Trailer Light Converter Failure?

[SpartanFan]

Hey Everyone,

Twice now, I've tried to pick up our new (to us) '78 Tradewind. And twice I've come home empty due to failed trailer lights. My TV is a 2001 Toyota Tundra and I believe it has a failing trailer light converter.

The trailer lights are controlled by the converter module that sends the signals to a 4-pin flat. That 4-pin is plugged into a pigtail that connects to the 7-pin. The remaining lines from the 7 pin lead to the battery, brake controller, and ground per the instructions. The controller is a Tekonsha P3.

Prior to installing the 7-pin, I used the 4 pin without issue for 12 years.

When the trailer was plugged into it yesterday, no lights worked on the trailer, but I believe that the trailer brakes were operating. (I could hear them humming when my wife used the manual actuator on the brake controller.) Checking the 7-pin, I got no voltage on any of the pins other than the lower right which produced a small (1.6V) voltage with the brakes applied.)

Going back to the original 4-pin, I had no voltage there either. Two hours later I was home and trying to chase down a faulty connection somewhere. My neighbor and I disconnected everything to the converter box. We we reassembled everything and I had good voltage at all the proper pins. (Lights and brakes) Hurray! Bad connection - problem fixed! Drove back today to pick up the Tradewind (another two hours). Same Problem! No lights on at trailer. Checked the voltage again and found low readings (well under the 12-13v we were getting the previous night.) Tried them once more and when I tested the pins again, I was back to no voltage. Just like the day before!

It appears that the trailer has been converted to the "standard" 7 pin connection at some point. We confirmed that they still work with the owner's TV and that his pins are the same configuration as mine. Drove home (2 hours) for the second day in a row without an AS in tow.

Are converter box failures common? Also, the converter that I originally installed was a Toyota factory unit that I ordered from the dealership. Not even sure that they're available for a 15 year old truck anymore. As such, is there any particular model or specifications that I should be looking for to replace the faulty model? My thought/concern right now is that there was a lot more draw on this than any previous trailer that I've used. (Basically a collection of boat and utility trailers with the generic screw on trailer light assemblies.)

Thoughts and opinions are appreciated.

Thanks.

Jeff

[SpartanFan]

Edited to add:

I just confirmed that there are signals (11-12v) going into the converter for brakes, running lights, and turn signals, as well as the separate power going to it as well. Really looking like the converter box.

Advice appreciated.

[ROBERT CROSS]

Is this the style converter of which you speak....?


Never used one when doing our '63 Safari wiring.

A test light worked very well to trace the wires to make the proper connections...plus it's a handy tool to have in the AS tool kit, probably less expensive also.

Bob

[SpartanFan]

It's similar to that except it has and additional 12 source coming in. I believe that the current sent to the tail lights comes from that source so as not to tax the tail light circuitry in the truck.

[BoscoMN]

Always look for a shorted or loose wire first.

This is a shot in the dark, but you could move the 12 V positive input into the converter box to the same line that is providing the 12 V positive to the 7 pin connector. I'm wondering if there may be a voltage differential between the two 12 volt sources and that this is placing an unusual negative voltage flow into the converter. That way if there is some mis-wire on the trailer lights you won't get any reverse current going into the converter box.

Another thing to consider is that some 7 pin connector wiring kits at etrailer.com include a diode in-line for all connections to the trailer to eliminate such potential issues in case the trailer signal light circuit is wired to something else in the trailer. An example would be where a previous owner tied into the tail light circuit to get 12 volts for an add-on device like a rear mounted camera.

http://www.etrailer.com/Accessories-...er/RM-690.html

[ROBERT CROSS]

Originally Posted by SpartanFan

It's similar to that except it has and additional 12 source coming in. I believe that the current sent to the tail lights comes from that source so as not to tax the tail light circuitry in the truck.

The 12v in could/should be the 'charge' line for the coach batteries.

Bob

[SpartanFan]

Originally Posted by ROBERT CROSS

The 12v in could/should be the 'charge' line for the coach batteries.

Bob

I don't beliveve that's the case. Much like in the photo that you posted, the Toyota converter's output goes to a 4-pin flat connector (which worked fine for years). That 4-pin plugs into a pigtail on the back of the 7-blade connector that I purchased from etrailer a few months back. I would assume that the 'charge' line would be the one that I connected from the 7-blade to the battery.

I like the idea of powering the AS lights on circuits that are isolated from the TV lights and since the old converter's wiring is still present, it's easy to do. I was just curious if there were any models of converters that are preferred or avoided by the group. Yesterday I ordered the Hopkins "Heavy Duty" model. (46365)



Here's hoping that it does the trick.

[SpartanFan]

Originally Posted by BoscoMN

Always look for a shorted or loose wire first.

This is a shot in the dark, but you could move the 12 V positive input into the converter box to the same line that is providing the 12 V positive to the 7 pin connector. I'm wondering if there may be a voltage differential between the two 12 volt sources and that this is placing an unusual negative voltage flow into the converter. That way if there is some mis-wire on the trailer lights you won't get any reverse current going into the converter box.

Another thing to consider is that some 7 pin connector wiring kits at etrailer.com include a diode in-line for all connections to the trailer to eliminate such potential issues in case the trailer signal light circuit is wired to something else in the trailer. An example would be where a previous owner tied into the tail light circuit to get 12 volts for an add-on device like a rear mounted camera.

http://www.etrailer.com/Accessories-...er/RM-690.html

I'm curious about this. I would have thought that the two 12v lines would power completely different items (trailer lights and whatever the constant 12v line connects to...battery charger?) and so would no be able to interfere with each other.

Is there something I'm missing?

I'm loving the learning process so far.

...well, except for that part where I keep driving home without the Airstream.

[SpartanFan]

Originally Posted by ROBERT CROSS

The 12v in could/should be the 'charge' line for the coach batteries.

Bob

I don't believe so. The output on the converter goes to a 4-pin flat connector, which worked fine for years. That connecter now plugs into a pigtail that leads into the 7-pin that I installed a couple of months ago. I would think that the 'charge' line would be the wire that is connected directly from the truck battery to the 7-pin.

I like the idea of an independently powered set of trailer lights that are isolated from the truck lights. Honestly, looking at the fuses for the truck's taillights, I'm not sure that they could withstand the increased load from the trailer.

Yesterday I ordered the Hopkins 'Heavy Duty' powered converter (Model 46365).

Here's hoping that it does the trick!

[SpartanFan]

Patrick McManus once wrote that "Shortly after man invented the wheel, he invented the trailer. Ever since then, he's been trying to get the lights to work."

The new converter box has been installed and I now have correct signals and voltages to all the pins...but one. When I press the brake pedal, I receive 12 volts on the right side stop/turn light pin, but I measure a little under 4 volts on the left side pin.

As I described before, the 4-pin flat that plugs into the back of the 7-pin to power the lights measures 12 volts on both pins. And the 4 pin throughput, alongside the 7-pin, also measures 12 volts out to both. Also, when measuring the 4 pin, I receive the same measurements regardless if I measure against the 4 pin or 7 pin ground, so I don't believe that grounding is an issue in this case. (I did disconnect it, clean it, sand it bare, and reconnect it, just to be certain.)

Is it possible that I had a fried converter box and I received a bum 7-pin connector?

Pretty frustrated.

Jeff

[AlbertF]

I've had three converters fail in the past 10 years. That's always a possibility, and I now travel with a spare.