[Ovmsdev] OVMS VW e-UP T26 connector

[Michael Balzer]

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:
>>
>> 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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>> OvmsDev at lists.openvehicles.com
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>
>
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-- 
Michael Balzer * Am Rahmen 5 * D-58313 Herdecke
Fon 02330 9104094 * Handy 0176 20698926


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