Odd readout on Tekonsha brake controller

[pauloh]

I'm barely able to get on the internet here in Yellowstone (via a Verizon hotspot) so I apologize for not researching the forums very long for a possible answer about this. The other day when I was ready to leave my Tetons campsite, heading for Yellowstone a couple hours away, I noticed my Tekonsha brake controller was reading 1.0 volts (flickering to .9 or .8) as if I was pressing the brake slightly even though I was not. Normally it sits at "0" volts when no brakes are applied. It still increased semi-normally when I did push the brake pedal, returning to about 1.0 again when I let up. I tried unplugging the controller, re-inserting the main cable at the hitch, and turning the engine on/off. (My Tekonsha is wired to my TV with factory-supplied harnesses, I remove it when back home.) Finally I drove off with it this way. I am not sure if light brakes were being applied to the Trailmanor but it seemed like perhaps they were. I forgot about touching the drum to see if they were hot. But along the way (on long flat stretches with no traffic) I tried adjusting the Tekonsha, moved the maximum voltage down from around 5.0 volts (the factory setting I think) to 1.0 then back again, and checked that the manual lever still activated the trailer brakes (it definitely did), and the regular brakes worked when needed throughout, but in a nutshell it seemed the problem went away on its own and eventually the Tekonsha finally read "0 volts" when I wasn't applying the brake. I've been parked for several days but will be on the road again by Friday…does this seem more likely a problem caused by the controller, my tow vehicle, or maybe the trailer brakes somehow? I inspected the brake wiring at each hub, seems intact and the way I had it when I re-did things a couple years ago. Thanks for any thoughts on this.

Sounds like a Puzzler worthy of Click and Clack on NPR. Beats me, but I'm betting somebody on here will have a meaningful insight.
Enjoy Yellowstone.

[tentcamper]

do you only get the voltage on the controller when the trailer is connected, or even if trailer is disconnected?

[Bill]

The P3 is a very nice controller. In response to your query, I pulled up the owner's manual. It has a lot of interesting settings, including Hill Hold, that look similar but don't really seem to explain what you saw.

I did see one caution. Don't install it near any RF-generating equipment such as a cell phone or two-way radio. You don't have a cell phone near it, do you? Even if it is not being used, it could cause a problem. I don't know if a Bluetooth connection would count.

I also spotted one thing about the P3 that I really love. Instead of reading out the voltage being applied to the brakes (you reported about 1 volt with no brake pedal push), it can be set to read out the current to the brakes. Since trailer brakes are electromagnets, and magnets operate according to the current through them, I would set the controller to read out current, not voltage. The voltage applied to the brake circuit is meaningless in some situations, and in general is not really what you want to know. So why do brake controllers read out voltage? A voltage readout is cheap, and a current readout costs more. So almost all of the manufacturers have gone cheap. One of my pet peeves for years.

In response to your question, if this happens again I would use the controller to read out the current through the brakes. If it reads zero, you know that the brakes are not being activated, regardless of what the voltage readout says.

Just my thought.

Bill

[pauloh]

Thanks so much for the helpful info and suggestions. I am now moved to another campground (with decent Verizon coverage now!) since the initial message...the same thing happened while in transit, a 1.0V readout for a short time after hooking up then it went to zero by the time I got out of the campground (last time it stayed that way til I had traveled a couple of highway miles.) To answer tentcamper's question, it only does this when connected to the TM, the P3 "knows" when the TM is not connected and shows "no trailer connected" at that time, so no readouts then (as far as I know, I'll look at that more carefully). Bill, thanks for so politely saying "READ THE MANUAL" which is of course a good idea! I did read it when setting it up a couple years ago, the P3 has worked perfectly ever since til now, but I'll certainly take a look again, try looking at current vs. voltage, and when I hook up again in a few days, will see if I can work it out. I do in fact have my cell phone in a cradle on the dash (it's often my GPS) so could try turning it off, but I've had it there for thousands of miles with no issues til now.

