reverse light fuse blows

[ackwdw123]

Hi all, I'm trying to track down what appears to possibly be an open circuit. When I put the truck into reverse the back up lamp fuse blows. I replaced the neutral safety switch since I wasn't sure of a way to test if it had anything to do with the reverse lights circuit. Any comments on the images below or suggestions on how to try and approach this electrical issue are greatly appreciated.

01 - The beginning of the rats nest untangling. Any idea what the blue capped wire is for?

02 - The wire connectors for the 328i3 security system.
As soon as the truck is put in reverse the fuse blows, the alarm chimes inside and the brake lights flash. The truck goes into reverse fine and engine runs fine.

03 - These 2 red wires start at a toggle switch mounted under the driver side dash and are now just hanging.

04 - Close up of the blue capped wire.

05 - I'm not sure what these yellow and red wires are.

06 - Not sure what this black Bosch part is other than to be part of the alarm.

 

[The Bronze]

Re: reverse light fuse blows

If it is blowing a fuse, it isn't an open circuit, it is a short circuit.

I never had to deal with reverse wiring being incorporated into the security systems. You can prove me wrong by getting a copy of the manual and finding it in there. Here is the link:

http://www.caralarm.com/manuals-install/Crime Guard/328i3-533i3-745i3.pdf

I would be skipping this step and splitting the system in half and then in half again. Power goes from the fuse up to the ignition switch and over to the reverse switch. It then travels to the main gang plug down by the master cylinder. The rectangular 6 wire connector in there is for the rear light circuits. Removing this and trying a new fuse will seperate wiring outside of the vehicle from the wiring inside the vehicle. If it doesn't blow the fuse, reconnect and disconnect the connector back by the rear bumper (driver's side). If it doesn't blow then, you know which side of the connector the problem lies on.

Then get rid of that alarm system. You will be reconnecting the neutral wiring (Lt Green) for sure.

 

[ackwdw123]

Re: reverse light fuse blows

Thanks for the help and link to the security guide. After taking a look at the guide it doesn't look like the reverse lights are included. Since they aren't working I wanted to rule them out. I'm not having any luck finding the rectangular 6 wire connector near the main gang. I snapped a few pics, could you let me know if I'm in the right place. I appreciate any help with this, all I have to use as documentation is the Haynes manual so if there are any other books or guides on these trucks that show what the connectors are under the hood please let me know.

 

[The Bronze]

Re: reverse light fuse blows

I see it in the second photo. The connector plugs into the block. It is the lower left connector. The harness from it clearly drops down towards the tranny tunnel and travels back to the rear of the truck. Good luck on removing the connector. I have removed these before a few times, and the connectors are a bear to remove. If it is hard, I would try the rear harness first to see if the problem lies there. You can follow the harness visually as well..

 

[ackwdw123]

Re: reverse light fuse blows

Thanks for the help with this, here is what I found and did. I'm back in business now with reverse lights.
The yellow and green light wires were pinched between the frame and a bracket where bare wire was exposed from rubbing. The 4 bolts were removed that were holding a bracket and a pry bar was used to loosen the bracket and free the wires. You could clearly see the 2 wires were pinched behind this bracket. Repair was made with electrical tape and wires were hung with a nylon tie.