Date: Sat, 10 Oct 2009 22:32:11 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <firstname.lastname@example.org>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Brake light circuit current with trailer,
WAS: Re: No High Beams
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
maybe in the last line you mean the brake lights, and not the tail lights,
come on when the brake pedal is pressed.
so it's working then ?
----- Original Message -----
From: "Rocket J Squirrel" <camping.elliott@GMAIL.COM>
Sent: Saturday, October 10, 2009 10:05 PM
Subject: Re: Brake light circuit current with trailer, WAS: Re: No High
> You're right -- it's unclear whether the problem is fixed, or what the
> problem was that caused the fuses to pop.
> There are two flavors of 3 to 2 tail light converters: powered and
> unpowered. Unpowered do the conversion and power the lamps from the same
> circuits that drive the van's tail lights. Powered converters do the
> conversion but have a +12 wire to draw trailer lamp lighting current from
> the battery so the vehicle's lamp circuits don't see the load of the extra
> I can tell the converter is working fine because the current through the
> fuse is 4A when there is no trailer connected, and 4A when the trailer is
> connected. The tail lights on the trailer do come on when the brake pedal
> is depressed.*
> * Or even mildly sad.
> Mike "Rocket J Squirrel" Elliott
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
> Bend, OR
> On 10/10/2009 6:17 PM Scott Daniel - Turbovans wrote:
>> so your problem is still not fixed ?
>> to me, that's not really quite clear.
>> and .........re :
>> "The converter is designed to make
>> sure that no additional loading is presented to the circuit. "
>> really ?
>> I never use them, but my understanding is that they are for converting
>> from a '3 filament system ' ( vanagon - a separate filament for tail,
>> turn, and brake )
>> to a '2 filament system' ( where there is tail, and brake, but brake on
>> one side turns into turn signal when the turn signal is engaged - a very
>> dumb system I think, and still, oddly, used in brand new American cars
>> .........without even amber turn signal lenses even ) ...
>> but ....
>> just divies up from 3 to 2, or .........where you are going the other
>> way ..........from 2 to 3 if there is such a converter.
>> I would start over.
>> it could be that you have a bad converting gizmo.
>> here is what I Actually recommend, which I have done to my utility
>> trailer and it works dead frickin' perfect.
>> Get motorcycle amber turn signals.
>> They are often mounted on a rubber stalk too, so bumping them doesn't
>> brake them off.
>> I have mine under the rear of my utility trailer .
>> this way, I have a nice 3 filament system with amber turn signals on my
>> and same on my trailer.
>> And the turn signal and 4 way flasher can handle the load of 3 or even 6
>> turn signal bulbs all flashing at once.
>> I think you have a bad converter unit perhaps, or are trying to use it
>> incorrectly or something along those lines.
>> I don't trust sealed electronic gizmo's like that very much anyway. If
>> they work fine ......
>> but if any doubt, get rid of that thing and wire it to truly match your
>> Vanagon's system.
>> then there won't be any balonie about blowing fuses etc.
>> Find a motorcylce junk yard - used mc turn signal assemblies are cheap I
>> would imagine.
>> ----- Original Message ----- From: "Rocket J Squirrel"
>> To: <vanagon@GERRY.VANAGON.COM>
>> Sent: Saturday, October 10, 2009 5:45 PM
>> Subject: Brake light circuit current with trailer, WAS: Re: No High Beams
>>> A continuation of a side thread.
>>> On 9/29/09 I opened my big fat yap to comment on a thread in which a
>>> member said that he was blowing high beam fuses after going to higher
>>> wattage lamps (see "No High Beams").
>>> I helpfully added that on my van, fuse #8 (fusebox, 1984) popped moments
>>> after applying the brakes when my little trailer was hooked up. Changing
>>> the 8A fuse to a 16A fuse* fixed the problem.
>>> I thought that contributing this anecdote to the thread would help
>>> illustrate how adding more or bigger bulbs to a lighting circuit might
>>> exceed the current rating of the fuse.
>>> Ohm's Law says one 21W bulb will draw 1.75A at 12V, and around 1.95A at
>>> 13.4V (alternator booted). With four 21W bulbs that's nearly 8A, which
>>> would pretty quickly pop the fuse, although it should have taken a few
>>> seconds, and not the brief moment that I witnessed. My guess was that
>>> bulbs' inrush current** was responsible for the fast blow.
>>> In the thread, a couple list members took me to task for not taking
>>> current measurements, I was speaking through my backside. So I measured
>>> the currents:***
>>> With stock-type brake lights, no trailer: 3.9 amps @ 13.4V (1.95A/bulb
>>> which is in agreement with the calculated 2A/bulb @ 13.5V.)
>>> With trailer: Exactly the same. I had forgotten that I had wired in a
>>> "powered" 3-to-2 tail light converter****
>>> So. Why the heck did the 8A fuse pop the first time I pressed on the
>>> pedal once the trailer was connected. The converter is designed to make
>>> sure that no additional loading is presented to the circuit. And my
>>> measurements confirm it. I think it's fair to say that if there was a
>>> momentary short or glitch in the trailer pigtail or wiring, the
>>> would have had to deal with it, not the dash fuse.
>>> I should point out that this scenario played out exactly the same way
>>> in August 2008 when I first hooked up the trailer for my Escape From
>>> Science is baffled.
>>> * These GBC "ceramic torpedo" fuses only come in three flavors: 8A,
>>> 16A, 25A
>>> ** Inrush current, I felt, was the reason why the fuse was popping so
>>> quickly since light bulbs will draw 5 to 10 times as much current when
>>> power is first applied than when they are hot.
>>> *** My reader will recall that I can't be trusted with an ammeter:
>>> none of
>>> my ammeters have intact fuses in them. I've blown them all. To make
>>> measurements I made a 0.01 ohm (+/-) "resistor" using 19'' of 40-mil
>>> diameter solid-core copper wire soldered across a blown fuse. By
>>> the voltage drop across this current-sampling resistance and applying I
>>> E/R I had my ammeter. Easy as cake.
>>> **** The trailer has two bulbs, one on right, one on left, Vanagon uses
>>> four bulbs: right turn, left turn, and two brake lights wired together,
>>> three circuits total. A converter is needed to drive the two-circuit
>>> trailer from the three circuit van. A powered converter connects to the
>>> battery to avoid additional loading on the original lighting circuits.
>>> Mike "Rocket J Squirrel" Elliott
>>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>>> 74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
>>> Bend, OR