[Ovmsdev] OVMS VW e-UP T26 connector

[Chris van der Meijden]

Oh and about the TCU ...

With the footwell cable you can keep the TCU in the car. (powerless by
pulling the fuse).

There are always questions about removing the TCU and warranty. I
always communicated the replacement of the TCU with OVMS openly and I
never had any issues with warranty and service at the VW dealer. But I
don't know how the legal side on that topic really is.

Am Mittwoch, dem 26.11.2025 um 08:15 +0100 schrieb Chris van der
Meijden via OvmsDev:
> Hi Mark,
> 
> as I started the e-Up OVMS project years ago my first approach was
> the T26 cable. The reason for that more complicated cable was that
> with the direct connection to CAN3, I was able to get write access
> for i.e. climate control.
> 
> My way to do so was replacing the VW TCU under the passenger seat and
> connect to the VW T26 connector there (hence the name T26). 
> 
> As the project developed the direct ODB access was added by other
> very capable developers to gain more data from the car. So we ended
> up with 4 cables. T26 alone, ODB alone, ODB + T26 under the passenger
> seat, ODB + T26 at the passenger footwell panel.
> 
> T26 alone and ODB alone have only historical value, so there needs to
> be a decission, if you want to make the hybrid cable for under the
> passenger seat or at the passenger footwell panel.
> 
> The advantage of the "under the seat" cable is, that you can use the
> GPS and GSM antenna of the car. Disavantage is, the you have to
> struggle with the seat. The "footwell" cable is much easier to
> install, but OVMS will need extra antennas for GPS and GSM.
> 
> I would suggest, that the decission about what cable to make should
> be discussed here briefly first.
> 
> Then someone will probably be able to provide the length of the
> cable.
> 
> Information on the connector, wire type and pinouts are in the
> documentation. The connector is a workaround as we were not able to
> find the original female T26 plug. But perhaps things has changed and
> somebody has more information on that now.
> 
> Hope this is of some help.
> 
> Regards
> 
> Chris 
> 
> Am Mittwoch, dem 26.11.2025 um 10:49 +0800 schrieb Mark Webb-Johnson
> via OvmsDev:
> > We’ve had some enquiries regarding making a standard OVMS cable T26
> > for VW eUP, Skoda E IV, and Seat MII electric.
> > 
> > From my understanding, the cable is variant 1 described here:
> > 
> > https://docs.openvehicles.com/en/latest/components/vehicle_vweup/docs/index.html
> > https://docs.openvehicles.com/en/latest/components/vehicle_vweup/docs/index_t26.html
> > 
> > If there anybody here knowledgeable about this, that could help
> > specify the cable exactly? Things like:
> > 
> > 1. Exact T26 connector
> > 2. Length of each cable segment
> > 3. Cable wire type
> > 4. Pinouts
> > 
> > Preferable somebody who has already done it and can document
> > exactly what they have.
> > 
> > Also presumably this requires unplugging the existing OCU, and what
> > is the impact of that?
> > 
> > Regards, Mark.
> > 
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