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Discussion Starter · #1 ·
Dear Members,

Hello from Australia. I hope someone can help with the installation of a Tekonsha Primus brake controller. The controller has 4 wires, black for constant 12V+, white for ground (-) and Blue for the signal to the trailer. My problem is the Red one, that is meant to go to the 'cold side' of the brake switch. I have managed to install everything but the red wire. My V90CC (2019 model) has 2 switches attached to the brake pedal (one on the side with a black plug and one 'head on' with a yellow plug) and I have problems to identify the 'cold' brake switch wire. Has anyone done this before and is able to assist? Thank you in advance. Regards:confused:
 

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Dear Members,

Hello from Australia. I hope someone can help with the installation of a Tekonsha Primus brake controller. The controller has 4 wires, black for constant 12V+, white for ground (-) and Blue for the signal to the trailer. My problem is the Red one, that is meant to go to the 'cold side' of the brake switch. I have managed to install everything but the red wire. My V90CC (2019 model) has 2 switches attached to the brake pedal (one on the side with a black plug and one 'head on' with a yellow plug) and I have problems to identify the 'cold' brake switch wire. Has anyone done this before and is able to assist? Thank you in advance. Regards:confused:
It would be the wire that shows power only when the brake is applied.
Don't know color.
 

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Discussion Starter · #3 ·
It would be the wire that shows power only when the brake is applied.
Don't know color.
Thank you, Gruendig.

Unfortunately, that is the problem. I find the constant 12V+ on the break switch plug but none of the other 2 wires changes to 12V+ on pressing the break pedal. I went onto the Tekonsha website and they state that the Volvo does not have a dedicated plug for a break controller harness and that the controller needs to be hardwired, which is exactly what I am trying to do. Any thoughts? Anyone with experience in this regard or should I just take it to an auto-electrician? It's not about the money, it is a challenge!
 

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Did you ask the dealer about that? How do you tow with a V90CC and make the connection to the brake "on" system. It might be a software signal and not a simple on/off.
 
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