Hello forum folks,
Due to mis wiring of my trailer, I now have a short circuit in my car: XC90 2004
The fuse 33 of the front and rear parking lights on the right and number plate lights breaks as soon as the cars is started.

I do not know where to start searching to find the problem.

Any suggestions?

Kind Regards,
Wouter

 

Fuse blows with the trailer wiring hooked up or with it unplugged.

 

Unplugged.
I already checked the with the electric wiring of the towing part disconnected.

 

I think that the positive of the parking lights was used as ground when the trailer was connected.
Now there is a short circuit in the car's parking lights on the right.

 

Does someone have an electric wiring schematic?
Then I can see where the wires start en end and I do not have to follow the entire cable boom behind the panels of the interior.

 

have you disconnected the trailer wiring harness to return the car to "stock"? I'd pull that out (disconnect/remove, not just unplug) to make sure that you don't have a bad harness/connector or the miswiring melted some insulation causing a new short. If you have the harness off, then you can probe voltage points to make sure they are not grounded - ie fuse out, measure voltage to insure the circuit is isolated then measure impedance to make sure its not grounded.

To find a wiring diagram, I'd start by looking on https://www.matthewsvolvosite.com/ or google "Volvo XC90 wiring diagram" (plenty of paid sites) to see if you can find something on a blog or forum.

Also check out etrailer.com as they sell wiring kits and have good vehicle specific content on the install.

 

Thank for the message.
So, the entire socket for the trailer connection is disconnected. there is no power on that part. The fuse for the parking lights is broken and I pulled it out of the fuse box.
There is 12v across the pins for the fuse.
There is 0.16V over the light pins.
How do I now use my multi meter for step by step searching for the problem? Where do I put the + and where the - of the meter?
Does someone have a schematic drawing of the principle how to find the problem?

 

The principle of finding the problem is to see where you are supposed to have +12V doesn't have zero or low resistance to ground. You need to see what's on the circuit as devices like light bulbs will appear like resistors and you want to isolate each circuit segment as best you can. The more you can unplug the better, then you can add them back in until something changes... or if you are lucky you will find a specific wire path that should be isolated appears to be grounded. That's wehre the wiring diagrams come into play. As my son likes to say "its tedious but not difficult" .

 

Dear mt6127, Thanks. I'll go with the un-plugging piece by piece in the parking light circuit.
I hope that I can report progress shortly.
If not, I'll just drive by the garage.

 

Solved!
After puzzling with my meter I found that the back side right parking light measures exactly like the left one. I even got the panels out to access the shunt (what ever it does, I don't know). The shunts were all measuring the same. So, my conclusion was that the problem should be in the front.
First thing I did was checking the light bulb of the parking light right front. Guess what, the pin was bent and contacted the wrong connector pole.
(I do not know if my English is good enough)
So, I learned: check the lights first when there is a short circuit in the light circuit.

Thanks for you help!