My 2 cents:
I think tapping into wires (variant 2 / footwell
panel) isn't something we should suggest / encourage
users to do.
A regular user is perfectly capable of unmounting the
passenger seat and plugging in prefabricated
connectors. That also is easily reversible, and using
the original antennas for the OVMS is really neat as
well.
So I'd vote for variant 1 (combined with OBD), with a
long cable to mount the OVMS module in the front left
near the OBD connector (i.e. not replacing the OCU
under the passenger seat), and the kit for that
could/should include the Fakra antenna plug/adapter
with antenna cables of the appropriate length to
connect to the module in the front.
@Mark: for clarification, this image shows a very
short T26 connection meant to place the OVMS under the
passenger seat near the T26 connector, replacing the
OCU:
This does not apply when mounting the module in the
front near the OBD port.
Taking +12V from the OBD port, the T26 connection
cable then only needs to connect GND and CAN-L, CAN-H
of the T26 connector:
This image shows the vehicle side of the T26
connector, i.e. the OVMS cable needs to be plugged
into that.
It would be nice if the OVMS plug could also be
secured by using the white lock lever shown, that's
what Chris intends by using some original T26 part for
this. Maybe there are compatible connectors available,
but other ways to secure the connection would also be
OK.
Can't help with the cable lengths needed for a proper
installation, I still haven't done that connection
other than by a flying CAT5 cable for re-engineering…
Regards,
Michael
Am 26.11.25 um 08:15
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:
If there anybody here knowledgeable about this,
that could help specify the cable exactly? Things
like:
- Exact T26 connector
- Length of each cable segment
- Cable wire type
- 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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