Reverse light fuse

[Rusty]

Guys, I keep blowing the 20Amp fuse on my 73 Dodge Charger when I go into reverse. This just started after I readjusted my Hurt 4 speed linkage. Has anyone ever heard of the reverse light sensor failing and causing the fuse to blow every time you put it in reverse?

 

[Shorthorse]

Seems like a simple circuit. The normally open switch just passes +12V to the backup lights which are grounded at their sockets. You're obviously introducing a hard ground when the lever activates the switch. One easy test would be to get under the car and manually activate the switch with the car in neutral (I'm not sure if you have to have the ignition switch on or not for your backup lights to work). That should point you in some direction.

 

[Rusty]

I was thinking of trying to bypass the switch tonight to see if I still get the failure, feels like its pulling a high voltage from the ignition circuit. i can drive around all day with the radio on and turn signals working but if I put it in reverse the fuse is gone and you can feel the power surge

 

[Gold Rush]

Basic law of troubleshooting.. If some failure starts immediately after some other action. Go back to that action to begin your search.

I'd disconnect the backup light switch completely and check continuity direct to ground and 12 volt feed. 12 volts should come in and be sent through the switch then to the lights. If you have direct short (zero on lowest meter ohms setting) on the line feeding the lights then you find the short and cure the problem.

 

[Shorthorse]

Basic law of troubleshooting.. If some failure starts immediately after some other action. Go back to that action to begin your search.

I'd disconnect the backup light switch completely and check continuity direct to ground and 12 volt feed. 12 volts should come in and be sent through the switch then to the lights. If you have direct short (zero on lowest meter ohms setting) on the line feeding the lights then you find the short and cure the problem.

Absolutely. Great advice, last thing first.
One word of caution, if you use a volt/ohm meter on any circuit with a bulb, you will see some continuity (ohms) because one side of the a bulbs filament is connected directly to ground. You are looking for a "direct" short so you want to see full deflection on the meter as Gold Rush stated. When in doubt, remove both bulbs.