New member electrical question

rglaiberman · 01-29-2008, 10:20 AM

I have a 1990 7.3L Diesel with 127,000 miles. My question is why does the 15 amp fuse blow that controls the turn signals, overdrive and backup lights every time I either connect or disconnet my boat trailer. I spliced the ground coming from the truck to the truck body and now when the lights are activated the 15 amp fuse blows. Can somebody help me please? Thanks, Rick

75K30 · 01-29-2008, 10:45 AM

Welcome to the site:
I can only asssume that your trailer has a little bit of a short. Sounds like there is a short in the trailer that is going to ground.
Does this occur only when the trailer is connected?
Are you confident that you actually used the correct wire for ground?

rglaiberman · 01-29-2008, 11:01 AM

Thanks for your reply,

I am positive the short is in the truck and not in the trailer. The trailer has been pulled by my buddy's truck and no problems. Before I bought this Ford I towed the trailer behind a Suburban and no problems.

I beleive the white wire coming out of the bundle is the ground. Should I just take it to my mechanic and have them try to fix it or do you think I can save the money and fix it myself?

Thanks again.

75K30 · 01-29-2008, 11:11 AM

What fun would it be if you took it in to have it fixed? Lol.
Since you have verified that the trailer is alright, you can look into the truck a little further.
First, with the trailer disconnected, does the fuse blow when you turn on the lights, or turn signals? If yes, then we know that the problem is in the truck. If no, then we need to go back to the trailer, and look for anything that may cause this.
I have a trialer that does not like to be towed behind one of my vehicles. I tried to find a problem, and determined that the license plate rubbed through the wiring harness and was going straight to ground. WOuld blow my fuse every time, and would never do this behind another truck. Made me a little crazy for a while.
Anyway, we can run throug a few troubleshooting ideas to see if we can get this problem resolved.
Just need to know if you can duplicate this problem when there is no trailer connected.

75K30 · 01-29-2008, 11:14 AM

See if this helps a little.
Do you have a way to measure voltage, or verify a good circuit?
Here is a diagram.
Trailer Wiring Diagram For 4 way, 6 way and 7 way circuits

rglaiberman · 01-29-2008, 07:28 PM

Appreciate your input. I'll ty to get it taken care of tomorrow

rglaiberman · 01-29-2008, 07:29 PM

Yes. When the trailer is not attached the fuse will blow when the headlights are turned on. Thanks,

75K30 · 01-29-2008, 08:05 PM

Alright, then it is in the harness, and not in the trialer, that is a good thing.
Why did you remove the ground wire? Did you pull it from the plug, and attach it to the truck? I am a little confused about this. You could have a copper strand or something forign in the plug itself and is causing the short. This would do it every time. Maybe we can determine why you felt the need to splice the ground from the truck to the truck body?
The problem is simple, we just have to open the plug to see what the problem is.

crabtruck · 01-30-2008, 12:05 AM

Quote:

Originally Posted by rglaiberman

Yes. When the trailer is not attached the fuse will blow when the headlights are turned on. Thanks,

Welcome to the forum rglaiberman
This seems like a VERY good place to start.
Does the fuse blow with headlights or rather when you get to parking lights?
The distinction helps isolate the problem.
This is what I suspect since you notice this with the trailer.
Should be easy to track down since you know the many symptoms.
Let us know which trailer connector you have, whether it is factory or after.
Does this truck use the same lamp for turn & stop? Does the trailer?
Does this also happen with the key off, when you turn on headlights ?

01-29-2008, 10:20 AM	#1
rglaiberman Junior Member Join Date: Jan 2008 Posts: 4	New member electrical question I have a 1990 7.3L Diesel with 127,000 miles. My question is why does the 15 amp fuse blow that controls the turn signals, overdrive and backup lights every time I either connect or disconnet my boat trailer. I spliced the ground coming from the truck to the truck body and now when the lights are activated the 15 amp fuse blows. Can somebody help me please? Thanks, Rick

01-29-2008, 11:01 AM	#3
rglaiberman Junior Member Join Date: Jan 2008 Posts: 4	new mwmber electrical problem Thanks for your reply, I am positive the short is in the truck and not in the trailer. The trailer has been pulled by my buddy's truck and no problems. Before I bought this Ford I towed the trailer behind a Suburban and no problems. I beleive the white wire coming out of the bundle is the ground. Should I just take it to my mechanic and have them try to fix it or do you think I can save the money and fix it myself? Thanks again.

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01-29-2008, 10:45 AM	#2
75K30 Senior Member Join Date: Jul 2006 Posts: 2,545	Welcome to the site: I can only asssume that your trailer has a little bit of a short. Sounds like there is a short in the trailer that is going to ground. Does this occur only when the trailer is connected? Are you confident that you actually used the correct wire for ground?

01-29-2008, 11:11 AM	#4
75K30 Senior Member Join Date: Jul 2006 Posts: 2,545	What fun would it be if you took it in to have it fixed? Lol. Since you have verified that the trailer is alright, you can look into the truck a little further. First, with the trailer disconnected, does the fuse blow when you turn on the lights, or turn signals? If yes, then we know that the problem is in the truck. If no, then we need to go back to the trailer, and look for anything that may cause this. I have a trialer that does not like to be towed behind one of my vehicles. I tried to find a problem, and determined that the license plate rubbed through the wiring harness and was going straight to ground. WOuld blow my fuse every time, and would never do this behind another truck. Made me a little crazy for a while. Anyway, we can run throug a few troubleshooting ideas to see if we can get this problem resolved. Just need to know if you can duplicate this problem when there is no trailer connected.

01-29-2008, 11:14 AM	#5
75K30 Senior Member Join Date: Jul 2006 Posts: 2,545	See if this helps a little. Do you have a way to measure voltage, or verify a good circuit? Here is a diagram. Trailer Wiring Diagram For 4 way, 6 way and 7 way circuits

01-29-2008, 07:28 PM	#6
rglaiberman Junior Member Join Date: Jan 2008 Posts: 4	Appreciate your input. I'll ty to get it taken care of tomorrow

01-29-2008, 07:29 PM	#7
rglaiberman Junior Member Join Date: Jan 2008 Posts: 4	Yes. When the trailer is not attached the fuse will blow when the headlights are turned on. Thanks,

01-29-2008, 08:05 PM	#8
75K30 Senior Member Join Date: Jul 2006 Posts: 2,545	Alright, then it is in the harness, and not in the trialer, that is a good thing. Why did you remove the ground wire? Did you pull it from the plug, and attach it to the truck? I am a little confused about this. You could have a copper strand or something forign in the plug itself and is causing the short. This would do it every time. Maybe we can determine why you felt the need to splice the ground from the truck to the truck body? The problem is simple, we just have to open the plug to see what the problem is.