Primus IQ Brake Controller Wiring Functions

Question

Question:

can you get me a wiring diagram for Primus IQ brake controller?

asked by: Dan

0

Expert Reply:

The Primus IQ # TK90160 doesn't have instructions that come with a wiring diagram, but we have a picture/diagram on our site that shows which wires are connected to which functions on your vehicle. I attached the diagram for you to view, the wires will be connected as follows:

White - Ground
Black - 12V Power
Blue - To 7-Way at rear of vehicle
Red - Cold side of stop light switch

If you are needing a new pigtail for your Primus IQ it is part # 7894. This same harness will work with most Tekonsha and Draw-Tite brake controllers.

expert reply by: Jon G

0

click to enlarge

Miles F.

2/26/2025

Thank you for providing the wiring picture diagram for the Primus IQ brake controller. Looking at the wiring picture diagram, please confirm if the "Ground (-) White" cable at the "Brake Control" going to the battery -ve terminal is purely the ground for the controller internal circuit (i.e. very low amp draw). If so: 1) Does this "Ground (-) White" cable need to be connected directly to the battery -ve terminal OR can it connect to a ground bus bar at the front of the vehicle?; 2) What should the cable AWG size be for this "Ground (-) White" cable from the brake controller if extra cable is required?; 3) If, therefore, the Ground cable from the trailer connector is for the Electric Brakes magnet circuit (as well as the lighting circuits) what should the cable AWG size be for this ground cable at the trailer and vehicle side of the 7-way connector? Thank you and bless you!

Reply

Jon G.

2/27/2025

@MilesF Either of those options will work. We always use 10 Gauge Wire # 10-1-1 for the ground. If you're needing to run both power and ground to the battery, then I recommend using the 2 Wire 10 Gauge Kit # 10-2-1 instead.

Reply

Miles F.

2/27/2025

@JonG Thank you Jon - GOD BLESS you for your help. ONE MORE question: With a motorhome, there is approximately 35-40 feet from the dash mounted electric brake controller to the trailer hitch hookup. What AWG should the +ve electric brake output cable extension be? is 10AWG also adequate for this cable purpose and length? THNAK YOU, Bless you!!

Reply

Jon G.

2/27/2025

@MilesF You can use lower gauge (thicker) wire if you want, but from our experience a brake controller can't put out more power than 10 Gauge can handle so using thicker wire wouldn't really give you any kind of advantage. Happy to help out!

Reply

Miles F.

3/10/2025

@JonG Hi Jon, ISSUE: Class A motorhome on a 2002/2003 Ford Chassis (which I think is a Ford E-550) WITHOUT a tow package configured for a trailer with electric brakes and how to connect the red “STOPLIGHT” cable on the Tekonsha Primus IQ harness. NOTE: I am an electrician with knowledge on 12v systems so your answer can be technical. The motorhome manual does not mention a tow package for a trailer with electric brakes and I cannot find any under dash plug for this). HOWEVER, there is a factory fitted trailer hitch 6 pin connector BUT only configured for trailer lighting. So I got the Tekonsha Primus IQ which comes with a harness with bare wires that allows me to wire in everything myself. I need to know what to splice the Tekonsha Primus IQ harness RED “STOPLIGHT” cable to - with THIS following issue: The Tekonsha Primus IQ brake controller box contained a warning leaflet which warns of older Fords where the brake pedal switch has a red with green stripe cable which is ONLY hot when the brake pedal is depressed AND when pedal is NOT depressed it goes directly to ground. It states that the red “STOPLIGHT” cable on the Tekonsha Primus IQ harness must NOT be connected to that red with green stripe cable as it will blow the brake controller when “Manual” control is selected. SO, it states to splice to the light green cable on the brake pedal switch instead. However, on this motorhome there is no red with green stripe cable. However, it DOES have the light green cable it states to use instead BUT this cable IS the one that is hot when the brake pedal is depressed, and WHEN pedal is not depressed it goes directly to ground. So surely I cannot use that light green cable suggested either for the same reason. There are 4 cables in total on the brake switch as follows: 1. The above mentioned light green cable: brake pedal depressed = HOT; brake pedal NOT depressed = directly to GROUND 2. Light green with red stripe: HOT all the time (obviously the 12v +ve cable to the switch). 3. Blue with black stripe: HOT all the time (possibly to do with cruise control?) 4. Black with blue stripe: GROUND all the time I then checked the motorhome hitch receptacle connector and discovered that the 2 pins dedicated to the stop (brake) lights are ALSO: brake pedal depressed = HOT; brake pedal NOT depressed = directly to GROUND. So what do I splice/connect the Primus IQ harness RED “STOPLIGHT” cable to where brake pedal depressed = HOT; brake pedal NOT depressed = OPEN CIRCUIT? I pray this all makes sense and that you have the miracle answer. Thank you for all your help.

Reply

See All (8) Replies to Miles F. ∨

George

5/5/2025

In looking at this diagram, the black wire goes from the brake control to the positive battery and then from the positive battery to the trailer connector.I thought the power from the brake controller powered the brakes via the blue brake wire.

Reply

Jon G.

5/6/2025

@George Good question. Those are actually 2 different wires; one goes from the battery to the brake controller for power, and the other goes from the battery to the 7-Way connector for the 12V power. The blue wire from the brake controller will send out power from the controller out to the 7-Way and on to the trailer brakes like you mentioned.

Reply

Answer 1

Hey Steve, congrats on the new truck! The Lomax Stance Hard Tonneau Cover - Folding item #LOM53WR weighs 80 lbs. This cover fits the 2026 Nissan Frontier with a 5' long bed. It's compatible with or without the Utili-Track System. I really…

view full answer...

Answer 2

Hey Bill, You can absolutely use your Primus IQ on your 2023 Ford Ranger! The installation will be a bit different, since there is not a plug and play adapter for your vehicle it will need to be spliced in. If you do not have the universal harness it…

view full answer...

Answer 3

If your Husky Brute Electric Trailer Jack is only making a clicking noise and you have checked the power source there are a couple of other issues that may be occurring. Start by checking your ground connection to ensure it is secured to a clean,…

view full answer...

Answer 4

For your 2024 Nissan Frontier I recommend the Redarc Tow-Pro Liberty Brake Controller #RED24FR. I like the Liberty because it is simple, reliable, and looks great in any vehicle. The main unit installs behind the dash, so only the control knob will…

view full answer...

Answer 5

Hey Miles, thanks for reaching out! You'll need the TruRyde Electric Trailer Brakes #TRU36FR along with 2 of the Easy Grease Trailer Hub and Drum Assembly #AKHD-545-35-EZ-K in order to get your tow dolly equipped with electric braking…

view full answer...

Answer 6

Yes, it is possible to install a Tekonsha brake controller like the Tekonsha Primus IQ Trailer Brake Controller part #TK90160 which is what I recommend on a 24 volt system. In order to do so you will need to obtain a 24 volt relay from your local…

view full answer...

Answer 7

The Universal Mounting Panel for Redarc Tow-Pro Trailer Brake Controller Control Knob #331-TPSI-001 is going to require a 1" diameter hole in order for it to fit in your blank panel spot. The face of the panel is approximately 1-1/16" wide…

view full answer...

Answer 8

To install a brake controller in your 2007 Ford F-150 with a 4-way you need the #3035-P, the #37185, and a brake controller. For a brake controller I would recommend the Prodigy P2 Brake Controller part #90885. This is our best selling brake…

view full answer...

Answer 9

As long as it's not in the way for your daily vehicle use you will be just fine to leave your Primus IQ brake controller part #TK90160 installed all the time as that is what nearly everyone does with their controllers. Now if the controller is…

view full answer...

Answer 10

It sounds like you are speaking of the wires for the brake magnets. If this is correct, you will need to connect one of the wires to the brake controller output wire on your trailer connector and the other wire will need to be grounded to a clean…

view full answer...

Answer 11

Testing the brake controller is fairly easy. Sever the blue brake output wire near the brake controller leaving enough room to reconnect it and then apply the manual slide. Using a circuit tester like part #PTW2993, you should get output to the…

view full answer...

Answer 12

Yes you need the diode arrow to point towards the brake controller. That will allow the voltage to travel into the controller but not backfeed back on to the Highlander in any way. If you need a diode we have the part #RM-690.

view full answer...

Primus IQ Brake Controller Wiring Functions

Products Featured in This Question

Product Page this Question was Asked From

Featured Help Information

Instructions

Miscellaneous Media

Continue Researching