OT - Trailer Wiring Problem

DerbyDad03 wrote:
> Of course the trailer lights stop working - I have to drag it 300
> miles the day after tomorrow!
>
> Specifically, what has stopped working is the driver's side blinker
> and brake light, which are on the same output of the flat-four plug
> on the van. After chasing the problem in the trailer's harness for
> longer than I shoud have, I finally figured out that the problem is in
> the van, not the trailer.
>
> First, let me make it clear that the blinkers and brake lights on the
> van itself work fine. The problem exists somewhere in the wiring for
> the flat-four plug.
>
> The unloaded outputs at the flat-four sockets for the both trailer
> lights and the passenger side blinker/brake read ~12 volts, loaded
> they read ~11 volts. (I loaded it with a bare bulb, but I get the same
> readings with the trailer attached)
>
> However, the unloaded output at the flat-four for the driver's side
> blinker/brake is ~7 volts, loaded it's zero. Once again, it was loaded
> with a bare bulb, so the trailer has nothing to do with the issue.
>
> So, I know the problem is in the van's harness or the perhaps
> something with the pigtail, but I'm not sure what I should be looking
> for. The 2 feet or so of the pigtail that is exposed looks fine. After
> that it runs behind the trim into the bowels of the van. At first
> light, I guess I'm going to have to start pulling panels off. I took a
> quick look under the van (2004 Odessey) but it's late and dark, so
> I'll start again in the morning.
>
> What could cause the voltage at one output of the flat-four to be down
> by half and what would cause it to drop to zero under the load of a
> single trailer bulb?
>
> Thanks for any suggestions.
At the same time you are measuring 7 volts on the driver's blinker/brake
"bare bulb" is the van's blinker/brake lamp noticeably dimmer than when
the "bare bulb" is not connected?

On Jul 12, 12:48 am, Boden <[email protected]> wrote:
> DerbyDad03 wrote:
> > Of course the trailer lights stop working - I have to drag it 300
> > miles the day after tomorrow!
>
> > Specifically, what has stopped working is the driver's side blinker
> > and brake light, which are on  the same output of the flat-four plug
> > on the van. After chasing the problem in the trailer's harness for
> > longer than I shoud have, I finally figured out that the problem is in
> > the van, not the trailer.
>
> > First, let me make it clear that the blinkers and brake lights on the
> > van itself work fine. The problem exists somewhere in the wiring for
> > the flat-four plug.
>
> > The unloaded outputs at the flat-four sockets for the both trailer
> > lights and the passenger side blinker/brake read ~12 volts, loaded
> > they read ~11 volts. (I loaded it with a bare bulb, but I get the same
> > readings with the trailer attached)
>
> > However, the unloaded output at the flat-four for the driver's side
> > blinker/brake is ~7 volts, loaded it's zero. Once again, it was loaded
> > with a bare bulb, so the trailer has nothing to do with the issue.
>
> > So, I know the problem is in the van's harness or the perhaps
> > something with the pigtail, but I'm not sure what I should be looking
> > for. The 2 feet or so of the pigtail that is exposed looks fine. After
> > that it runs behind the trim into the bowels of the van. At first
> > light, I guess I'm going to have to start pulling panels off. I took a
> > quick look under the van (2004 Odessey) but it's late and dark, so
> > I'll start again in the morning.
>
> > What could cause the voltage at one output of the flat-four to be down
> > by half and what would cause it to drop to zero under the load of a
> > single trailer bulb?
>
> > Thanks for any suggestions.
>
> At the same time you are measuring 7 volts on the driver's blinker/brake
> "bare bulb" is the van's blinker/brake lamp noticeably dimmer than when
> the "bare bulb" is not connected?- Hide quoted text -
>
> - Show quoted text -

There is no noticeable difference in the van's lights. On this model
van, the brake and blinkers are not the same bulb like they are on the
trailer. The van has separate amber blinkers, so the wiring to them is
different than to the flat-four for the trailer - at some point,
anyway.

On Fri, 11 Jul 2008 22:02:23 -0700 (PDT), DerbyDad03
<[email protected]> wrote:

>On Jul 12, 12:48 am, Boden <[email protected]> wrote:
>> DerbyDad03 wrote:
>>
>> At the same time you are measuring 7 volts on the driver's blinker/brake
>> "bare bulb" is the van's blinker/brake lamp noticeably dimmer than when
>> the "bare bulb" is not connected?- Hide quoted text -
>>
>> - Show quoted text -
>
>There is no noticeable difference in the van's lights. On this model
>van, the brake and blinkers are not the same bulb like they are on the
>trailer. The van has separate amber blinkers, so the wiring to them is
>different than to the flat-four for the trailer - at some point,
>anyway.

