Thread: Tekonsha Primus iQ on L320 - doesn't detect trailer

What has been done about the vehicle's 2nd trailer parker circuit used by the same pin as the electric brake wire (pin 5 IIRC)? This wire is normally cut behind the left light cluster or just after it then the now cut wire to the plug connected to the brake controller's o/p. I assume that the portable controller provides power on the brake wire whenever the brake lights are activated but the controller may check that the brake wire is not already live before powering the brakes.

The controller probably does a continuity check on the brake wire to earth through the magnet coils but if alive then it would think that the brake wire isn't connected. Can you try driving off to check if the brakes are already applied?

Thanks Graeme. I'll check that out in the morning. No mods to the vehicle wiring at all so if the L320 has an "odd" wiring connection from the factory (as you mention) then perhaps this is doing weird things.
IIRC the "input" side of the controller adaptor harness had the #5 pin not wired - I think the #2 and #5 wires were joined to #2, and #5 was left free. I'll check that after a sleep. Maybe I should remove that double up? Certainly the #5 on the "output" side only had the brake feed from the controller unit and there was nothing from the vehicle on #5.

That sounds OK. Furthermore if a brake controller was used previously then the 2nd tail-light wire must have been cut for that one to work.

If not done already, check that the van's brake wire is on the same pin because #5 wasn't always standard.

The previous owner towed with late model Ford product (never more than a year old). Territorys and Everests and Rangers. They all come standard with a 12-pin flat.
I'll check the van end as well. That's a valid thing I overlooked - you never know what has been done before you and how they made it work. Perhaps they rewired their controller adaptor to suit? After a cuppa helps clear the brain fog I'll have a proper look. Nasty cold and lack of sleep means I'm not quite as sharp as I'd like to be.

Sorry Peter. No idea what that's about...
On the wiring side I think I've found it. The van plug has the brake wire on the 5-pin side (#11). The 7-pin side is empty in that spot (#5). I'll rewire and see how that goes.