7 Way Problem

[Jim & Susan]

Greetings. I normally tow with a 1998 F150. All the lights, brakes, etc work normally when the 'Stream is pluged into that truck. Recently, I had the opportunity to borrow a buddy's F350 to tow thru the mountains. Great truck. Tows the Overlander like it's not even there. Problem I'm having is that the left rear Brake/Turn signal won't work on the f350. I've done all the normal trouble-shooting. proper volatge is avalable on the 7 way at the truck. It's also there on the umbilical, just doesn't want to work when I plug it in to the 'Stream.

What gives?

Jim

[TG Twinkie]

Sounds like the 2 trucks are wired differently. While your truck matches the trailer, the F350 does not. Did you check which terminal on the trailer is used on the turn/brake circuit and make sure it matches the same terminal on the F350?
Does the turn signal/brake light work on the F350 when the trailer is plugged in?

[ROBERTSUNRUS]

Hi, I know this sounds too simple, but did you check the light bulb?

[Jim & Susan]

Yep, bulb works and the two trucks have the same 7-way. Everything else works exactly the same on both truck 7-way connectors except that one pin (for the left brake/turn). Crazy thing is that normal voltage is there when I test with the multi-meter. In other words, everything tests normal, it just doesn't want to work on the camper.

Jim

[Aage]

Originally Posted by Jim & Susan

Crazy thing is that normal voltage is there when I test with the multi-meter.

Here's a crazy idea: reverse the umbilical cord (switch around the ends). I was told to do this once, and I found it cured my problem.

[Lumatic]

Airstream had a different confirguration in 73 from what now is an industry standard. If all the lights worked with your F150 changes were made so the truck is compatable with the trailer. I suspect the wiring on the F350 is wired to a different configuration. What year is the 350?

[Aage]

Originally Posted by Lumatic

Airstream had a different confirguration in 73 from what now is an industry standard. If all the lights worked with your F150 changes were made so the truck is compatable with the trailer. I suspect the wiring on the F350 is wired to a different configuration. What year is the 350?

I think that is why the umbilical only works one way in my TT: one end (the TV end) was re-wired in the new system, but the other end was left as it was originally wired back in the day.

So, I marked the TV end on mine and forgot about the problem.

Heck doesn't cost anything to try it...

[Jim & Susan]

The F350 is a 2000. The F150 is a 1998. They both use the same connector on the TV. Pinout is exatly the same on both trucks. The umbilical connectors are not the same on the truck and camper, so I can't simply reverse them.

[Lumatic]

Get a test light and diagram which blades do what. If you compare the 150 with the 350 my bet is they are slightly different. You can also take a jumper and connect each terminal on the umbilical and see which one is for the left brake/turn and see if it corresponds to the plug on your tow vehicle.

It could also be a bad tow package relay in your truck. The brake and signal light could work on your TV but if the relay is bad the signal won't get to the trailer.

[Aage]

Originally Posted by Jim & Susan

The F350 is a 2000. The F150 is a 1998. They both use the same connector on the TV. Pinout is exatly the same on both trucks. The umbilical connectors are not the same on the truck and camper, so I can't simply reverse them.

OK, I get it now. On my outfit, the cord can go either way; same connectors on the TV and TT.

[Jim & Susan]

Originally Posted by Lumatic

.......It could also be a bad tow package relay in your truck. The brake and signal light could work on your TV but if the relay is bad the signal won't get to the trailer.

I'm begining to think this may be the issue. The Pin-outs are exactly the same on both trucks. The only odd thing that I noticed after extensively testing with a multi-meter is that the voltage coming off the truck is only 11.7 volts. The weird thing is that all the other lights function normally at that voltage. Only the left turn/brake light won't work on the camper.

Since the F350 is not my truck, I'll just have to put up with it for the trip home tomorrow. The good news is that I haven't let the smoke out of any of the wires yet. Wish me luck...........

Jim

[ROBERT CROSS]

Jim,
I'm sending the grey cells back a few years so bear with me...

I had a similar bulb/circuit problem with our 95 Burb. Solved by installing matching new bulbs in brake/turn in TV and installing new h/d flasher.

Bob

[Jim & Susan]

Originally Posted by ROBERT CROSS

Jim,
I'm sending the grey cells back a few years so bear with me...

I had a similar bulb/circuit problem with our 95 Burb. Solved by installing matching new bulbs in brake/turn in TV and installing new h/d flasher.

Bob

Just to kinda close the thought here, so to speak.....

I'm thinking this or Lumatic's idea back in post number 9 must have some bearing on the problem. I got the Airstream home on Monday without any problems. Just took it easy and made sure to merge to the left when nobody was around. This trip was almost all Interstate travel, so I could "pick my spot" to change lanes most of the time.

Once home, I took voltage readings on my truck and sure enough it came in at 12.1v (versus 11.7 on the loaner truck). That tiny amount was causing issues for whatever reason. At any rate my truck is working fine, so we'll be ready for springtime travel. Savannah in April, here we come! I really didn't want to have to repair my already restored tail lights .

One more thing. For those of you sitting on the fence trying to decide between a 1/2 ton tow vehicle and a heavy duty (3/4 ton or above)......my next one will be a 3/4 on. A world of difference between my 1/2 ton and that F350.

Thanks for the tips, boys. After eight years on this forum, it's still the best place on the 'net for 'Streamin' information.

SYDTR,

Jim