I bought this Tekonsha P3 based on favorable comments here a few years ago and yes it's a very nice unit. Somehow I doubt it's the controller, but rather some problem the controller is "reporting". I was envisioning (panicking!) the brakes locking up completely when I first had the problem but I don't think that'll happen and if I don't get it resolved here will have my trailer guy back home go over the brake system, I'm due for a checkup anyway. If I get to the bottom of it I will report here again.

[Bill]

Originally Posted by pauloh

Bill, thanks for so politely saying "READ THE MANUAL" which is of course a good idea! I did read it when setting it up a couple years ago, the P3 has worked perfectly ever since til now, but I'll certainly take a look again, try looking at current vs. voltage.

Paul -

That was no at all my intent. I also have a Prodigy, though not a P3, and before I wade into a discussion and try to help, I like to review everything I can find, to see if there is something I've forgotten or didn't know. Keeps me from making a fool of myself too often.

Anyway, I really would like to know what the amp-meter says at the time when it happens. If you find out, let us know.

Bill

[tentcamper]

I asked the question about the reading when the trailer was not connected. I was wondering it there was a slight short on the seven pin connection. I had an issue many years ago where one strand from the pin next to the brake pin was shorted to the brake pin and it gave me some strange readings. But it also at times acted like a trailer was connected when one was not.

[pauloh]

Bill, I've benefited from your advice here so often (past posts and my own questions), thanks again. I will certainly look for that amp reading when I connect again in a couple days and report (if I can get on the internet, or when back home if not). I'm almost hoping the problem re-occurs so I can take a look at that!
Tentcamper, your suggestion is also worth a good look, I will inspect both ends of the connectors before hookup.
Thank you both.

[pauloh]

The last paragraph below may explain the problem I've been having. The rest of this post I hope answers what Bill asked about.

Since my initial post, I have returned home, stopping two places along the way to camp. The first time I moved, I had no appearances of the "odd readout" on the Tekonsha. The last time (on my way home yesterday) the Tekonsha showed the odd readout of .10 or .20 volts when I first got under way (should be zero). In reply to Bill's suggestion, I scrolled to the "troubleshooting" menu options on the unit and saw the following information, note that brakes were NOT being applied at this time:
Battery voltage: 14.02 (to 14.04) volts
Stoplight: .04 volts (user manual seems to indicate this should be zero. My headlights/tail lights were on at this time if that could be significant.)
Output voltage .10
Input current: 0.0 amps

If I understand Bill correctly, this would indicate that no current was being supplied to the brakes at the time of the odd reading (maybe the voltage was just too low? The first time I noticed this problem it was going as high as 1.0 volts, not .10 volts) Within 10 minutes of driving, I happened to see the .10-.20 voltage reading drop to .10 and then back to the normal "0 volts" (except when braking of course), this happened in a couple of seconds as I glanced down at the display (I was not touching the unit, reference my comment in the next paragraph.)

I have noticed one more thing from reading the manual carefully. When the trailer is not connected, the Tekonsha's screen normally displays the company's logo. If the manual braking knob on the bottom of the unit is turned, the unit will start displaying "NO Trailer Connection" alternating with a picture of a trailer with a slash through it. I know I have on occasion seen this warning screen at times when the trailer was not connected, but I didn't realize its significance (I KNEW the trailer wasn't connected as I wasn't towing it, thought that was what it was telling me). I almost never use the manual control lever, and it would be nearly impossible to hit it accidentally the way I have the unit mounted, but I wonder if it is self-activating just enough to engage a tiny bit, causing the warning message when not connected, and the small voltage reading when the TM is connected. It's spring-loaded to return to the normal (off) position, and seems like goes fully back off when I actuate/release it. I'm going to leave the Tekonsha in my vehicle for a while (I usually remove it between TM travels) and keep an eye on this screen. Pressing the lever just a bit does in fact make the readout go to .10-.20 but I have to push it a fair distance before it starts to change the display. The unit is in good condition, I store it in the factory case when not in use, but maybe the switch is the culprit and needs cleaning or a factory check.

[commodor47]

There is one more place that could be causing the issue. Check the wire connections from your TV to the 7-pin Bargman Connector. I had a similar issue (not exactly the same) that turned out to be corroded wire connectors. Replacing the Bargman Connector and making sure the wire connections from the TV to the Bargman were sealed corrected my issue.

Dick