I should have asked about this.

This probalby changes some of my advice in the other post. ... Ugh.
Worse than that. I made a mistake in my other post, not addressing
the need to run two wires from the tail light connector, I'm sorry.
See below.

While they sell some sort of adapter for people who put in their own
trailer wiring, I'll bet it costs 10 or 15 dollars.

I hadn't noticed that my car is like yours with amber blinkers, and
one can't just connect the blinker wire AND the brake wire to the same
wire to the trailer. I think if you do that, later, when you put on
the blinkers it will light the bulb on the other side two, because the
brake bulbs are connected together, but I'm not sure. I only know you
can't do it.

So I if you decide to run replacement wires from your current left
rear lights, you have to do this also.

RAther than run around looking for that device, since I wasn't at my
house, I went to Radio Shack and bought a bag of 2 diodes for a
dollar and a half. I think they had 2 or 5 amp diodes, either of
which is a lot more than the trailer lights use. I got the bigger
ones. Because I can never keep track for sure of the meaning of plus
and minus when it comes to diodes, I used an ohmmeter to verify which
direction current would go through the wire, and then I put in one
wire with those jumper wires to verify that I was right. Then I
soldered the same end of both diodes to the pigtail, and the ohter end
of the diodes to short pieces of wire, which I then stuck in the
connector as described in my othe post. The same connector served
both bulbs in my case, although it's conceivable that one bulb is in
the fender and one bulb somewhere else, like the van door. I think I
wrapped one layer of tape around the whole thing and then put back the
fuzzy cardboard that goes over all this stuff inside the trunk just
above the bumper.

DerbyDad03 wrote:
> On Jul 12, 12:48 am, Boden <[email protected]> wrote:
>
>>DerbyDad03 wrote:
>>
>>>Of course the trailer lights stop working - I have to drag it 300
>>>miles the day after tomorrow!
>>
>>>Specifically, what has stopped working is the driver's side blinker
>>>and brake light, which are on the same output of the flat-four plug
>>>on the van. After chasing the problem in the trailer's harness for
>>>longer than I shoud have, I finally figured out that the problem is in
>>>the van, not the trailer.
>>
>>>First, let me make it clear that the blinkers and brake lights on the
>>>van itself work fine. The problem exists somewhere in the wiring for
>>>the flat-four plug.
>>
>>>The unloaded outputs at the flat-four sockets for the both trailer
>>>lights and the passenger side blinker/brake read ~12 volts, loaded
>>>they read ~11 volts. (I loaded it with a bare bulb, but I get the same
>>>readings with the trailer attached)
>>
>>>However, the unloaded output at the flat-four for the driver's side
>>>blinker/brake is ~7 volts, loaded it's zero. Once again, it was loaded
>>>with a bare bulb, so the trailer has nothing to do with the issue.
>>
>>>So, I know the problem is in the van's harness or the perhaps
>>>something with the pigtail, but I'm not sure what I should be looking
>>>for. The 2 feet or so of the pigtail that is exposed looks fine. After
>>>that it runs behind the trim into the bowels of the van. At first
>>>light, I guess I'm going to have to start pulling panels off. I took a
>>>quick look under the van (2004 Odessey) but it's late and dark, so
>>>I'll start again in the morning.
>>
>>>What could cause the voltage at one output of the flat-four to be down
>>>by half and what would cause it to drop to zero under the load of a
>>>single trailer bulb?
>>
>>>Thanks for any suggestions.
>>
>>At the same time you are measuring 7 volts on the driver's blinker/brake
>>"bare bulb" is the van's blinker/brake lamp noticeably dimmer than when
>>the "bare bulb" is not connected?- Hide quoted text -
>>
>>- Show quoted text -
>
>
> There is no noticeable difference in the van's lights. On this model
> van, the brake and blinkers are not the same bulb like they are on the
> trailer. The van has separate amber blinkers, so the wiring to them is
> different than to the flat-four for the trailer - at some point,
> anyway.

In that case check the adapter box that converts the separate brake
lights and turn signals to the standard American scheme. Some of them
are crap and when they go bad all sorts of electrical weirdness can
happen. Had a friend with a Jeep Cherokee with all sorts of weird
issues; removing the trailer light adapter that a PO had installed
solved all of them. I found it one night with the parking lights
permanently on and the box smoking hot. (I guess it must have been
tapped into an always hot 12V feed somewhere, so it was likely a poor
installation from the beginning.)

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel