Troubleshooting Primus IQ Brake Controller that Shows N.C. on Display

Question

Question:

With my truck running and trailer hooked up. I am getting the . . Code on the controller, my trailer lights all work but the brakes wont. Also when manually depressing the controller it gives me the n.c. code, what do I need to do!!!

asked by: Dale S

0

Expert Reply:

There are 4 possible reasons why the Tekonsha Primus, # TK90160, is telling you N.C.

1. Trailer not connected to tow vehicle.
2. Trailer connected with open circuit on brake line.
3. Trailer connector disconnected or corroded.
4. Loss of trailer brake magnet ground.

The first one is easy enough to solve so we will go on to the second possible issue. An open circuit on the brake line or a short to the brake circuit could be caused by a couple of different issues. First, it is possible that there is corrosion or dirt in the trailer connector (see number 3 above) and that is causing a short from the 12 volt circuit to the brake circuit.

Corrosion can also build up behind the connectors where the wires attach where you cannot see it so be sure to check that as well. Check both the vehicle side and trailer side connectors.

If the brake controller checks out then you could have a problem with the trailer brake magnets. To test the brake magnets you can start with a visual inspection. If you can see the windings coming through then the magnets will need to be replaced. To further test the magnets I have included a link to an FAQ article that will help.

expert reply by: Jameson C

0

Bill I.

3/24/2020

After installing and using on one of my multiple trailers, everything worked fine with the brake controller, hooked up to one of my other trailers originally showed ‘c’ and showed voltage amount, then went to ‘nc’.Checked all connections redid all wire connections under the trailer with no avail, removed trailer plug , finally pulled the break away to test and see if there was a wiring issue or magnet problem of which trailer wheels locked up and could not even move the trailer in either direction still showing ‘nc’Only seems to be this trailer, where do I start testing

Reply

Chris R.

3/24/2020

This is an interesting problem....as it seems like you've ruled out most of the possible causes already. You said you removed the trailer plug - did you actually replace it, or did you wire it back in? If it's the same one, inspect the pins for any corrosion or debris that might be built up inside - cleaning out as needed. Also inspect the brake output wire between the connector and where you have the breakaway switch tied in. Let me know what you find and we'll go from there.

Reply

Christopher W.

7/25/2021

@ChrisR I installed this brake box today on a 2021 GMC Savana. I found the cables under the carpet and lined everything up according to the manuals (not colors). The only snag is that the vehicle manual said the vehicle needs 12 volt power to the engine fuse box (that is beyond me). However, I thought it would give the box set up a go. After installation the two small red lights come on and it reads NC when the side button is pushed and the number when the top button is pushed. I am concerned that it is not showing NC upon start up like the manual says it should (and did in my previous vehicle). Does a lit box mean we are good to go? I haven’t tested it with a trailer as I need it working BEFORE I pick up my camper. Thanks!

Reply

Victoria B.

7/29/2021

I spoke with my tech contact at Tekonsha today about what you're experiencing with your Primus IQ. We both think that what is happening is that your controller is not asleep when you are getting in and starting your van. The controller is supposed to display n.c. when it initially wakes up and then it will switch to showing only the . . When I shared your comment with my tech contact, he said the controller sounds like it is performing correctly.

Reply

See All (4) Replies to Bill I. ∨

Chad B.

6/17/2020

I installed this brake controller on my truck and when I hooked my camper up it said the slide control did nothing. It then said PL . I disconnected the plug, and plugged it back in. I set to the settings that the manual said to set it at, and still nothing. After driving it went back to PL. While driving, the numbers on the brake control were bouncing all over the place. It even does it without my camper hooked up to it.

Reply

Chris R.

6/22/2020

The "PL" error code indicates that the controller is somehow losing power. The Primus IQ receives power from the black 12V wire, so you'll need to make sure it's securely connected to the battery. If you installed the controller using a plug-in harness make sure there's not a blown fuse under the hood tied to this circuit.

Reply

Jamie M.

8/10/2020

I installed this on my truck using the adapter harness. Everything checks out on the controller. It shows n.c. when it's not connected then goes to . . When it's hooked up to my trailer, it shows .c. and when I press the brake pedal, it shows the increase proportional voltage. However, when tuning the unit with my trailer, I found that I am getting to braking from the trailer at all. This is a 5-year old trailer, so I'd be surprised if it was the brake magents. Is there a manual way to make the brake controller output a corresponding voltage so I can probe the truck 7-way connector?

Reply

Jon G.

8/21/2020

Yup! There is that larger button on the right side of the controller that will send back power to the brakes. If you have been testing your brakes without actually traveling then that would make sense as to why you aren't getting any braking. This is because the Primus IQ # TK90160 is a proportional controller so if it doesn't sense any movement then it won't send much power back to the trailer brakes since it technically isn't needed.

Reply

Answer 1

Yes, going from a 4 leaf to a 6 leaf spring would add slightly to your ride height. For example, if the current 4 leaf spring has 3/8" thick leaves, and you go to a 6 leaf spring with 3/8" thick leaves, you would be adding 3/4" of…

view full answer...

Answer 2

One of the biggest differences between the 6-leaf 5,000 lb trailer axle leaf spring part #UG34FR and the 4-leaf part #e44SR is the length. The 6-leaf setup is 30 inches long and the 4-leaf setup is 25-1/4 inches long. In general though the number of…

view full answer...

Answer 3

Yes, the Brass Tire Sensors for TireMinder TPMS #TM-2Brass would fit and work on the valve stems of your 2023 Jeep Wrangler.

view full answer...

Answer 4

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 5

You can use leaf springs that are rated higher than the axle without any issues as long as they measure the correct measurement for your trailer. For example the 6-leaf double eye spring for 7,000 lb axles part #e64SR measures 24-7/8" eye to…

view full answer...

Answer 6

The number of leaves on a leaf spring does not dictate strength or capacity, so as you said, a 3000lb rated leaf spring (6,000lb axle capacity) can have various numbers of leaves since it is up to how the manufacture designed it. I wouldn't look…

view full answer...

Answer 7

Since power is reaching one of your brake assemblies, the issue could be caused by a number of other factors such as poor ground connections, brakes need to be adjusted, the electric brake circuit, or bad brake magnets. The first step I would take is…

view full answer...

Answer 8

With you having 2- 3500lb axles your maximum capacity is 7000lbs evenly distributed over both axles. With the trailer weight of 8240lbs you definitely risk damaging the axles, suspension and other parts of the trailer. Trailer Axles will sometimes…

view full answer...

Answer 9

Your problem could result from even a slightly dirty, corroded or loose connector (or individual connector pin) anywhere from the dash all the way to the 7-way. Corrosion can sometimes appear as a green or white film (connectors do not have to look…

view full answer...

Answer 10

Other than saying that the air bags need to be kept between 5 and 100 psi, Firestone does not offer much in the way of specifics. The instructions mention that as a general rule of thumb, 1 psi will support approximately 40 lbs of load. Your best bet…

view full answer...

Answer 11

What you described is perfectly normal. When not connected to a trailer the Prodigy P2 part #90885 will show two dots like you described. After a period of inactivity the controller will go into sleep mode. It doesn't turn off with the vehicle…

view full answer...

Answer 12

The fuse for the trailer running lights on your 2005 GMC Sierra 1500 is going to be located in the engine bay fuse box and will be labeled as the trailer parking lights. If you just visually inspected the fuse it may have been missed because not all…

view full answer...

Troubleshooting Primus IQ Brake Controller that Shows N.C. on Display

Product Page this Question was Asked From

Featured Help Information

Instructions

Miscellaneous Media

Continue Researching