference is the arosa loom has the speed sensor plug still, where as the fabia doesn't. (all other engine related plugs, plug into the engine and work as they should). Tracing the 'information' wire back from the original arosa speed sensor plug, i can determine it goes directly back to the clocks (not via ecu).

 

I know that the ABS is communicating with the ECU and giving a MPH signal, as i can live read this information using VCDS with a slow drive down the road.

 

Its just then working out how to get the MPH reading to the clocks.

 

I was unsure if there was somewhere i could steal this pulsed signal from (seeing as mph does show in vcds/vagcom)....