prodigy brake controller q's....

[Herb P]

So I took my 1700 for a test drive this weekend with the newly wired prodigy. Everything appeared to work great but in retrospect, something about it bothered me....

On decelleration, the numbers on the prodigy do seem to cycle up and it seems to me that in so doing, it is applying the brakes. This doesn't seem overly intuitive to me. The numbers also increase when I brake and I can definitely feel that the trailer is helping slow us down... On a slight incline, in neutral, I can use the manual lever and it will stop the TV/trailer as well... So it appears to work "fine"...

It's the numbers present during acceleration that worries me.

I called Tekonsha and spoke with someone in tech support who said they'd never seen this and that the unit should not do that. On acceleration the unit should display ".c" or ".c.". She confirmed my wiring and it is correct (based on my description to her, including which Toyota specific wire I tapped in to). So now she wants me to dismantle one of my trailer brakes, and hook up the electro magnet from it to the blue wire (to provide an inductive load, basically) and drive around with that to see if the problem goes away... It's not clear what that's going to accomplish but whatever...

So, since tekonsha's tech support is largely unhelpful, I'm hoping someone here will be able to fill in some knowledge.... This is all new to me.

[Byron Kinnaman]

The first think I would check is to make sure when just sitting it indicates ".c." The only time there should be a number is when the brake light switch is activated. The ".c." indicates that the brakes are connected.

The number going up when accelerating means that the controller thinks you're in reverse and applying the brakes.

Maybe the brake light switch wire is connected to the wrong side of the brake light switch.

[Brian B-P]

...On decelleration, the numbers on the prodigy do seem to cycle up and it seems to me that in so doing, it is applying the brakes. This doesn't seem overly intuitive to me...

The displayed number should match the deceleration you feel (not really the pedal effort) quite directly, as long as the "boost" setting is not used. Make sure boost if off (no second dot in the display) to get a feel for the basic behaviour.

...It's the numbers present during acceleration that worries me....

If I read this correctly, the controller is applying brake current both when accelerating and when decelerating (presumably using the tug's brakes, not just coasting or engine braking). If so, then the brake pedal input signal connection can't be reversed - it must be on all of the time! I agree with Bryon - acceleration with a brake signal looks like braking in reverse to the controller.

When just sitting without brakes, the controller just shows that "connected" indication. When sitting still (without acceleration in any direction) but with the brake pedal applied, the Prodigy ramps the output voltage up to (I think) 20% of the full setting, and holds it until the brake pedal (brake light signal) is released. So, Herb, when sitting still, does the controller respond to the brake pedal? If so, you know the brake application signal is being received; if not, there's something wrong in the red wire connection.

[Herb P]

If I read this correctly, the controller is applying brake current both when accelerating and when decelerating (presumably using the tug's brakes, not just coasting or engine braking). If so, then the brake pedal input signal connection can't be reversed - it must be on all of the time! I agree with Bryon - acceleration with a brake signal looks like braking in reverse to the controller.

When just sitting without brakes, the controller just shows that "connected" indication. When sitting still (without acceleration in any direction) but with the brake pedal applied, the Prodigy ramps the output voltage up to (I think) 20% of the full setting, and holds it until the brake pedal (brake light signal) is released. So, Herb, when sitting still, does the controller respond to the brake pedal? If so, you know the brake application signal is being received; if not, there's something wrong in the red wire connection.

I'm positive I used the correct brake wire and the behavior is consistant with that. So based on what you guys are saying, it sounds like I've done everything right. This morning (last night was consumed with trailer curtains and plumbing), I hooked the truck up to the trailer harness and couldn't get the trailer lights to come on. No amount of wiggling of the 7 pin connector could get them to come on... I finally timed out and went to work. On the long commute I wondered if that was a sign that maybe there's a bad ground at the trailer or connector such that the hitch itself was completing the ground circuit which would lead to all sorts of squirrely behavior ...

Clearly more diagnosis is required.

[Sean Janusheske]

Herb,
Do a simple check.
Without disconnecting anything, use your multimeter to check the voltage in the red wire.
If you have voltage without applying the brakes, then you may have connected to the "hot" side of the brake switch by mistake.
Right brake wire, but wrong side of switch.

As stated previously, the prodigy would be sensing your acceleration as a "deceleration in reverse" and thus send a proportional signal to actuate the trailer brakes.
In other words the inertial sensor (pendulum) is feeling and reacting to both the acceleration and deceleration because it has a continuous power source, not the intermittent power as when the brake is applied and the brake lights come on.

Hope I didn't confuse you or anyone else.

[Byron Kinnaman]

Herb,
Do a simple check.
Without disconnecting anything, use your multimeter to check the voltage in the red wire.
If you have voltage without applying the brakes, then you may have connected to the "hot" side of the brake switch by mistake.
Right brake wire, but wrong side of switch.

As stated previously, the prodigy would be sensing your acceleration as a "deceleration in reverse" and thus send a proportional signal to actuate the trailer brakes.
In other words the inertial sensor (pendulum) is feeling and reacting to both the acceleration and deceleration because it has a continuous power source, not the intermittent power as when the brake is applied and the brake lights come on.

Hope I didn't confuse you or anyone else.

My thoughts, exactly.

[Brian B-P]

The connector realization is key - there's no point in troubleshooting the controller until it is known to be connected to something!

The trailer wiring can be checked with the tug connected by just probing between pins with a voltmeter to find the +12V wire (to confirm the battery and ground connections are on the right pins), then disconnecting the battery and probing with an ohmmeter (okay, same meter, turn the knob...) to see if the brakes are connected. A pair of brake magnets in parallel should offer a little less than two ohms of resistance between the (blue) brake control wire and (white) "ground". To get my brakes working, I saw four ohms, and knew a wire to one magnet was failed; no resistance would be a short, infinite resistance would be no brake magnets connected, and the controller wouldn't like either of those things.

If the problem were just that there was no valid brake magnet connection - the item the technical assistance person was trying to check off the list - the controller should just say "nc", so I doubt it's that simple.

..So, Herb, when sitting still, does the controller respond to the brake pedal? If so, you know the brake application signal is being received; if not, there's something wrong in the red wire connection.

I'm positive I used the correct brake wire and the behavior is consistant with that...

I'm taking this to mean that the controller changes what it is doing when the pedal is pushed and released, and therefore the red wire doesn't have an always-on signal... right? I think it's still worth checking with a meter, as Sean suggested.

[Sean Janusheske]

Concur with your troubleshooting guidance.

[Herb P]

Concur with your troubleshooting guidance.

ok, y'all were right. I was misinterpreting the output of the display and while I had it hooked to the 'green wire with the white tracer' per toyota and per my schematic, I shouldn't have been quite so positive. There was another 'green wire with white tracer' that turned out to be the one I wanted. Moved to that and all is well...

So what I was seeing was what you all were describing, and I was incorrectly misinterpreting the display.

I also cleaned up the trailer connector and it seems to make a nice positive connection now, instead of an intermittent one.

Thanks everyone for your help.

[Byron Kinnaman]

ok, y'all were right. I was misinterpreting the output of the display and while I had it hooked to the 'green wire with the white tracer' per toyota and per my schematic, I shouldn't have been quite so positive. There was another 'green wire with white tracer' that turned out to be the one I wanted. Moved to that and all is well...

So what I was seeing was what you all were describing, and I was incorrectly misinterpreting the display.

I also cleaned up the trailer connector and it seems to make a nice positive connection now, instead of an intermittent one.

Thanks everyone for your help.

Thanks for letting us know what the problem was.