Reverse lights go when I turn on the parking lights/headlights.
 

An electrical gremlins just hit my truck... My reverse lights are coming on when I pull the knob to turn the lights on. I know little to nothing about electronics so I don't know where to start with sorting this out.

Re: Reverse lights go when I turn on the parking lights/headlights.
 

do they go off when you hit the brakes?

Re: Reverse lights go when I turn on the parking lights/headlights.
 

If you recently changed any bulbs in the rear clusters - check that they are the correct style for the socket (i.e. make sure that there isn't a double contact in a single contact socket & vice-versa). This can cause cross feeding among the lighting circuits.

Unfortunately, if that isn't the problem, you are probably looking at a short between the lead to the parking lights and the lead for the back-up lights. Crawl under and inspect the wiring harness from the firewall back to the rear clusters. Any damage to the harness sheathing, that is bad enough to cause a short, should be easy to spot. Pay especially close attention to areas where it passes close to the exhaust system.

The cab wiring for the back-up lights is seperate and distant from the wiring for the other lights. It does not come near those other circuits until they all join together at the firewall (on the cab side). After that, the leads for the back-up, parking & brake lights are all bundled together in that plastic sheathing.


http://s3d3.turboimagehost.com/t1/17572417_2.jpg http://s3d3.turboimagehost.com/t1/17572418_4.jpg http://s3d3.turboimagehost.com/t1/17572419_5.jpg http://s3d3.turboimagehost.com/t1/17572420_6.jpg http://s3d3.turboimagehost.com/t1/17572421_7.jpg http://s3d3.turboimagehost.com/t1/17572422_9.jpg http://s3d3.turboimagehost.com/t1/17572423_10.jpg

Re: Reverse lights go when I turn on the parking lights/headlights.
 

Backup lights are very separate from the other circuits. If it was turn and parking lights at the same time I'd say look at the bulbs but...
Likely it's in the back and that's really quite simple. There are only 4 circuits with a common ground behind the LH tailight lens. Has U-Haul or some tool rental joint hacked up the taillight wiring for a trailer plug?

Re: Reverse lights go when I turn on the parking lights/headlights.
 

Yeah there was a trailer brake installed but I removed it a couple weeks ago when I swapped the painted bumper for a chrome one. The reverse lights didn't start to come on with the other lights until last night though. I've removed the reverse light bulbs for now and I'll check out everything you guys have said when I get home from work tonight.

Re: Reverse lights go when I turn on the parking lights/headlights.
 

I replaced the reverse light bulbs, now it's back to normal... I guess 39-year-old light bulbs don't work as they should sometimes haha