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No trailer light voltage

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Old Aug 19, 2001 | 12:58 PM
  #1  
jfbertrand's Avatar
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No trailer light voltage

I have a 98 F150 and never cared that much about a trailer before. I had to tow something yesterday and discovere that I have no power from the bumper connectors, DAMN!

The plug is there and seems to be connected of the main light plug, under the frame. I even unplugged the conenector in question and found that there is not even power out to that connector. Is there a switch somewhere that I have to turn on??

Thanks.

JF
 
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Old Aug 19, 2001 | 01:02 PM
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No trailer light voltage

JF, this sounds like a dirty/broken connection somewhere in the wiring. get a test light and maybe a voltmeter to check this out. Have some electrical tape and connectors handy before you start on this. Best of luck on this.

Wayne 60 F-350
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Old Aug 19, 2001 | 06:26 PM
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No trailer light voltage

The trailer IS fine, and the main connector (the one that provides the current to the back end of the truck) works. The trailer harness, 3 smaller size (probably 20, inside the main connector and 18 outside the connector) connectors are dedicated to the trailer (at least this is what I got from following the cables to the connector. If it helps, the connector I'm talking about is located on the frame close to the spare on the drivers side of the truck.

I have look at the cables and they are fine (at least from what I can tell). When I take my voltmeter and open the connector up, I measure voltage and I have nothing where the trailer harness is connected. I get plenty of voltage ~12V on the others but nothing on the ones the trailer is connected to.

I was told that sometimes, the dealers will not implement all the circuitry on purpose so that you have to go to them to get the trailer light to work.

Anyway, if I'm not clear, I can take pictures and post them here.


Later

JF
 
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Old Aug 19, 2001 | 08:46 PM
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whomrig
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No trailer light voltage

JF, go ahead and post yer pics and we'll see if I can help you.

Wayne 60 F-350
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http://home.pacbell.net/whomrig

 
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Old Aug 20, 2001 | 06:59 AM
  #5  
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No trailer light voltage

I'm not sure about the '96, but the newer ('97 & up) trucks with the factory towing package have a sperate set of fuses and relays for the trailer connector. The idea being that if you have a short in your trailer lights it will not affect your truck lights. It may be possible that the fuses have been used as "spares" at some time previously or that some short may have occurred that resulted in the fuses being "blown". I have a friend that bought a 2001 F-350 dually and immediately blew the trailer towing fuses because he thought it was "smart" to have his own trailer wiring system. He used to wire his trailers so that activation of the normal running lights would apply the trailer brakes! Somehow this was a theft deterrent or would slow them down. Anyhow, all this did was blow the fuse on his new truck as brakes draw much more current than the running light circuit was fused for. Point is, there are some weird things that go on in the trailer light world. I have been amazed at how many folks don't realize there is a "standard" that has been adopted regarding the different trailer connectors.
 
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Old Aug 20, 2001 | 09:41 AM
  #6  
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No trailer light voltage

Actually, that's what I'm looking for. A switch or inline fuse that would enable the trailer lights. It has never worked (or been turned on). My father in law is a RV guy and he tells me that he has heard stories of people buying brand new truck and hooking up the trailer just to see that there is no power comming out of the trailer hitch! He also told me that there is always a switch or connector that needs to be turned on, because it's not on by default.

I just have the 4 connector harness. Some people told me I should have 7 but I'm not too worried about that because I didn't get the towing package and the trailer only needs 4 as well.

Thanks for all of your time.

JF

 
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Old Aug 25, 2001 | 05:39 PM
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No trailer light voltage

I had the same problem!
Turn on the engine, keep it running and you'll have juice in the back.
Without the key on, there's no juice flowing back to the connector.

 
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Old Aug 26, 2001 | 09:12 AM
  #8  
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No trailer light voltage

[font size="1" color="#FF0000"]LAST EDITED ON 26-Aug-01 AT 10:13 AM (EST)[/font][p]Turns out, I had fuses problem!

It's not really a big deal if they would have been DOCUMENTED.

I learned (after 4 days or search) that there are 4 fuse panel not 2. In the owner manual, they talk only about the main fuse panel under the hood and the one under the dash. There is another one that is located just next to the main fuse panel under the hood, and it's taped with electrical tape. It contains 6 fuses in line (only two slots were populated on mine).

I found that fuse 1 (20 amp) of the main fuse panel is the marker ligths on the trailer and that fuse 2 of this misterious panel is the power to the flashers for the back.


Well like they say, you live you learn.


JF
 
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No trailer light voltage

 
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