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Topic: Towed Car Lighting Problem (Read 805 times) previous topic - next topic

Towed Car Lighting Problem

We have a 2001 U270 and tow a 2004 Chevrolet Avalanche pickup. In 2006 we had M&G in Athens, Texas install diodes in the pickup's tail light assemblies and this has been working just fine up to now.

Now all of the tail light functions (running lights, left turn signals, right turn signals and brake lights) work perfectly on the pickup when it is disconnected from the coach. When connected though everything works except for the right brake light.
 
As I remembered that they put two diodes in each tail light assembly I assumed that one had gone bad so I drove the pickup to a shop in Houston which specializes in this kind of work. They drove the pickup (without me) into a building where they could test for this problem. They said there was no problem with the diodes and that I needed this "gismo" replaced on the coach which is stored at our country place 95 miles away. Hopefully here is a picture of the gismo.

I'm a bit reluctant to tear into the coach wiring as my logic tells me that the problem must be with the pickup. The coach has the original 6 way socket which is used for the pickup and it has an additional 7 way socket siamesed in by FOT some years ago for my cargo trailer. All of the light functions are working fine (including the right brake light) on the cargo trailer. I really dread tearing into this big bundle of wiring which is all taped together and tied to the rear cross-member of the coach.

Any help or suggestions to better diagnose the problem before doing this will be appreciated.

Robert




Rob & Di
2001 U270 34'

Re: Towed Car Lighting Problem

Reply #1 –
I too tow my 04 Avalanche, but just had a set of extra bulbs installed into the rear taillight housings and ran wires thru the frame rails.  I did not want to deal with diodes or messing with the Chevy wiring systems.
Dave Cobb
Buckhorn Lake Resort The Club, #6202, Kerrville TX
check the map.  I do rent it out when I am traveling!
2001, U320, 36' #5887, in Kerrville, FT Club #17006, (7/23 to present)
2024 Jeep Grand Cherokee L, Summit, white
EX: 98 U295, 36' #5219, (mid door), (4/13-10/23)
EX: 93 U225, 36' (4/11 to 4/13)

Re: Towed Car Lighting Problem

Reply #2 –
Thanks but I'd sure like to get this fixed as it stands. The Avalanche has been driven about 80k plus miles and towed another 80k plus miles without this problem. Also I'm trying to ascertain if the problem is with the coach (as the Houston shop believes) or with the Avalanche before making repairs.

Before we towed the Avalanche we towed a 2001 Jeep Wrangler. This had additional bulbs mounted in the tail light assemblies. Although the bulbs burned brightly they appeared dim as they couldn't be mounted in focus areas of the lenses. For this reason I elected to go the diode direction this time.

If all else fails I might go back to this way.
Rob & Di
2001 U270 34'

Re: Towed Car Lighting Problem

Reply #3 –
The only 'gizmo' is an electronic lamp converter. Your Foretravel has separate turn signals from the tail/brake light. The converter combines them. They RARELY go out. You are more likely to have a wiring problem at the coach.

Last trip I had my setup stop working. I have a separate light bar on my Tahoe, and convert my coach plug to a 4 wire on the Tahoe. I went nuts troubleshooting. End result was that I was inserting the 6 wire connect into the coach upside down, which takes rare talent. Made Gary Omel's day...

There are 'plug in' troubleshooting devices for the connector, and inexpensive test circuit lights with sharp probes that will pierce the insulation and check both sides of the converter. Get one with an LED and it should last forever.
circuit tester LED | eBay
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Towed Car Lighting Problem

Reply #4 –
Rob and Di,

I just had a similar problem: when I put the left turn signal on in the coach and hit the brakes at the same time, the turn signals dimmed and stopped blinking. I thought it was in the toad. It wasn't; it was the same "trailer converter" box that your picture illustrates. It was only $13 from NAPA and is easy to replace. Normally it is tucked inside the driver's side rear bumper and receives its power from a small harness of wires coming from the driver's side rear tail light. Mine was attached by tie wraps. All one needs are wire strippers, butt connectors and a bunch of rags to clean off the dirt from the old converter. Just match up the colors. Instructions are provided with the converter.
Don Hay
'92 Grandvilla, U-280
The Hayfever Express
Build #4055
'97 GEO Tracker
Life is like licking honey off a thorn.

Re: Towed Car Lighting Problem

Reply #5 –
I had to replace one on my last coach. They do not last forever.  It is an easy fix and should be right by the engine compartment door.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Towed Car Lighting Problem

Reply #6 –
Thanks again. Now I'm not so convinced that it's not that "gizmo" that I showed. I think I'll change it out as I already have it. The bundle of wiring that is taped and zip-tied on the rear cross-member has grown a lot as it contains the additional wiring for the 7-pin socket plus a heavy wire, circuit breaker and a relay for the cargo trailer running lights. (The trailer has lots of running lights and this modification was needed to keep it from tripping the coach breaker.) I'll let you know how this works out once I get to my place in the country where the coach is stored. 
Rob & Di
2001 U270 34'

Re: Towed Car Lighting Problem

Reply #7 –
I had to replace a convertor as well.  Make sure you get the HD model. 
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Towed Car Lighting Problem

Reply #8 –
I realize our coach is 12 years older than yours, but I had the same problem with the right turn not working. Turns out the wire from the right turn light on the coach to the 7 pin connector was bad. Ran a new wire and now have "juice" to the right turn on the toad.
Subtle hint, and boy do I know! If you do any testing THRU the Gizmo that converts your lights to American standard from International---keep the voltage low!!
18 volt and you will see smoke from the gizmo.
Nitehawk,  Demolition Lady, & our NEW master, Zippy the speeding BB cat.
1989 Grand Villa 36' ORED
Oshkosh chassis, 8.2 DD V8
2006 Saturn Vue AWD

Re: Towed Car Lighting Problem

Reply #9 –
Nitehawk,
I expect if you raised your DC voltage to 18 VDC you would experience more than a little smoke from additional areas. :o

Re: Towed Car Lighting Problem

Reply #10 –
We finally got to work on the coach today. The first thing I did was to hook the Avalanche up to the MH and what do you know, everything works. Go figure. I think I'll just keep an eye on this as it's hard to fix what's not broken.
Rob & Di
2001 U270 34'

Re: Towed Car Lighting Problem

Reply #11 –
Quote from: amos.harrison –
I had to replace a convertor as well.  Make sure you get the HD model. 
Howdy Brett, 
  Do you have the p/n and brand name for the converter?  I may carry one of these as a spare.

Thanks, Dave A
Dave and Nancy Abel
'00 U320 36' WTFE  Build #5669
'10 Jeep Wrangler Unlimited Rubicon
Livingston, TX  SKP's Fulltiming

Re: Towed Car Lighting Problem

Reply #12 –
I went through a series of the $20-25 black plastic converters and continued to have failures. Finally installed a $60 metal Roadmaster Britelite converter and no more problems. Not sure why, but the early failures always affected the toad left turn signal only.
 

Re: Towed Car Lighting Problem

Reply #13 –
Dave,

I don't remember, and can't get to it right now.  I do know that FT Parts was about the same price.

Rob,

I find I regularly have to clean my connector contacts and spread the pins with a knife to keep the connections reliable.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R