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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