Reverse lights stuck on.

[steve1673]

Went to a full-service car wash the other day, and as they drove the car away I noticed the reverse (back-up) lights were stuck on with the car moving forward. 

2018 Edge Sport, 400A

I've done some troubleshooting, but I can't nail down the problem. Here's what I've looked at so far:

 

• reverse lights are always on, regardless of gear position or main light selector. 
• lights turn off when the car is off. 
• other reverse functions (camera, bumper sensors) work properly, only active when gearshift is in reverse.
• Car is 10 months old, has 2 small mods: 
  • HID replacement headlights. Unplugging these make no difference
  • (recent mod) hardwire for radar detector run to wire bundle in drivers side door sill. 
  • I'm guessing that the recent hardwire may have caused the issue, but I can't seem to track it down. The wire was run professionally, soldered to blue/grey wire that is switched 12V
  • I've disconnected this wire completely and no change was seen. I've examined the wire bundle for solder drops, cuts, shorts, etc, but I can't find anything amiss. 

 

So - I'm looking for advice! 

Does the transmission reverse sensor also control the backup cam and bumper sensors? 

does anyone have a wiring diagram specifically showing the wire bundle running along the drivers door sill? (I'm not the best at reading wiring diagrams when there are 50+ wires, so finding something that's specific to that bundle would be helpful. I may end up going to the dealer, but I want to 100% eliminate the possibility that the hardwire caused the problem first. 

any other things I should be looking for?

Thanks! ?

 

 

 

 

[vexer]

This is a huge long shot - but have you looked at the "Backup Light Switch" ? 

As I understand these are typically attached/sitting on top of the transmission, and is what sends the 'signal' to the reverse lights.

 

In an older car I have this caused issues with reverse lights not coming on and I've heard of them short circuiting causing the lights to stay on - though I would assume with a back up camera that means that would also stay on so not 100% convinced that is the issue.

 

I'm not a mechanic, just guessing. 

 

Hope this helps!

[steve1673]

yup - thought of it, but googling around I don't think that the edge uses a traditional reverse switch in the trans. (at least, I can't find any listings on autozone, Ford, or other parts stores). I don't know if there's a switch in the gearshift mechanism, which is another possibility. But like you said, of the three things that are supposed to happen when you put the car in reverse, only one of those is broken, so I'm not sure how everything is connected. 

 

is there a good website that shows parts and wiring diagrams for the edge?

 

 

[candurin]

Is it a standard halogen bulb in the reverse socket?  It almost sounds like there is a single filament bulb when a dual filament one is needed.

 

Are you the original owner and has the bulbs ever been replaced to your knowledge?

 

I cant imagine water got into the housing.

 

I recall the bulb issue with my Jetta many years ago.  It is likely nothing to do with the bulb, but just spitballing.  Try and pick up replacement bulbs from a local auto store and see if that fixes it.

[steve1673]

All original, 1st owner. one gigantic LED assembly for all of the lights on the hatch.

I haven't managed to get the rear hatch disassembled to look at the wiring yet, it's put together pretty well with no visible screws I can undo. 

[enigma-2]

Going on memory from earlier models, on vehicles with automatic transmissions, there is a gear selector switch on the left side. I would assume that this is working as the camera is working properly. 

 

The signal feeds the PCM which triggers the backup light relay in the power fuse panel.

 

As power runs from the relay directly to the reverse lights, I would center in on this relay sticking on.

[wmorastock]

hi guys, i have the same problem, backup camera works fine, but the reverse lights stays on.

 

Could you solve the problem?

[steve1673]

nope. of course the dealer was "unable to replicate" the problem, and they had a month long lead time for appointments.  It wasn't the first electrical issue I had with the car, so I ended up trading it in.