very, very strange electrical problem

[hemi1300]

long story short, have been trying to get the backup cam on my kenwood ddx418/07 dodge ram to activate while shifting into reverse. Can view the cam anytime using the function button (have the cam power tied into accessory power). Strange thing is, ran a wire from head unit reverse wire to reverse wire at tail light, works perfectly switching into camera mode with reverse for about 10 minutes, then all of a sudden the cam will start popping up on screen when i apply the brakes. Did some troubleshooting and discovered the wire is getting 12v while shifting into reverse, 0v in all other gears, but about 2v when i hit the brakes. I think this small 2v spike when applying brakes is making my head unit go ******** and switch to camera mode intermittently. Any ideas, would installing a resistor on the trigger wire at the tail light fix this? Definitely very odd

 

[MegaMouseGW]

Best thing to do is find the wire that goes to the actual reverse switch. Then determine which is live and which is on when the switch is in reverse, and tap into that.

 

[hemi1300]

Ended up getting it fixed finally (fingers crossed). Tried a resistor I had from my hid kit, attached the resistor to the pos reverse wire at my tail light to the reverse trigger wire I had run at the tail light. So far so good, wire now reads 0v in all gears and brakes applied, and 12v in reverse. Backup cam works perfectly now, just hope to hell it stays that way

 

[MegaMouseGW]

Ended up getting it fixed finally (fingers crossed). Tried a resistor I had from my hid kit, attached the resistor to the pos reverse wire at my tail light to the reverse trigger wire I had run at the tail light. So far so good, wire now reads 0v in all gears and brakes applied, and 12v in reverse. Backup cam works perfectly now, just hope to hell it stays that way

Glad you got it fixed with a resistor, but realize that may only be a temporary fix.

 

[hemi1300]

Confused, why would it only be a temporary fix?

 

[MegaMouseGW]

Confused, why would it only be a temporary fix?

I say that because most resistors will go bad after a while, and you may want to be prepared to redo the work at a later date. The resistor may last a month or several years, depending upon the quality of the resistor.

 

[hemi1300]

I say that because most resistors will go bad after a while, and you may want to be prepared to redo the work at a later date. The resistor may last a month or several years, depending upon the quality of the resistor.

not too worried it then, the resistor is a high quality resistor that came from my hid kit from retro solutions. Probably not the appropriate sized resistor for the task, but i had it in the truck as a spare and works flawlessly so far. If my only worry is the resistor failing, no fear, at least i will know what to check and can replace it very easily if need be.

 

[MegaMouseGW]

not too worried it then, the resistor is a high quality resistor that came from my hid kit from retro solutions. Probably not the appropriate sized resistor for the task, but i had it in the truck as a spare and works flawlessly so far. If my only worry is the resistor failing, no fear, at least i will know what to check and can replace it very easily if need be.

Yup Retro has some great quality parts and that should last for a while. Glad that you had a good quality one on hand.

 

[hemi1300]

Thanks for your help, hard to find someone on the forums with electrical experience on vehicles that know what to look for

 

[Ramzaq]

Actually resistor failures are rare normally, the main cause of failure is a high current draw which overheats the resistor and it burns out. Not likely in this situation.

As stated, this is a temporary fix, because you are masking the problem and it may show up from time to time. You should check to make sure that you properly wired the back up camera. Make sure it is attached to the 12v back up wire and only comes on and has voltage when the truck is in reverse and no other time.

The wire is still drawing 2v from something and with the electronics in these new trucks you never know what it could effect and what problems it could cause later.

Just my 2 cents.

 

[hemi1300]

Trust me, I have checked the wiring on the backup camera connections numerous times using my multi meter to check for 12v in reverse only, even re-wired the whole thing in case I had a loose connection somewhere. Made 100% positive I was tapping into the 12v positive wire at the reverse light in the tail light. Very weird that it is getting 2v when brakes are applied, but was tricking my head unit to engage the camera. Cam has worked perfectly since the resistor, and really hope I don't have any future problems. Don't really see how a resistor could do any harm though?

 

[Ramzaq]

Just noticed you are in a 2007, thought it was a 4th gen, my bad.

Electronics are not as touchy in the 3rd gen. But, still you should not be getting cross voltage on the line from your brake lights. Sounds like it might be a high resistance short. When you get some time and things warm up in the east, you may want to check your connectors for Dirt or corrosion. Road salts have been known to do this to connectors. If you clean them with an anti corrosive cleaner make sure you disconnect your battery first.

Double check your grounds in the back and make sure they are good and clean to metal. Look around for any place that the harnesses may have been rubbing and check them carefully.

You will probably be fine the way it is now but I would definitely keep an eye on it.

 

[hemi1300]

Ok, thanks. U had me worried for a second that I might cause big electrical problems. I will definitely keep a close eye on it and try to dig a little deeper into the grounds when I get time

 

[vpalace]

Can anyone tell me what color the pos and neg are for the reverse lights at the taillight?

 

[LS5DodgeRam]

Its funny that you mention this... I have an aftermarket reverse cam with the screen in the mirror... and sometimes it will randomly turn on... I wounder if this is the same problem you are having

 

[LS5DodgeRam]

i hate that i read this thread... lol because now that i am sitting at the light with the brakes applied i now notice the camera flicking on and off -.-

 

[korby05]

Its funny that you mention this... I have an aftermarket reverse cam with the screen in the mirror... and sometimes it will randomly turn on... I wounder if this is the same problem you are having

A little off topic but back up camera do you have?